Micro LED display panel, manufacturing method thereof, and display device

Abstract

This application discloses a micro LED display panel, a manufacturing method thereof, and a display device. The present application provides a micro LED display panel having multiple display structures. Each display structure includes a first electrode, a second electrode, a first semiconductor layer, a second semiconductor layer, and a light-emitting layer. The first electrode, the first semiconductor layer, and the light-emitting layer of adjacent display structures are independent of each other. The first semiconductor layer and the second semiconductor layer are respectively disposed on two sides of the light-emitting layer. The first electrode is disposed on the side of the first semiconductor layer away from the light-emitting layer, and the second electrode is disposed on the side of the second semiconductor layer away from the light-emitting layer. The light-emitting layer of each display structure corresponds to one pixel area. The second electrode is routed around each pixel area, and the second electrode is a common electrode for each pixel area and a metal barrier wall between adjacent pixel areas. This solution can increase the area of ​​the light-emitting area and improve light efficiency. Furthermore, mass transfer is not required, improving the qualification rate. The second electrode acts as a metal barrier wall to prevent optical crosstalk, promoting even distribution of current and improving brightness uniformity.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] The present invention provides Claiming priority from PCT / CN2023 / 103087 filed on June 28, 2023, Priority is claimed to Chinese Patent Application No. 202211079222.8, entitled "MICRO-LED DISPLAY PANEL AND MANUFACTURING METHOD THEREFOR, AND DISPLAY DEVICE," filed with the State Intellectual Property Office of China on September 5, 2022, which is incorporated herein by reference in its entirety.

[0002] [Technical field] The present invention relates to the technical field of display screens, and in particular to a micro LED display panel and its manufacturing method, and a display device. [Background technology]

[0003] Currently, as display technology continues to develop, micro light-emitting diodes (microLEDs) have become a new generation of popular display technology. MicroLEDs have advantages such as ultra-high resolution, color saturation, flexible display, and long life, and can also be used as pixelated array light sources in fields such as photosensitivity, projection, and optical communication. Currently, microLEDs with tens of thousands of pixels can be used in fields such as smart headlights, augmented reality (AR), and virtual reality (VR). MicroLEDs need to develop toward miniaturization, high brightness, and integration.

[0004] Currently, micro LED chips with flip-chip structure are mainly used in the industry. Mini LED with flip-chip structure Tips The process is mature, so as long as the size of the mini LED chip is slightly reduced, micro LED TipsThe micro LED chiplets are then transferred to a substrate via mass transfer, and finally, bonding is performed to connect the circuits. To enable each display unit to emit light independently, a barrier wall needs to be fabricated on the substrate to prevent optical crosstalk between the display units.

[0005] However, flip-chip structured micro LED chips have a small light-emitting area because part of the light-emitting area needs to be etched to expose the electrodes. To transfer the micro LED chips from the wafer to the substrate, mass transfer and bonding technology is used, which imposes very high requirements on the chip qualification rate, transfer qualification rate, bonding qualification rate, etc. As a result, the total qualification rate cannot be effectively ensured, and the cost is high and engineering is difficult to implement. In addition, the barrier wall teeth However, the substrate has an irregular shape and a non-uniform size, so the barrier wall is difficult to match with the device. In addition, the μm-level lithography process on the package side is not yet mature, which causes the risk of the barrier wall collapsing and optical crosstalk. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, the present invention provides a micro LED display panel and its manufacturing method, and a display device to ensure a product qualification rate, and the barrier wall does not need to be specially manufactured, thereby reducing the process flow.

[0007] The present invention provides a micro LED display panel including a plurality of display structures. Each display structure includes a first electrode, a second electrode, a first semiconductor layer, a second semiconductor layer, and a light-emitting layer. The first electrode, the first semiconductor layer, and the light-emitting layer of adjacent display structures are independent of each other. The first semiconductor layer and the second semiconductor layer are respectively disposed on two sides of the light-emitting layer. The first electrode is disposed on the side of the first semiconductor layer away from the light-emitting layer, and the second electrode is disposed on the side of the second semiconductor layer away from the light-emitting layer. The first electrode and the second electrode of the display panel are not disposed horizontally but vertically. The first electrode and the second electrode are located on the upper and lower surfaces of the second semiconductor layer, respectively. In this way, part of the light-emitting region does not need to be etched to expose the second electrode. The light-emitting layer of each display structure corresponds to one pixel region. The second electrode is routed around each pixel region. Even when the light-emitting regions are arranged in an array, the second electrode is a common electrode for each pixel region, and is configured to serve as a metal barrier wall between adjacent pixel regions, preventing optical crosstalk and eliminating the need for a separate barrier wall. The process is simple and easy to implement in engineering. It also promotes uniform current distribution and improves light uniformity. Furthermore, the vertical structure in semiconductor processing eliminates the need for mass transfer, ensuring product certification rates.

[0008] The application scenario of the display panel is not particularly limited in this application. The display panel uses micro LEDs for display. The display panel can be used in the display screen of a device, for example, the display screen of an electronic device such as a mobile phone, or the display screen of a wearable device such as a watch. In addition, the application scenario can also be a scenario with high current and high pixel density, such as a smart vehicle light, an AR device, or a VR device. Micro LEDs can also be used as a pixelated array light source in fields such as photosensitivity, projection, and optical communication.

[0009] In a possible embodiment, the side of the second electrode is inclined, and the inclination angle ranges from 30 degrees to 150 degrees. The side of the second electrode is designed with an inclination, which helps to collect light and improve light efficiency.

[0010] In a possible embodiment, the side walls of the display structure are inclined, with an angle of inclination ranging from 30 to 150 degrees. The side walls of the display structure are inclined, with an angle of inclination ranging from 30 to 150 degrees. Inclination angle is the second electrode Aspects of When the tilt angle of the sidewalls matches the tilt angle of the sidewalls, light can be collected and the slope of the sidewalls helps to drain current and prevent current congestion.

