Micro light emitting diode display structure

Abstract

The application relates to the micro display technical field and discloses a micro light emitting diode display structure. The micro light emitting diode display structure comprises a driving backboard, a plurality of first LED units and a plurality of second LED units. The plurality of first LED units are arranged on the driving backboard at intervals. Each first LED unit can be individually driven by the driving backboard. The first LED unit emits first color light. The plurality of second LED units are one-to-one correspondingly stacked on the plurality of first LED units. Each second LED unit can be individually driven by the driving backboard. The second LED unit emits mixed color light, and the mixed color light comprises second color light and third color light. Wherein, the first color light, the second color light and the third color light are all different. One first LED unit and the second LED unit stacked above the first LED unit constitute a full-color pixel point. The application can improve the service life and display effect of the display structure.

Description

Technical Field

[0001] This application belongs to the field of micro-display technology, specifically relating to a micro light-emitting diode display structure. Background Technology

[0002] Micro-LEDs are high-density integrated LED arrays achieved through LED miniaturization and matrixing. The distance between LED units ranges from 0.1 to 110 micrometers, allowing for a greater number of LEDs to be integrated onto a chip of the same area, thus achieving high resolution and high contrast.

[0003] In related technologies, Micro-LED display structures achieve RGB full-color display through color conversion using quantum dot photoresist. However, in practical applications, the organic components in the quantum dot photoresist are susceptible to environmental influences, leading to material aging, reduced lifespan of the Micro-LED display structure, and decreased display performance. Utility Model Content

[0004] This application aims to address at least one of the technical problems existing in the prior art or related technologies.

[0005] Therefore, this application provides a micro-LED display structure, including: a driving backplane; a plurality of first LED units, spaced apart on the driving backplane, each first LED unit being individually driven by the driving backplane, the first LED unit including a first doped semiconductor layer, a first active layer, and a second doped semiconductor layer, the first LED unit emitting a first color light; a plurality of second LED units, stacked one-to-one on the plurality of first LED units, each second LED unit being individually driven by the driving backplane, the second LED unit including a first doped semiconductor layer, a second active layer, and a second doped semiconductor layer, the second LED unit emitting mixed color light, the mixed color light including a second color light and a third color light; the first color light, the second color light, and the third color light are all different; wherein, one first LED unit and the second LED units stacked on top of the first LED unit constitute a full-color pixel.

[0006] In one possible implementation, the driving backplane includes a driving circuit having a plurality of first contacts and at least one second contact. The micro LED display structure further includes a first conductive post and a second conductive post bonded to the first conductive post. A portion of the first contacts is electrically connected to a first doped semiconductor layer of the corresponding first LED unit. A portion of the first contacts is electrically connected to the corresponding first conductive post, and the second conductive post bonded to the first conductive post is electrically connected to the first doped semiconductor layer of the corresponding second LED unit. The second doped semiconductor layers of the plurality of first LED units and the second doped semiconductor layers of the plurality of second LED units are electrically connected together to the second contacts.

[0007] In one possible implementation, the micro LED display structure further includes: a first electrode layer disposed between the second conductive post and the corresponding second LED unit, for electrically connecting the second conductive post and the corresponding second LED unit to a first doped semiconductor layer.

[0008] In one possible implementation, the micro LED display structure further includes: a bonding layer disposed between the driving backplate and the plurality of first LED units; and a second electrode layer disposed between the bonding layer and the corresponding first LED unit for electrically connecting the first contact and the first doped semiconductor layer of the corresponding first LED unit.

[0009] In one possible implementation, the micro LED display structure further includes: a third electrode layer disposed on a plurality of first LED units and electrically connected to the second doped semiconductor layer of the plurality of first LED units; and a third conductive post, one end of which is electrically connected to the second contact and the other end of which is electrically connected to the third electrode layer.

[0010] In one possible implementation, the micro LED display structure further includes: a fourth electrode layer disposed on a plurality of second LED units and electrically connected to the second doped semiconductor layer of the plurality of second LED units; and a fourth conductive post, one end of which is electrically connected to the fourth electrode layer and the other end of which is electrically connected to the third electrode layer.