[0011] In a possible embodiment, the second electrode in contact with the second semiconductor layer is partially or completely embedded in the second semiconductor layer to further separate light between adjacent display structures.

[0012] In a possible embodiment, a passivation layer is deposited on the second semiconductor layer, the light emitting layer, and the etched edge of the first semiconductor layer, and the side of the second electrode that is buried in the second semiconductor layer is in contact with the passivation layer.

[0013] In a possible embodiment, the display panel further includes a transparent conductive layer disposed between the second semiconductor layer and the second electrode. The transparent conductive layer functions as a transition between the second electrode and the second semiconductor layer, solving the problem of ohmic contact between metal and semiconductor and reducing resistance. In addition, the transparent conductive layer is distributed over the entire surface, helping to spread current more evenly and improving light efficiency, thereby avoiding the problem of uneven brightness and improving the reliability of the display panel. In addition, the transparent conductive layer, when combined with a pixelated and routed second electrode, can reduce power, voltage, and power consumption.

[0014] In a possible embodiment, the side of the second electrode that contacts the transparent conductive layer is at least partially embedded in the transparent conductive layer. Alternatively, the side of the second electrode that contacts the transparent conductive layer is at least partially embedded in the transparent conductive layer and the second semiconductor layer. To improve the light-shielding effect of the second electrode, the second electrode may be embedded in the transparent conductive layer, or may be embedded in the transparent conductive layer and the second semiconductor layer. The material of the transparent conductive layer is not particularly limited in this application. For example, indium tin oxide, indium zinc oxide, etc. may be selected as the transparent conductive layer.

[0015] In a possible embodiment, the surface of the second semiconductor facing away from the light emitting layer exhibits a crystalline structure, for example, a sawtooth, wave, etc., in order to improve light emitting efficiency and reduce light reflection.

[0016] In a possible embodiment, the first electrode is a surface electrode, and the first electrode covers the surface and sidewall of the first semiconductor. The first electrode is a surface electrode that has both the functions of electric field and light reflection, so that the emission angle can be effectively reduced, light collection can be performed, and the front brightness of the chip can be improved, and light efficiency can be improved.

[0017] The display panel further comprises a plurality of switches. Each display structure corresponds to one switch, and the first electrode is configured to connect to the corresponding switch. The state of the switch determines whether the light-emitting layer emits light. situation The switches are controlled by a driver circuit, which can receive control signals from the device's controller. CMOS is preferably used as the switch, for example silicon Si-CMOS. Silicon has good heat resistance, making it particularly suitable for use in vehicle lighting scenarios.

[0018] In a possible embodiment, the second semiconductor layers of the display structures are connected, communicated, or communicated, and the thickness of the second semiconductor layer at the junction of adjacent display structures may be greater than a coarsening depth to prevent chip destruction.

[0019] In a possible embodiment, the second semiconductor layers of the display structure are connected, communicated, or communicated with each other. The first semiconductor layer and the second semiconductor layer are carrier transport layers. The charge polarity of the first semiconductor layer is the same as the polarity of the first electrode, and the edge charges repel each other, so that the sidewall effect can be effectively reduced. The charge polarity of the second semiconductor layer is the same as the polarity of the second electrode. The second semiconductor layer The charge polarity of The polarity of the first electrode anti They are paired, and the edge charges absorb each other, making it easier for current to spread and improving efficiency.

[0020] In a possible embodiment, the first electrode comprises an ohmic electrode and a reflective electrode, the ohmic electrode configured to connect to the first semiconductor layer, the reflective electrode connected to a driving circuit, and the reflective electrode further configured to reflect light.

[0021] The surface and sidewalls of the first semiconductor layer may be provided with a reflective layer and may be enveloped in the reflective layer, which may be a thin film material with high reflectivity, such as a metal reflector or a metal and distributed Bragg reflector composite layer.

[0022] In a possible embodiment, the shape of the second electrode is either triangular, rectangular, circular or polygonal.

[0023] The present invention further provides a display device including the above-mentioned micro LED display panel, and further including a driving circuit and a controller. Each display structure is connected to a corresponding switch. The controller is configured to control the driving circuit to drive the switch. When the switch is turned on, the light-emitting layer emits light.

[0024] In a possible embodiment, the switch is a complementary metal oxide semiconductor (CMOS) switch or a thin film transistor TFT switch.

[0025] Based on the above-mentioned micro LED display panel, the present invention further provides a manufacturing method for a micro LED display panel. The advantages of the above-mentioned display panel solution are also applicable to the following method, the details of which will not be described again below. The manufacturing method includes the steps of: obtaining a first semiconductor layer, a light-emitting layer, and a second semiconductor layer stacked in sequence; etching the first semiconductor layer, the light-emitting layer, and the second semiconductor layer to form a penetrated first semiconductor layer and light-emitting layer and a partially penetrated second semiconductor layer; forming a first electrode on the side of the first semiconductor layer away from the light-emitting layer; and forming a second electrode on the side of the second semiconductor layer away from the light-emitting layer, wherein the second electrode is routed around each pixel region, the second electrode is a common electrode for each pixel region, and the second electrode serves as a metal barrier wall between adjacent pixel regions. The display panel manufactured using the method of the present invention does not require mass transfer and can be directly integrated with a switch and then directly packaged, reducing the process flow and facilitating commercialization.

[0026] In a possible embodiment, the step of forming the first electrode includes: opening a hole on the side of the first semiconductor layer away from the light emitting layer for depositing an ohmic electrode; and performing evaporation on a reflective electrode, wherein the first electrode comprises an ohmic electrode and a reflective electrode.

[0027] In a possible embodiment, before the step of forming the first electrode, the method further comprises the step of depositing a passivation layer, which has stable chemical properties and can therefore achieve a protective function.