[0011] In one possible implementation, the micro LED display structure further includes: a first filler layer disposed on the driving backplane, covering at least a plurality of the first LED units and a plurality of the first conductive pillars, and exposing at least the top surfaces of the plurality of the first conductive pillars; a second filler layer bonded to the first filler layer, the second filler layer having a plurality of the second conductive pillars; and the second LED units disposed above the second filler layer such that the first LED units are spaced apart from the second LED units stacked above the first LED units; wherein, when the second filler layer is bonded to the first filler layer, the plurality of the second conductive pillars are bonded one-to-one with the plurality of the first conductive pillars.

[0012] In one possible implementation, the first conductive post includes a first post segment and a second post segment connected to each other, and the first filling layer includes: a first layer disposed on the driving backplate, covering at least a plurality of the first LED units, wherein the first post segment is formed on the first layer and electrically connected to the corresponding first contact; and a second layer disposed on the first layer, wherein the second post segment is formed on the second layer, wherein one end of the second post segment is electrically connected to the corresponding first post segment and the other end is electrically connected to the corresponding second conductive post.

[0013] In one possible implementation, the spacing between the first LED unit and the second LED unit stacked above the first LED unit is 100 nm to 2 μm.

[0014] In one possible implementation, the first LED unit and a second LED unit stacked above the first LED unit are coaxially arranged. The first conductive post and the second conductive post are located directly above the corresponding first contact. The projections of the second LED unit and the corresponding first contact on the drive backplane do not overlap.

[0015] The miniature light-emitting diode display structure provided in this application can achieve at least the following technical effects:

[0016] In this application, multiple second LED units are stacked one-to-one on multiple first LED units. That is, a second LED unit is stacked directly above each first LED unit, so that a single first LED unit and the second LED units stacked above it constitute a full-color pixel. This achieves color mixing in vertical space, reduces the light-emitting area of ​​the full-color pixel, increases brightness, and also achieves higher full-color resolution and reduced pixel pitch. Each first LED unit and each second LED unit can be driven independently by a driving backplate, improving display performance. The first LED unit emits a first color light, and the second LED unit emits mixed-color light, which includes a second color light and a third color light. The first, second, and third colors are all different, achieving full-color display. Compared to the color conversion method in related technologies, this application, by having a first LED unit emit a first color light and a second LED unit emit mixed-color light, with a single first LED unit and the second LED units stacked above it constituting a full-color pixel, can improve the lifespan of the display structure and the display effect.

[0017] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0018] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:

[0019] Figure 1 This is a schematic diagram of the planar structure of the micro light-emitting diode display structure provided in the embodiments of this disclosure;

[0020] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure along line A1-A2 provided in the illustrated embodiment;

[0021] Figure 3 A schematic structural diagram of a first epitaxial wafer provided in one embodiment of this disclosure;

[0022] Figure 4 This is a schematic structural diagram showing the second step of the fabrication method of the micro light-emitting diode display structure provided in an embodiment of this disclosure.

[0023] Figure 5 This is a schematic structural diagram showing the third step of the fabrication method of the micro light-emitting diode display structure provided in one embodiment of the present disclosure.

[0024] Figure 6This is a schematic structural diagram showing the result of step 4 of the fabrication method for a micro light-emitting diode display structure provided in an embodiment of this disclosure.

[0025] Figure 7 This is a schematic structural diagram showing the result of step 5 of the fabrication method for a micro light-emitting diode display structure provided in one embodiment of this disclosure.

[0026] Figure 8 A schematic planar structural diagram showing the result of step 6 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure;

[0027] Figure 9 for Figure 8 A schematic diagram of the B1-B2 cross-sectional structure of the embodiment shown;

[0028] Figure 10 This is a schematic structural diagram showing the result of step 7 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure.

[0029] Figure 11 A schematic structural diagram of a second epitaxial wafer provided in one embodiment of this disclosure;

[0030] Figure 12 This is a schematic structural diagram showing the result of step 9 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure.

[0031] Figure 13 This is a schematic structural diagram showing the result of step 10 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure.

[0032] Figure 14 This is a schematic structural diagram showing the result of step 11 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure.

[0033] Figure 15 A schematic structural diagram showing the result of step 12 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure;

[0034] Figure 16 This is a schematic structural diagram showing the result of step 13 of the method for fabricating a micro light-emitting diode display structure according to an embodiment of this disclosure.

[0035] Figure 17 This is a schematic structural diagram showing the result of step 14 of the method for fabricating a micro-light-emitting diode display structure according to an embodiment of this disclosure.