[0028] In a possible embodiment, the step of forming a second electrode on the side of the second semiconductor layer away from the light-emitting layer specifically includes the steps of bonding the display panel to the first substrate via a bonding layer to expose the second semiconductor layer, and forming the second electrode on the second semiconductor layer by routing around each pixel area.

[0029] In a possible embodiment, after the step of forming the second electrode, the method further includes the steps of performing bonding and transferring the display panel to a second substrate, removing the first substrate to expose the first electrode, and connecting the first electrode to a corresponding switch.

[0030] The present invention has at least the following effects.

[0031] The micro LED display panel provided in the present invention uses a vertically structured chip architecture and includes multiple display structures distributed in an array. Each display structure includes a first electrode, a second electrode, a light-emitting layer, a first semiconductor layer, and a second semiconductor layer. The first and second semiconductor layers are respectively disposed on two surfaces of the light-emitting layer. The first electrode is disposed on the side of the first semiconductor layer away from the light-emitting layer, and the second electrode is disposed on the side of the second semiconductor layer away from the light-emitting layer. The first and second electrodes are disposed on the top and bottom surfaces of the chip, respectively. In this way, there is no need to etch the light-emitting region to expose the second electrode, and the area of ​​the light-emitting region is not wasted, thereby increasing the area of ​​the light-emitting region and facilitating improved light efficiency. Furthermore, since mass transfer is not required in the semiconductor process due to the vertical structure, product certification rates can be ensured. In addition, the second electrode in this embodiment of the present invention is a common electrode and is routed around the periphery of the pixel region. Specifically, the second electrode can function as a metal barrier wall between pixel regions to prevent optical crosstalk between pixel regions and facilitate pixelated routing of the second electrode. This can make current distribution more uniform, and furthermore, the brightness of the display panel more uniform. No special steps are required in the process of manufacturing the barrier wall, which reduces the process flow and facilitates productization. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram showing a micro LED chip with a flip-chip structure. [Figure 2] FIG. 2 is a cross-sectional view of a micro LED display panel according to one embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating a plan view corresponding to FIG. 2, according to one embodiment of the present invention. [Figure 4a] FIG. 4a is a diagram illustrating another cross section of a micro LED display panel according to one embodiment of the present invention. [Figure 4b]FIG. 4b illustrates yet another cross-section of a micro LED display panel according to one embodiment of the present invention. [Figure 5] FIG. 5 illustrates yet another cross-section of a micro LED display panel according to one embodiment of the present invention. [Figure 6] FIG. 6 illustrates yet another cross-section of a micro LED display panel according to an embodiment of the present invention. [Figure 7] FIG. 7 illustrates a further cross section of a micro LED display panel according to one embodiment of the present invention. [Figure 8] FIG. 8 is a diagram illustrating the structure of the first step of the manufacturing process of a micro LED display panel according to one embodiment of the present invention. [Figure 9] FIG. 9 is a diagram illustrating the structure of a second step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention. [Figure 10] FIG. 10 is a diagram illustrating the structure of a third step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention. [Figure 11] FIG. 11 is a diagram illustrating the structure of a fourth step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention. [Figure 12] FIG. 12 is a diagram illustrating a display device according to an embodiment of the present invention. [Figure 13] FIG. 13 illustrates a flowchart of a manufacturing method for a micro LED display panel according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The following describes the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application.

[0034] In the following description, terms such as "first" and "second" are intended for descriptive purposes only and should not be construed as an indication or implication of relative importance or quantity of the technical features shown. Thus, features qualified by "first," "second," etc. may explicitly or implicitly include one or more features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0035] It should be noted that in the present invention, the term "connection" should be understood in a broad sense unless otherwise expressly specified and limited. For example, "connection" may be a fixed connection, a detachable connection, or an integrated connection, and may be a direct connection or an indirect connection via an intermediate medium. In addition, the term "coupling" may refer to a manner of implementing an electrical connection for signal transmission. "Connection" may be a direct electrical connection or an indirect electrical connection via an intermediate medium.

[0036] In order to allow those skilled in the art to better understand the technical solutions provided in the embodiments of the present invention, the following first describes application scenarios of the technical solutions.

[0037] The application scenario of the display panel is not particularly limited in the embodiments of the present invention. The display panel uses micro LEDs for display. The display panel can be used in the display screen of a device, for example, the display screen of an electronic device such as a mobile phone, or the display screen of a wearable device such as a watch. In addition, the application scenario can also be a scenario with high current and high pixel density, such as a smart vehicle light, an AR device, or a VR device. Micro LEDs can also be used as a pixelated array light source in fields such as photosensitivity, projection, and optical communication.

[0038] Conventional micro LED chips use a flip-chip structure with a mature process. Figure 1 shows a diagram of a micro LED chip with a flip-chip structure.

[0039] As can be seen from FIG. 1, the two electrodes of the micro LED chip with a flip-chip structure, namely the first electrode 30 and the second electrode 50, are distributed on the same side of the second semiconductor layer 10. In addition, the second electrode 50 can only be removed after etching a part of the light-emitting region 20. As a result, the light-emitting region Area of is always smaller than the size of a single display unit, and has low efficiency in application scenarios with large current and high pixel density. The increase in pixel density requires continuous reduction in chip size, and the efficiency of the flip-chip structure cannot be kept in sync.

[0040] Therefore, the light-emitting area Area of To increase the display area, the flip-chip structure cannot meet the demand, and a barrier wall 60 must be placed between adjacent display units to prevent optical crosstalk. The barrier wall process is also difficult to implement from an engineering standpoint.

[0041] In the present invention, the light-emitting region of the micro LED chip having a flip-chip structure is Area ofTo solve the technical problem of the small size of the micro LED display panel, making it difficult to engineer a barrier wall, a vertically structured micro LED display panel is used. The first and second electrodes of the display panel are not arranged horizontally but vertically. The first and second electrodes are located on the upper and lower surfaces of the second semiconductor layer, respectively. This eliminates the need to etch a portion of the light-emitting area to expose the second electrode. In addition, the display panel provided in this embodiment of the present invention implements pixelated routing for the second electrode within the array display units of the entire display panel. That is, the second electrode is a common electrode for the display units, and the second electrode can function as a barrier wall. This can block optical crosstalk between the display units, eliminating the need for a separate barrier wall. The process is simple and easy to implement.

[0042] In order to enable those skilled in the art to better understand the display panel provided in the embodiments of the present invention, the following provides a detailed description with reference to the accompanying drawings.

[0043] FIG. 2 is a cross-sectional view of a micro LED display panel according to one embodiment of the present invention.

[0044] The micro LED display panel provided in this embodiment of the present invention includes a plurality of display structures 100. As shown in the dashed box in Fig. 2, each display structure 100 includes a first electrode 25, a second electrode 21, a first semiconductor layer 24, a second semiconductor layer 22, and a light emitting layer 23. The first electrodes 25, first semiconductor layers 24, and light emitting layers 23 of adjacent display structures 100 are independent of each other. That is, each display structure 100 has a one-to-one correspondence with the first electrodes 25, first semiconductor layers 24, and light emitting layers 23.

[0045] In this embodiment of the present invention, there is no particular limitation as to whether each display structure 100 has a one-to-one correspondence with the second semiconductor layer 22. Specifically, the second semiconductor layers 22 of the display structures 100 may be independent of each other, or the second semiconductor layers 22 corresponding to all the display structures 100 may be connected. In this embodiment, an example in which the second semiconductor layers 22 of all the display structures 100 are connected will be described.

[0046] The first semiconductor layer 24 and the second semiconductor layer 22 are respectively disposed on the surfaces on two sides of the light emitting layer 23. The first electrode 25 is disposed on the side of the first semiconductor layer 24 that is remote from the light emitting layer 23, and the second electrode 21 is disposed on the side of the second semiconductor layer 22 that is remote from the light emitting layer 23.

[0047] The first electrode 25 is configured to connect to a switch corresponding to the display structure 100. As shown in the figure, a metal solder joint 26 is further disposed between the first electrode 25 and the switch. It should be understood that each display structure 100 corresponds to one switch, and the state of the switch determines whether the light-emitting layer emits light. For example, when the switch is turned on, the light-emitting layer emits light, and when the switch is turned off, the light-emitting layer does not emit light. The switch is controlled by a drive circuit. The drive circuit receives a control signal from a controller of the device and can further generate a drive signal based on the control signal to drive the state of the switch.

[0048] The first electrode 25 is a surface electrode, and covers the surface and sidewalls of the first semiconductor layer 24. For example, the first electrode 25 completely covers the surface and all sidewalls of the first semiconductor. The first electrode is a surface electrode that has the functions of both electric field and light reflection, which can effectively reduce the emission angle, achieve light collection, improve the forward brightness of the chip, and improve light efficiency.

[0049] Both the first semiconductor layer 24 and the second semiconductor layer 22 are carrier transport layers. The charge polarity of the first semiconductor layer 24 is the same as that of the first electrode 25, and the edge charges repel each other, effectively reducing the sidewall effect. The charge polarity of the second semiconductor layer is the same as that of the second electrode. The second semiconductor layer 22 is charged and electrically opposite to that of the first electrode 25, and the edge charges absorb each other, facilitating current spreading and improving efficiency.

[0050] The surface and sidewalls of the first semiconductor layer 24 may be provided with a reflective layer, which may be wrapped in a reflective layer. The reflective layer may be a thin film material with high reflectivity, such as a metal reflector or a metal and distributed Bragg reflection (DBR) composite layer.

[0051] The type of switch is not particularly limited in the present invention. For example, the switch may be a complementary metal-oxide-semiconductor (CMOS) switch or a thin-film transistor (TFT) switch, or another type of switch transistor. CMOS has many advantages over TFT. Therefore, CMOS is preferably used as the switch, such as silicon Si-CMOS. Silicon has good heat resistance and is particularly suitable for applications in vehicle lighting scenarios. In addition, CMOS and display structures can be integrated on a chip, enabling wafer-level integration without the need for mass transfer. In scenarios requiring high current, such as vehicle lights, the current of TFTs cannot meet the requirements, and the current of a single chip is too small. CMOS is suitable for applications in high-current, high-density scenarios and can meet the current and thermal resistance requirements.

[0052] Each display structure further includes an adhesive layer 27 and a passivation layer 29 .

[0053] The light-emitting layer 23 of each display structure corresponds to one pixel region.

[0054] The second electrode 21 is routed around the periphery of each pixel region, and the second electrode 21 is a common electrode for each pixel region, and the second electrode 21 is configured to function as a metal barrier wall between adjacent pixel regions. That is, multiple display structure portions 100 share the second electrode 21. The second electrode 21 of the display structure portions 100 can be integrally formed during processing and manufacturing.

[0055] Since the second electrode 21 hermetically surrounds each pixel region, the second electrode 21 performs the function of a barrier wall, allowing each pixel region to emit light independently, thereby effectively preventing optical crosstalk between pixel regions.

[0056] In addition, a pad area 28 for the second electrode is provided at the edge of the display panel. For details, see the display structure 100 at the right end located at the edge of the display panel in FIG.

[0057] With reference to the plan view shown in FIG. 3, in the following description, the arrangement of the second electrodes in the display panel provided in this embodiment of the present invention can be more intuitively understood.

[0058] FIG. 3 is a plan view corresponding to FIG. 2, according to one embodiment of the present invention.

[0059] As can be seen from Figure 3, each Light-emitting layer 23 corresponds to one pixel region, and pixelated routing is arranged with the pixel region and the second electrode 21. That is, each pixel region is surrounded by the second electrode 21, and the second electrodes 21 of all pixel regions are connected. That is, the second electrode 21 functions as a common electrode for all display structure units 100. As can be seen from FIG. 3, the second electrode 21 is routed around each pixel region in a sealed state, which can effectively block light between adjacent pixel regions.