[0036] Figure 18 This is a schematic diagram of the structure of a display device provided in an embodiment of this disclosure.

[0037] The reference numerals in the attached figures are as follows:

[0038] 100: Miniature LED display structure;

[0039] 101: Driver backplane; 1011: First contact; 1012: Second contact; 102: First LED unit; 103: Second LED unit; 104: First conductive post; 1041: First post segment; 1042: Second post segment; 105: Second conductive post; 106: First filler layer; 1061: First layer; 1062: Second layer; 107: Second filler layer; 108: First electrode layer; 109: Bonding layer; 110: Second electrode layer; 111: Third conductive pillar; 112: Third electrode layer; 113: Fourth electrode layer; 114: First epitaxial wafer; 1141: First substrate; 1142: First epitaxial structure; 1143: First current spreading layer; 1144: Bonding metal layer; 115: Second epitaxial wafer; 1151: Second substrate; 1152: Second epitaxial structure; 1153: Second current spreading layer; 116: Leveling layer; 117: Third leveling layer; 118: Fourth conductive pillar;

[0040] 200: Display device. Detailed Implementation

[0041] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0042] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0043] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better describing the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this disclosure according to the specific circumstances.

[0044] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0045] Unless otherwise stated, the term "multiple" means two or more.

[0046] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0048] It should be noted that, as used in the embodiments of this disclosure, the term "layer" refers to a portion of material comprising a region having a certain thickness. A layer may extend over the entire lower or upper structure, or may have a extent smaller than that of the lower or upper structure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure, with a thickness less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of a continuous structure, or between any pair of horizontal planes therebetween. A layer may extend horizontally, vertically, and / or along a conical surface.

[0049] It should be noted that the term "micro" as used in the embodiments of this disclosure refers to the descriptive size of certain devices or structures according to the embodiments of this application. The term "micro" as used herein is intended to indicate a scale of 0.1 to 100 μm. However, it should be understood that the embodiments of this application are not necessarily limited thereto, and certain aspects of the embodiments can be applied to larger and possibly smaller size scales.

[0050] like Figures 1 to 17 As shown, this embodiment of the present disclosure provides a micro LED display structure 100, including a driving backplane 101, a plurality of first LED units 102, and a plurality of second LED units 103. The plurality of first LED units 102 are spaced apart on the driving backplane 101. Each first LED unit 102 can be driven individually by the driving backplane 101. Each first LED unit 102 includes a first doped semiconductor layer, a first active layer, and a second doped semiconductor layer. The first LED unit 102 emits a first color light. A plurality of second LED units 103 are stacked one-to-one on the plurality of first LED units 102. Each second LED unit 103 can be driven individually by the driving backplane 101. Each second LED unit 103 includes a first doped semiconductor layer, a second active layer, and a second doped semiconductor layer. The second LED unit 103 emits mixed-color light, which includes a second color light and a third color light. The first color light, the second color light, and the third color light are all different. A first LED unit 102 and a second LED unit 103 stacked on top of the first LED unit 102 constitute a full-color pixel.

[0051] It should be noted that, for ease of description, the "miniature light-emitting diode display structure" will be referred to as a "display structure" in the following description. Figure 2 As shown, the direction from bottom to top is the vertical direction.

[0052] Multiple first LED units 102 are spaced apart on the driving backplate 101, and multiple second LED units 103 are stacked one-to-one on the multiple first LED units 102, so that each first LED unit 102 can be driven by the driving backplate 101 individually, and each second LED unit 103 can be driven by the driving backplate 101 individually, thereby improving the display effect.

[0053] Multiple second LED units 103 are stacked one-to-one on multiple first LED units 102. That is, a second LED unit 103 is stacked directly above each first LED unit 102. This allows each first LED unit 102 and the second LED unit 103 directly above it to be coaxially arranged. Furthermore, a first LED unit 102 and the second LED units 103 stacked above it can constitute a full-color pixel. This enables color mixing in vertical space, reduces the light-emitting area of ​​the full-color pixel, increases brightness, achieves higher full-color resolution, and reduces pixel pitch.

[0054] In practical applications, each first LED unit 102 and the second LED unit 103 directly above it can form an LED unit group, and at least one LED unit group constitutes a full-color pixel.