[0060] The shape of the second electrode corresponding to each pixel region is not particularly limited in this embodiment of the present invention. The shape of the second electrode may be any one of a triangle, a rectangle, a circle, a polygon, or another shape. Details will not be described again in this specification. The rectangle includes a square. An example will be described in which the shape of the second electrode 21 routed around the pixel region shown in FIG. 2 is rectangular.

[0061] 3, it can be intuitively seen that the second electrode 21 functions as a barrier wall for each pixel region, preventing mutual optical crosstalk between the pixel regions, thereby realizing the function of optical isolation. Therefore, the special process for providing a separate barrier wall, which is required in the structure shown in FIG. 1, is not required. The display panel provided in this embodiment of the present invention reduces the process flow and is easy to implement in engineering.

[0062] Therefore, the micro LED display panel provided in this embodiment of the present invention uses a vertically structured chip architecture. The first electrode and the second electrode are disposed on the top and bottom surfaces of the chip, respectively. In this way, there is no need to etch the light-emitting region to expose the second electrode, and the area of ​​the light-emitting region is not wasted, thereby increasing the area of ​​the light-emitting region and facilitating improved light efficiency. Furthermore, since mass transfer is not required in the semiconductor process due to the vertical structure, product certification rates can be ensured. Additionally, the second electrode in this embodiment of the present invention is a common electrode and is routed around the pixel regions. Specifically, the second electrode can function as a metal barrier wall between pixel regions to prevent optical crosstalk between pixel regions and facilitate pixelated routing of the second electrode. This can result in more uniform current distribution and more uniform brightness of the display panel. No special procedures are required for the barrier wall fabrication process, which reduces process flow and facilitates engineering.

[0063] Referring to FIG. 2, the side surfaces of the second electrode 21 are inclined, with an inclination angle ranging from 30 degrees to 150 degrees. The inclination angle of the side surfaces of the second electrode 21 shown in FIG. 2 is an acute angle. That is, the cross section of the second electrode 21 shown in FIG. 2 is a regular trapezoid. It should be understood that the inclination angle may be an obtuse angle, and the cross section of the second electrode 21 correspondingly has an inverted trapezoid shape.

[0064] Second electrode 21 side surface is designed with an inclination, which helps to collect light and improve light efficiency.

[0065] In addition, according to the micro LED display panel provided in this embodiment of the present invention, the sidewalls of the display structure are inclined, with an inclination angle ranging from 30 degrees to 150 degrees. When the sidewalls match the inclination angle of the side of the second electrode, light can be collected, and the inclination of the sidewalls helps to drain a current and prevent current congestion.

[0066] In this embodiment of the present invention, the side of the second electrode surface The tilt angle of the structure is displayed side wall For example, the second electrode may have an inverted trapezoidal shape, and the sidewall of the display structure may have a regular trapezoidal shape.

[0067] Furthermore, in order to improve light emission efficiency and reduce light reflection, the surface of the second semiconductor away from the light emitting layer exhibits a crystalline structure. The specific shape of the crystalline structure is not particularly limited in this embodiment of the present invention. For example, it may be sawtooth as shown in FIG. 2, or wavy. If the surface of the second semiconductor away from the light emitting layer is flat, the emitted light will be reflected, and the light emission will be affected.

[0068] Hereinafter, with reference to the accompanying drawings, several specific implementation forms of the second electrode of the micro LED display panel provided in the embodiments of the present invention will be described.

[0069] FIG. 4a is a diagram illustrating another cross section of a micro LED display panel according to one embodiment of the present invention.

[0070] To further separate light between adjacent display structures, the side of the second electrode that contacts the second semiconductor layer is partially or completely embedded in the second semiconductor layer.

[0071] In FIG. 4a, the side of the second electrode 21 that contacts the second semiconductor layer 22 is partially embedded in the second semiconductor layer 22. In addition, the depth to which the second electrode 21 is embedded in the second semiconductor layer 22 is not particularly limited in this embodiment of the present invention. It should be understood that the greater the depth to which the second electrode 21 is embedded, the poorer the light-blocking effect. For example, after the second electrode 21 is embedded in the second semiconductor layer 22, it may contact the passivation layer 29, as shown in FIG. 4b. In this case, the second semiconductor layers 22 between the display structures are no longer connected but are separated by the second electrode 21.

[0072] It can be seen that the side of the second electrode 21 in contact with the second semiconductor layer 22 can be completely embedded within the second semiconductor layer 22, as shown in FIG.

[0073] In addition, the specific shape of the second electrode 21 embedded in the second semiconductor layer 22 is not particularly limited in this embodiment of the present invention. Those skilled in the art can set the shape based on actual requirements.

[0074] According to the display panel provided in this embodiment of the present invention, the second electrode 21 is used to perform the function of a barrier wall to achieve optical isolation between pixel regions. In other words, the process of preventing optical crosstalk can be completed at the chip level, which can improve the product yield. Furthermore, the chip Size is continuously adapted to cover applications in multiple scenarios, e.g., tens of thousands of pixels, millions of pixels, or even tens of millions of pixels. reduction It can be done.

[0075] Furthermore, a bonding layer 27 is provided between the display structures for filling purposes. The bonding layer 27 is non-conductive, so that it can achieve electrical insulation and improve the strength of the display panel.

[0076] The first electrode 25 is a surface electrode, and covers the surface and sidewalls of the first semiconductor layer 24 .

[0077] The second semiconductor layers of the display structures are communicated, and the thickness of the second semiconductor layer at the joint of adjacent display structures may be greater than a coarsening depth to prevent chip breakage.

[0078] A passivation layer 29 is deposited on the etched ends of the second semiconductor layer 22, the light emitting layer 23, and the first semiconductor layer 24. The side of the second electrode 21 that is buried in the second semiconductor layer 22 is in contact with the passivation layer 29.

[0079] The chemical properties of the passivation layer 29 are stable, so the passivation layer 29 can achieve a protective function.

[0080] The first electrode 25 of the display panel provided in this embodiment of the present invention includes an ohmic electrode and a reflective electrode.

[0081] The ohmic electrode is configured to connect to the first semiconductor layer 24 .

[0082] The reflective electrode is connected to a driving circuit, and in particular to a switch, via a metal solder joint. The reflective electrode is further configured to reflect light.

[0083] In order to further improve the transmittance, the display panel provided in this embodiment of the present invention further comprises a transparent conductive layer, which will be described in detail below with reference to the accompanying drawings.

[0084] FIG. 6 illustrates yet another cross-section of a micro LED display panel according to an embodiment of the present invention.

[0085] As can be seen from FIG. 6, the display panel further includes a transparent conductive layer 30 disposed between the second semiconductor layer 22 and the second electrode 21.

[0086] The side of the second electrode 21 that contacts the transparent conductive layer 30 is at least partially embedded in the transparent conductive layer 30. To improve the light-shielding effect of the second electrode 21, the second electrode may be embedded in the transparent conductive layer 30, or may be embedded in the transparent conductive layer 30 and the second semiconductor layer 22. For details, see FIG. 7 , which is a further cross-sectional view of a micro LED display panel according to an embodiment of the present invention. In FIG. 7 , the lower end of the second electrode 21 penetrates the transparent conductive layer 30 and is embedded in the second semiconductor layer 22.

[0087] To reduce the ohmic resistance between the second semiconductor layer 22 and the second electrode 21, a transparent conductive layer 30 is added to the surface of the second semiconductor layer 22, and then the second electrode 21 is formed on the transparent conductive layer 30.

[0088] According to the display panel provided in this embodiment of the present invention, a transparent conductive layer 30 is added. The transparent conductive layer 30 functions as a transition between the second electrode and the second semiconductor layer, solving the problem of ohmic contact between metal and semiconductor and reducing resistance. In addition, the transparent conductive layer 30 is distributed over the entire surface, helping to spread current more evenly and improving light efficiency, thereby avoiding the problem of uneven brightness and improving the reliability of the display panel. In addition, the transparent conductive layer 30, combined with the pixelated and routed second electrode 21, can reduce power, voltage, and power consumption.

[0089] The material of the transparent conductive layer 30 is not particularly limited in this embodiment of the present invention. For example, indium tin oxide (ITO), indium zinc oxide (IZO), etc. may be selected as the transparent conductive layer.

[0090] The transparent conductive layer 30 provided in this embodiment of the present invention may be disposed separately. Alternatively, the transparent conductive layer 30 may be used in combination with the sawtooth crystal structure shown in FIG. 5 to improve luminous efficiency. This is not particularly limited in the embodiment of the present invention.

[0091] In order to allow those skilled in the art to better understand the micro LED display panel provided in the embodiments of the present invention, the manufacturing process will be described in detail below with reference to the accompanying drawings. Referring to the manufacturing process, it can be more clearly understood that the technical solutions provided in the embodiments of the present invention reduce the process flow and are easy to implement in engineering.

[0092] FIG. 8 illustrates the structure of the first step in the manufacturing process of a micro LED display panel according to one embodiment of the present invention.

[0093] On the substrate 81, the first semiconductor layer 24, the light emitting layer 23, and the second semiconductor layer 22 are laminated in this order.

[0094] First, the wafer surface of the epitaxial wafer is cleaned to ensure that the surface is clean.

[0095] FIG. 9 is a diagram illustrating the structure of a second step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention.

[0096] The photo-etched chip is then subjected to inductively coupled plasma (ICP) dry etching. The first semiconductor layer 24, the light-emitting layer 23, and the second semiconductor layer 22 are etched to form a penetrated first semiconductor layer 24 and light-emitting layer 23, and a partially penetrated second semiconductor layer 22. That is, a portion of the second semiconductor layer 22 is not penetrated, and the second semiconductor layer 22 of the display structure is connected. A passivation layer 29 is then deposited. The passivation layer 29 has stable chemical properties, and therefore can provide a protective function.

[0097] A first electrode 25 is formed on the side of the first semiconductor layer 24 away from the light-emitting layer 23, which may specifically include drilling holes for depositing an ohmic electrode, followed by evaporation on a reflective electrode. Both the ohmic electrode and the reflective electrode belong to the first electrode 25. The ohmic electrode is configured to connect to a switch. The reflective electrode is configured to reflect light and connect to the first semiconductor layer 24.

[0098] A specific manufacturing process for the second electrode will be described below.

[0099] FIG. 10 is a diagram illustrating the structure of a third step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention.

[0100] Second semiconductor layer 22 A second electrode 21 is formed on the side of the pixel region away from the light-emitting layer 23, and the second electrode 21 is routed around the periphery of each pixel region, the second electrode 21 being a common electrode for each pixel region, and the second electrode 21 serving as a metal barrier wall between adjacent pixel regions.

[0101] The wafer is bonded to the first substrate 101 via the bonding layer 27, and the original substrate is removed to expose the second semiconductor layer 22. A pixelated metal routing is fabricated on the second semiconductor layer 22, and a crystal structure process such as roughening is completed on the second electrode 21 and areas other than the second electrode 21. In FIG. 10, the sawtooth shape of the surface of the second semiconductor layer 22 indicates a roughened structure, which can reduce the total reflection of the emitted light and improve the light-emitting efficiency. The surface of the second semiconductor layer 22 can also use other crystal structure shapes, and the details will not be described again here.

[0102] FIG. 11 is a diagram illustrating the structure of a fourth step in the manufacturing process of a micro LED display panel according to an embodiment of the present invention.