[0055] The first LED unit 102 includes a first doped semiconductor layer, a first active layer, and a second doped semiconductor layer. Specifically, the first doped semiconductor layer can be a p-type semiconductor layer. The p-type semiconductor layer can be formed by doping or ion implantation, for example, p-type gallium nitride (GaN). The second doped semiconductor layer can be an n-type semiconductor layer. The n-type semiconductor layer can be formed by doping or ion implantation, for example, n-type GaN. The first active layer is disposed between the first doped semiconductor layer and the second doped semiconductor layer, for enabling the first LED unit 102 to directly emit a first color light. For example, the first active layer includes an indium gallium nitride (InGaN) quantum well to generate the first color light, for example, red light.

[0056] The second LED unit 103 comprises a first doped semiconductor layer, a second active layer, and a second doped semiconductor layer. Specifically, the first doped semiconductor layer can be a p-type semiconductor layer. The p-type semiconductor layer can be formed by doping or ion implantation, for example, p-type gallium nitride (GaN). The second doped semiconductor layer can be an n-type semiconductor layer. The n-type semiconductor layer can be formed by doping or ion implantation, for example, n-type GaN. The second active layer is disposed between the first and second doped semiconductor layers and is used to enable the second LED unit 103 to directly emit mixed-color light. For example, the second active layer includes a first quantum well and a second quantum well. The first quantum well is used to enable the second LED unit 103 to emit a second color light (e.g., blue light), and the second quantum well is used to enable the second LED unit 103 to emit a third color light (e.g., green light), thereby enabling the second LED unit 103 to emit mixed-color light. The first quantum well includes a well and a barrier. The second quantum well includes a well and a barrier.

[0057] The first LED unit 102 directly emits first-color light, achieving more efficient first-color light emission. The second LED unit 103 directly emits mixed-color light, which includes second-color and third-color light, achieving more efficient second-color and third-color light emission. Since the first, second, and third colors are all different, full-color display is possible. Compared to color conversion methods in related technologies, this embodiment uses the first LED unit 102 to directly emit first-color light and the second LED unit 103 to directly emit mixed-color light. One first LED unit 102 and the second LED unit 103 stacked above it constitute a full-color pixel, improving the lifespan, display effect, and reliability of the display structure.

[0058] Furthermore, the first LED unit 102 emits light of the first color, and the second LED unit 103 emits mixed-color light. The second LED unit 103 can be stacked on the first LED unit 102 through two wafer bonding processes to complete the fabrication of the display structure 100, thereby reducing the complexity of the process and improving the yield.

[0059] In this embodiment, the driving backplane 101 refers to the material on which subsequent material layers are added. The driving backplane 101 itself may be patterned. The material added to the top of the driving backplane 101 may be patterned or may remain unpatterned. The driving backplane 101 may include a wide variety of semiconductor materials, such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, and indium phosphide. Alternatively, the driving backplane 101 may be made of a non-conductive material, such as glass, plastic, or sapphire wafer. Further alternatively, the driving backplane 101 may have semiconductor devices or circuits formed therein.

[0060] Optionally, the first color light is red. The second color light is blue. The third color light is green.

[0061] Optionally, the first color light is red. The second color light is green. The third color light is blue.

[0062] In some embodiments, combined with Figure 1 , Figure 2 , Figures 4 to 10 , Figures 12 to 17 As shown, the driving backplane 101 includes a driving circuit having a plurality of first contacts 1011 and at least one second contact 1012. The micro LED display structure 100 also includes a first conductive post 104 and a second conductive post 105 bonded to the first conductive post 104. A portion of the first contacts 1011 is electrically connected to the first doped semiconductor layer of the corresponding first LED unit 102. A portion of the first contacts 1011 is electrically connected to the corresponding first conductive post 104, and the second conductive post 105 bonded to the first conductive post 104 is electrically connected to the first doped semiconductor layer of the corresponding second LED unit 103. The second doped semiconductor layers of the plurality of first LED units 102 and the second doped semiconductor layers of the plurality of second LED units 103 are jointly electrically connected to the second contact 1012.

[0063] In this embodiment, the term "corresponding" may refer to the corresponding connection or arrangement of structures so that each first LED unit 102 can be driven by the driving backplate 101 individually, and each second LED unit 103 can be driven by the driving backplate 101 individually, which will not be repeated below.

[0064] The driving backplane 101 includes a driving circuit with multiple first contacts 1011 and at least one second contact 1012, enabling independent control of the first LED unit 102 and the second LED unit 103 through the multiple first contacts 1011 and at least one second contact 1012. The driving backplane 101 may be provided with a circuit layer including complementary metal-oxide-semiconductor (CMOS) devices or thin-film transistor (TFT) devices, which can constitute the driving circuit.

[0065] Of the plurality of first contacts 1011, a portion of the first contacts 1011 are electrically connected to the first doped semiconductor layer of the corresponding first LED unit 102, that is, each contact 1011 is electrically connected to the first doped semiconductor layer of a first LED unit 102, so that each first LED unit 102 can be driven individually by the driving backplate 101. Another portion of the first contacts 1011 are electrically connected to the corresponding first conductive post 104, and a second conductive post 105 bonded to the first conductive post 104 is electrically connected to the first doped semiconductor layer of the corresponding second LED unit 103, that is, each first contact 1011 is electrically connected to the first doped semiconductor layer of a second LED unit 103 through the first conductive post 104 and the second conductive post 105, so that each second LED unit 103 can be driven individually by the driving backplate 101. For a certain first contact 1011, the first contact 1011 is connected to the first doped semiconductor layer of a first LED unit 102 only, or the first contact 1011 is connected to the first doped semiconductor layer of a second LED unit 103 only.

[0066] The first doped semiconductor layer of the first LED unit 102 is electrically connected to the corresponding first contact 1011. The first doped semiconductor layer of the second LED unit 103 is electrically connected to the corresponding first contact 1011. The second doped semiconductor layers of the plurality of first LED units 102 and the second doped semiconductor layers of the plurality of second LED units 103 are electrically connected to the second contact 1012, so that the driving circuit can individually drive each first LED unit 102 to emit light, and can also individually drive each second LED unit 103 to emit light.

[0067] For example, the first contact 1011 is an anode metal contact, and the second contact 1012 is a cathode metal contact. The first doped semiconductor layer is a p-type semiconductor layer. The second doped semiconductor layer is an n-type semiconductor layer. The p-type semiconductor layer of the first LED unit 102 is connected to the corresponding anode metal contact. The p-type semiconductor layer of the second LED unit 103 is connected to the corresponding anode metal contact. The n-type semiconductor layers of the first LED unit 102 and the second LED unit 103 are electrically connected to the cathode metal contact to form a common cathode structure. For each first LED unit 102, the anode metal contact can apply an anode voltage to the corresponding first LED unit 102 individually, providing a separate drive signal to control each first LED unit 102 to emit a first color light individually. For each second LED unit 103, the anode metal contact can apply an anode voltage to the corresponding second LED unit 103 individually, providing a separate drive signal to control each second LED unit 103 to emit mixed color light individually.

[0068] In one possible implementation, such as Figure 2 as well as Figures 12 to 17 As shown, the micro LED display structure 100 includes a plurality of first conductive pillars 104 and a plurality of second conductive pillars 105. The plurality of first conductive pillars 104 are spaced apart on a driving backplate 101. The plurality of second conductive pillars 105 are bonded one-to-one with the plurality of first conductive pillars 104. Each of the plurality of second conductive pillars 105 corresponds one-to-one with a first doped semiconductor layer of a plurality of second LED units 103. The end of a second conductive pillar 105 facing away from the first conductive pillar 104 is connected to the first doped semiconductor layer of the corresponding second LED unit 103.

[0069] Specifically, a first conductive post 104 is disposed on the drive back plate 101, and a second conductive post 105 is bonded to the top surface of each first conductive post 104. The second LED unit 103 can be supported by the first conductive post 104 and the second conductive post 105, so that the second LED unit 103 is stably positioned directly above the corresponding first LED unit 102.

[0070] One end of the second conductive post 105 away from the first conductive post 104 is connected to the first doped semiconductor layer of the corresponding second LED unit 103. That is, the top surface of each second conductive post 105 is connected to only one second LED unit 103, so that each second LED unit 103 can be driven individually by the drive backplate 101.

[0071] Optionally, the material of the first conductive post 104 includes, but is not limited to, copper (Cu) or tungsten (W).

[0072] Optionally, the material of the second conductive post 105 includes, but is not limited to, copper (Cu) or tungsten (W).

[0073] Optionally, such as Figure 2 , Figures 12 to 17 As shown, the first conductive post 104 is disposed above the corresponding first contact 1011 at least.