[0103] Another bonding step is performed to transfer the chip to the second substrate 102, after which the first substrate is removed to expose the first electrodes 25.

[0104] After the first electrode 25 is exposed, see FIG. 2. The first electrode 25 is connected to the metal solder joint of the switch through a bonding process, so that the chip can be integrated with the drive circuit of the switch and then directly packaged. The display panel provided in this embodiment of the present invention can be directly encapsulated without requiring mass transfer.

[0105] Based on the micro LED display panel provided in the above embodiment, an embodiment of the present invention further provides a display device. The display device provided in this embodiment of the present invention will be described below with reference to the accompanying drawings.

[0106] FIG. 12 shows a display device according to one embodiment of the present invention.

[0107] The specific application scenario of the display device 1000 is not particularly limited in this embodiment of the present invention. For example, the display device 1000 may be a display screen, or may be an electronic device having a display screen, such as an AR product, a VR product, or a smart vehicle light.

[0108] The display device 1000 provided in this embodiment of the present invention includes the micro LED display panel 803 described in the previous embodiments, and further includes a driving circuit 802 and a controller 801.

[0109] The micro LED display panel 803 further includes a plurality of switches, each of which corresponds to a corresponding switch, and the switches are configured to control whether the luminous areas emit light.

[0110] Each display structure is connected to a corresponding switch. Each display structure corresponds to a pixel area, and the display structure is arranged in an array. The display device provided in this embodiment of the present invention does not particularly limit the size of the display panel. The size may be set based on actual requirements. In addition, the number of display structure in the display panel is also not limited.

[0111] The controller 801 is configured to control the driving circuit 802 to drive the state of the switch of the micro LED display panel. When the switch is turned on, the light-emitting layer emits light.

[0112] In an actual product, the controller 801 and the driving circuit 802 may be disposed on a control integrated circuit IC, which is configured to control a micro LED display panel 803 for display.

[0113] The display device provided in this embodiment of the present invention includes the above-mentioned micro LED display panel, which uses a vertical chip architecture to increase the area of ​​the light-emitting region. This helps improve light efficiency and reduce product size, allowing more electrons and holes to be accommodated per unit area. The second electrode is a common electrode, routed around the periphery of the pixel area, and can function as a metal barrier between pixel areas to prevent optical crosstalk between them. This results in more uniform current distribution and brightness. No special procedures are required for the barrier wall fabrication process, and no complex mass transfer process is required, which reduces the process flow and facilitates product implementation. When the switch is a CMOS switch, the switch is particularly suitable for applications requiring high current and high pixel density, facilitating product size reduction.

[0114] Based on the micro LED display panel and display device provided in the above embodiments, one embodiment of the present invention further provides a manufacturing method for a micro LED display panel, which will be described in detail below with reference to the accompanying drawings.

[0115] FIG. 13 is a flowchart of a method for manufacturing a micro LED display panel according to an embodiment of the present invention.

[0116] An embodiment of the present invention provides a method for manufacturing a micro LED display panel, which includes the following steps.

[0117] S1301: Obtain a first semiconductor layer, a light emitting layer, and a second semiconductor layer that are stacked in order. First, the wafer surface of the epitaxial wafer is cleaned to ensure that the surface is clean.

[0118] S1302: Etching the first semiconductor layer, the light emitting layer, and the second semiconductor layer to form a penetrated first semiconductor layer and light emitting layer and a partially penetrated second semiconductor layer. ICP dry etching can be used to perform the etching.

[0119] S1303: Forming a first electrode on the side of the first semiconductor layer away from the light-emitting layer. Forming the first electrode specifically includes: opening a hole for depositing an ohmic electrode on the side of the first semiconductor layer away from the light-emitting layer, and performing evaporation on the reflective electrode, so that the first electrode comprises an ohmic electrode and a reflective electrode. The ohmic electrode is configured to be connected to a switch. The reflective electrode is configured to reflect light and to be connected to the first semiconductor layer.

[0120] Before forming the first electrode, the method further includes depositing a passivation layer, the chemical properties of which are stable, and therefore the passivation layer can achieve a protection function.

[0121] S1304: Forming a second electrode on a side of the second semiconductor layer away from the light-emitting layer, the second electrode being routed around the periphery of each pixel region, the second electrode being a common electrode for each pixel region, and the second electrode serving as a metal barrier wall between adjacent pixel regions.

[0122] The step of forming a second electrode on the side of the second semiconductor layer away from the light-emitting layer specifically includes: bonding the display panel to the first substrate via a bonding layer to expose the second semiconductor layer; and forming a second electrode on the second semiconductor layer by routing around each pixel area.

[0123] After forming the second electrode, the method further includes: performing bonding to transfer the display panel to a second substrate; and removing the first substrate to expose the first electrode.

[0124] After the first electrode is exposed, the first electrode is connected to the metal solder joint of the switch through a bonding process, so that the chip can be integrated with the driving circuit of the switch and then directly packaged.

[0125] For specific steps of the manufacturing method of the micro LED display panel, please refer to the descriptions of Figures 8 to 10. The details will not be described again in this specification.

[0126] Therefore, according to the method for manufacturing a micro LED display panel provided in this embodiment of the present invention, the reflective electrode of the first electrode is fabricated on the first semiconductor layer, and the pixelated second electrode is fabricated on the second semiconductor layer. That is, only pixelated metal routing is performed on the second electrode. The second electrode functions as a barrier wall between pixel regions, eliminating the need for specially fabricated barrier walls, thereby reducing process flow. Finally, the chip is bonded to a silicon-based CMOS switch. Display panels manufactured using the method of the present invention can be directly integrated with the switch without requiring mass transfer and then directly packaged, reducing process flow and facilitating commercialization.