[0074] In some embodiments, such as Figure 2 , Figures 15 to 17 As shown, the micro LED display structure 100 also includes a first electrode layer 108. The first electrode layer 108 is disposed between the second conductive post 105 and the corresponding second LED unit 103, and the first electrode layer 108 is used to electrically connect the second conductive post 105 and the first doped semiconductor layer of the corresponding second LED unit 103.

[0075] Specifically, the first electrode layer 108 is located on the second conductive pillar 105, and the first electrode layer 108 is electrically connected to the top surface of the second conductive pillar 105. The side of the first electrode layer 108 away from the second conductive pillar 105 is electrically connected to the first doped semiconductor layer of the second LED unit 103, so that the second LED unit 103 can be located directly above the corresponding first LED unit 102, and each second LED unit 103 can be driven individually by the drive backplate 101.

[0076] Optionally, the first electrode layer 108 is transparent to improve luminous efficiency. The material of the first electrode layer 108 is not limited, for example, indium tin oxide (ITO) or zinc oxide (ZnO).

[0077] In some embodiments, such as Figure 2 , Figures 12 to 17 As shown, the micro LED display structure 100 further includes a bonding layer 109 and a second electrode layer 110. The bonding layer 109 is disposed between the driving backplane 101 and the plurality of first LED units 102. The second electrode layer 110 is disposed between the bonding layer 109 and the corresponding first LED unit 102, and the second electrode layer 110 is used to electrically connect the first contact 1011 to the first doped semiconductor layer of the corresponding first LED unit 102.

[0078] Specifically, a bonding layer 109 is disposed between the driving backplate 101 and the plurality of first LED units 102. The bonding layer 109 enables the vertical stacking and integration of the first LED units 102, improving mechanical strength. A second electrode layer 110 is disposed between the bonding layer 109 and the corresponding first LED unit 102. The second electrode layer 110 electrically connects the first contact 1011 to the first doped semiconductor layer of the corresponding first LED unit 102, allowing each first LED unit 102 to be individually driven by the driving backplate 101. Furthermore, the second electrode layer 110 optimizes current distribution, improving the brightness uniformity of the display structure 100.

[0079] Optionally, the bonding layer 109 may be made of a conductive material, such as a metal.

[0080] Optionally, the second electrode layer 110 is transparent to improve luminous efficiency. The material of the second electrode layer 110 is not limited; for example, it can be indium tin oxide (ITO) or zinc oxide (ZnO).

[0081] Optionally, such as Figure 2 , Figures 12 to 17 As shown, the bonding layer 109 is disposed above the corresponding first contact 1011 at least.

[0082] In some embodiments, such as Figure 2 , Figure 7 , Figures 9 to 17 As shown, the micro LED display structure 100 further includes a third electrode layer 112 and a third conductive post 111. The third electrode layer 112 is disposed on a plurality of first LED units 102 and electrically connected to the second doped semiconductor layer of the plurality of first LED units 102. One end of the third conductive post 111 is electrically connected to the second contact 1012, and the other end of the third conductive post 111 is electrically connected to the third electrode layer 112.

[0083] The third electrode layer 112 is disposed on the plurality of first LED units 102 and electrically connected to the second doped semiconductor layer of the plurality of first LED units 102. One end of the third conductive post 111 is electrically connected to the second contact 1012, and the other end of the third conductive post 111 is electrically connected to the third electrode layer 112, so that the second doped semiconductor layers of the plurality of first LED units 102 can be electrically connected to the second contact 1012 together.

[0084] Specifically, the second doped semiconductor layers of the multiple first LED units 102 are connected to the third conductive pillar 111 through the third electrode layer 112. The third conductive pillar 111 is electrically connected to the second contact 1012 so that the second doped semiconductor layers of the multiple first LED units 102 can be electrically connected to the second contact 1012 together.

[0085] Optionally, such as Figure 2 , Figures 12 to 17 As shown, the third conductive post 111 is at least disposed above the corresponding second contact 1012.

[0086] Optionally, the material of the third conductive post 111 includes, but is not limited to, copper (Cu) or tungsten (W).

[0087] Optionally, the third electrode layer 112 is transparent to improve luminous efficiency. The material of the third electrode layer 112 is not limited; for example, it can be indium tin oxide (ITO) or zinc oxide (ZnO).

[0088] In some embodiments, such as Figure 2 As shown, the micro LED display structure 100 further includes a fourth electrode layer 113 and a fourth conductive post 118. The fourth electrode layer 113 is disposed on the plurality of second LED units 103 and electrically connected to the second doped semiconductor layer of the plurality of second LED units 103. One end of the fourth conductive post 118 is electrically connected to the fourth electrode layer 113, and the other end of the fourth conductive post 118 is electrically connected to the third electrode layer 112.

[0089] A fourth electrode layer 113 is disposed on a plurality of second LED units 103 and electrically connected to the second doped semiconductor layers of the plurality of second LED units 103. One end of a fourth conductive post 118 is electrically connected to the fourth electrode layer 113, and the other end of the fourth conductive post 118 is electrically connected to the third electrode layer 112. The third electrode layer 112 is electrically connected to the third conductive post 111, and the third conductive post 111 is electrically connected to the second contact 1012, so that the second doped semiconductor layers of the plurality of second LED units 103 can be electrically connected to the second contact 1012 together.

[0090] The third electrode layer 112 can also be used to connect the third conductive post 111 and the fourth conductive post 118 in the vertical direction, so that the second doped semiconductor layers of the multiple second LED units 103 are electrically connected to the second contact 1012.

[0091] For example, the second doped semiconductor layers of the plurality of first LED units 102 and the second doped semiconductor layers of the plurality of second LED units 103 can all be connected to the third conductive post 111, so as to be connected to the second contact 1012 through the third conductive post 111, thereby realizing that the second doped semiconductor layers of the plurality of first LED units 102 and the second doped semiconductor layers of the plurality of second LED units 103 are electrically connected to the second contact 1012.

[0092] Optionally, the fourth electrode layer 113 is transparent to improve luminous efficiency. The material of the fourth electrode layer 113 is not limited; for example, it can be indium tin oxide (ITO) or zinc oxide (ZnO).

[0093] Optionally, the material of the fourth conductive post 118 includes, but is not limited to, copper (Cu) or tungsten (W).

[0094] In some embodiments, such as Figures 14 to 17 As shown, the micro LED display structure 100 further includes a first filler layer 106 and a second filler layer 107. The first filler layer 106 is disposed on the driving backplate 101, and at least covers a plurality of first LED units 102 and a plurality of first conductive pillars 104, and at least exposes the top surface of the plurality of first conductive pillars 104. The second filler layer 107 is bonded to the first filler layer 106. The second filler layer 107 is provided with a plurality of second conductive pillars 105. The second LED units 103 are disposed above the second filler layer 107, such that the first LED units 102 and the second LED units 103 stacked above the first LED units 102 are spaced apart. Wherein, when the second filler layer 107 is bonded to the first filler layer 106, the plurality of second conductive pillars 105 are bonded to the plurality of first conductive pillars 104 in a one-to-one correspondence.

[0095] In this embodiment, the flatness of the display structure can be improved by using the first leveling layer 106 and the second leveling layer 107, thereby improving the stability and durability of the display structure 100. Specifically, the first leveling layer 106 is disposed on the driving backplate 101, and covers at least a plurality of first LED units 102 and a plurality of first conductive pillars 104, reducing height differences and improving uniformity. The first leveling layer 106 exposes at least the top surface of a plurality of first conductive pillars 104, facilitating the bonding of the second conductive pillars 105 to the first conductive pillars 104.

[0096] In this embodiment, the second leveling layer 107 is provided with a plurality of second conductive pillars 105. Specifically, the second leveling layer 107 is provided with a plurality of second conductive pillars 105 corresponding one-to-one with a plurality of first conductive pillars 104. When the second leveling layer 107 is bonded to the first leveling layer 106, the plurality of second conductive pillars 105 are bonded one-to-one with the plurality of first conductive pillars 104. That is, by using a hybrid bonding method, the stability and reliability of electrical performance are improved, the brightness of the display structure 100 is increased, stress release is achieved, and bond warping is reduced.

[0097] In this embodiment, the second LED unit 103 is disposed above the second filling layer 107, so that the first LED unit 102 and the second LED unit 103 stacked above the first LED unit 102 are spaced apart, reducing mutual light interference and optimizing heat dissipation.

[0098] Optionally, the material of the first leveling layer 106 includes, but is not limited to, silicon dioxide (SiO2), silicon nitride (SiN), or silicon oxynitride (SiON).