[0127] In the present invention, it should be understood that "at least one (item)" refers to one or more, and "multiple" refers to two or more. The term "and / or" is used to describe a relationship between related objects and indicates that three relationships may exist. For example, "A and / or B" can represent the following three cases: only A is present, only B is present, or both A and B are present, and A and B may be singular or plural. The character " / " generally indicates an "or" relationship between related objects. Furthermore, "at least one of the following items (pieces)" or similar expressions refers to any combination of these items, including any combination of a single item (piece) or multiple items (pieces). For example, "at least one item (piece)" of a, b, or c may refer to a only, b only, c only, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

[0128] The foregoing description is a mere illustration of the present invention. fruitThe above embodiments are merely examples and are not intended to limit the present invention in any way. Although preferred embodiments of the present invention have been disclosed above, the embodiments are not intended to limit the present invention. By using the methods and technical content disclosed above, those skilled in the art can make multiple possible modifications and changes to the technical solutions of the present invention, or can amend the technical solutions to become embodiments with equivalent effects through equivalent variations without departing from the protection scope of the technical solutions of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments in accordance with the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A micro LED display panel comprising a plurality of display structures, each display structure comprising a first electrode, a second electrode, a first semiconductor layer, a second semiconductor layer, and a light emitting layer; the first electrode, the first semiconductor layer, and the light-emitting layer of adjacent display structures are independent of each other; the first semiconductor layer and the second semiconductor layer are respectively disposed on surfaces on two sides of the light emitting layer, the first electrode is disposed on a side of the first semiconductor layer away from the light emitting layer, and the second electrode is disposed on a side of the second semiconductor layer away from the light emitting layer; the light-emitting layer of each display structure corresponds to one pixel region, the second electrode is routed around the periphery of each pixel region, the second electrode being a common electrode for each pixel region, and the second electrode being configured to serve as a metal barrier wall between adjacent pixel regions; Display panel.

2. The side surface of the second electrode is inclined, and the inclination angle ranges from 30 degrees to 150 degrees. The display panel according to claim 1 .

3. The sidewalls of the display structure are inclined, and the inclination angle ranges from 30 degrees to 150 degrees. The display panel according to claim 2.

4. the second electrode in contact with the second semiconductor layer is partially or completely buried in the second semiconductor layer; 3. The display panel according to claim 1.

5. a passivation layer is deposited on the second semiconductor layer, the light emitting layer, and the etched ends of the first semiconductor layer; a side of the second electrode that is buried in the second semiconductor layer in contact with the passivation layer; 5. The display panel according to claim 4.

6. further comprising a transparent conductive layer disposed between the second semiconductor layer and the second electrode; The display panel according to claim 1 .

7. the side of the second electrode in contact with the transparent conductive layer is at least partially embedded in the transparent conductive layer; or a side of the second electrode in contact with the transparent conductive layer being at least partially buried in the transparent conductive layer and the second semiconductor layer; 7. The display panel according to claim 6.

8. The surface of the second semiconductor away from the light emitting layer exhibits a crystalline structure.

6. The display panel according to claim 1.

9. the first electrode is a surface electrode; the first electrode envelops the surface and sidewalls of the first semiconductor; the display panel further comprises a plurality of switches; Each display structure corresponds to one switch; The first electrode is configured to connect to a corresponding switch. The display panel according to claim 1 .

10. the second semiconductor layer of the display structure is connected; the first semiconductor layer and the second semiconductor layer are carrier transport layers, the charge polarity of the first semiconductor layer is the same as the polarity of the first electrode; The charge polarity of the second semiconductor layer is the same as the polarity of the second electrode. The display panel according to claim 1 .

11. the first electrode comprises an ohmic electrode and a reflective electrode; the ohmic electrode is configured to connect to the first semiconductor layer; the reflective electrode is connected to a driving circuit; the reflective electrode is further configured to reflect light. The display panel according to any one of claims 1 to 10.

12. The shape of the second electrode is any one of a triangle, a rectangle, a circle, and a polygon. The display panel according to any one of claims 1 to 11.

13. A display device comprising a micro LED display panel according to any one of claims 1 to 12, The display device further comprises a drive circuit and a controller; Each display structure is connected to a corresponding switch; the controller is configured to control the drive circuit to drive the state of the switch; When the switch is turned on, the light-emitting layer emits light. Display device.

14. the switch is a complementary metal oxide semiconductor CMOS switch or a thin film transistor (TFT); 14. The display device according to claim 13.

15. A method for manufacturing a micro LED display panel, comprising: Obtaining a first semiconductor layer, a light emitting layer, and a second semiconductor layer that are sequentially stacked; Etching the first semiconductor layer, the light emitting layer, and the second semiconductor layer to form the first semiconductor layer and the light emitting layer penetrated and the second semiconductor layer partially penetrated; forming a first electrode on a side of the first semiconductor layer away from the light emitting layer; forming the second electrode on a side of the second semiconductor layer away from the light emitting layer, the second electrode being routed around the periphery of each pixel region, the second electrode being a common electrode for each pixel region, and the second electrode serving as a metal barrier wall between adjacent pixel regions; method.

16. The step of forming the first electrode includes: opening a hole and depositing an ohmic electrode on the side of the first semiconductor layer away from the light emitting layer; performing deposition on a reflective electrode, wherein the first electrode comprises the ohmic electrode and the reflective electrode; 16. The method of claim 15.

17. Before the step of forming the first electrode, the method further comprises the step of depositing a passivation layer.

17. The method of claim 15 or 16.

18. The step of forming the second electrode on the second semiconductor layer on a side away from the light emitting layer includes: bonding the display panel to a first substrate via a bonding layer to expose the second semiconductor layer; forming the second electrode on the second semiconductor layer by routing around the periphery of each pixel area; 16. The method of claim 15.

19. After the step of forming the second electrode, the method further comprises: bonding and transferring the display panel to a second substrate; removing the first substrate to expose the first electrode; connecting the first electrode to a corresponding switch; 20. The method of claim 18.

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