[0099] Optionally, the material of the second leveling layer 107 includes, but is not limited to, silicon dioxide (SiO2), silicon nitride (SiN), or silicon oxynitride (SiON).

[0100] In some embodiments, such as Figure 9 and Figure 10 As shown, the first conductive post 104 includes a first post segment 1041 and a second post segment 1042 connected to each other. The first filler layer 106 includes a first layer 1061 and a second layer 1062. The first layer 1061 is disposed on the drive backplate 101. The first layer 1061 covers at least a plurality of first LED units 102. The first post segment 1041 is formed on the first layer 1061 and is electrically connected to a corresponding first contact 1011. The second layer 1062 is disposed on the first layer 1061. The second post segment 1042 is formed on the second layer 1062. One end of the second post segment 1042 is electrically connected to the corresponding first post segment 1041, and the other end of the second post segment 1042 is electrically connected to the corresponding second conductive post 105.

[0101] Specifically, the first post segment 1041 is disposed on the drive back plate 101, the second post segment 1042 is disposed on the top of the first post segment 1041, and the second conductive post 105 is bonded to the top surface of the second post segment 1042.

[0102] The first layer 1061 covers at least a plurality of first LED units 102. A first pillar segment 1041 of the first conductive pillar 104 is disposed on the first layer 1061. A second pillar segment 1042 of the first conductive pillar 104 is disposed on the second layer 1062. A second filler layer 107 is bonded to the top surface of the second layer 1062.

[0103] Optionally, such as Figure 16 As shown, the micro LED display structure 100 also includes a third leveling layer 117. The third leveling layer 117 is disposed on the second leveling layer 107. The third leveling layer 117 covers at least a plurality of second LED units 103, which can protect the second LED units 103 and improve the flatness of the display structure 100.

[0104] In some embodiments, such as Figure 17 As shown, Figure 17 The 'a' indicates the spacing between the first LED unit 102 and the second LED unit 103 stacked above the first LED unit 102. The spacing (a) between the first LED unit 102 and the second LED unit 103 stacked above the first LED unit 102 is 100 nm to 2 μm.

[0105] In other words, the spacing between the second LED unit 103 and the first LED unit 102 located directly below it is 100nm to 2μm to improve display performance.

[0106] Optionally, the spacing between the first LED unit 102 and the second LED unit 103 stacked above the first LED unit 102 is 100nm, 500nm, 1000nm, 2μm or other values ​​between 100nm and 2μm.

[0107] In some embodiments, combined with Figure 2 and Figure 17 As shown, the first LED unit 102 and the second LED unit 103 stacked above it are coaxially arranged. The first conductive post 104 and the second conductive post 105 are located directly above the corresponding first contact 1011. The projections of the second LED unit 103 and the corresponding first contact 1011 on the drive backplate 101 do not overlap. Figures 1 to 18 As shown, this disclosure also provides a display device 200. The display device 200 includes a miniature light-emitting diode display structure 100 as described in any of the preceding embodiments.

[0108] Combination Figure 2 and Figure 17 As shown, by coaxially arranging the first LED unit 102 and the second LED unit 103 stacked above the first LED unit 102, color mixing is achieved in the vertical space, the light-emitting area of ​​the full-color pixels is reduced, the brightness is improved, higher full-color resolution is obtained, the pixel pitch is reduced, and the lifespan and display effect of the display structure are improved.

[0109] In this embodiment, the display device 200 includes the micro LED display structure 100 as in any of the previous embodiments, and therefore has all the beneficial effects of the micro LED display structure 100 as in any of the previous embodiments, which will not be described in detail here.

[0110] In this embodiment, the micro LED display structure 100 or display device 200 can be applied to augmented reality (AR) display devices, virtual reality (VR) display devices, near-eye display (NED) devices, head-up display (HUD) devices, etc.

[0111] The following describes an exemplary method for fabricating the micro LED display structure 100 to further illustrate this embodiment.

[0112] Step 1: As Figure 3As shown, a first epitaxial wafer 114 is prepared. The first epitaxial wafer 114 includes a first substrate 1141, a first epitaxial structure 1142, a first current spreading layer 1143, and a bonding metal layer 1144, which are sequentially stacked. The material of the first substrate 1141 includes, but is not limited to, silicon, sapphire, or gallium arsenide (GaAs). The first epitaxial structure 1142 is used to form a first LED unit 102. The first current spreading layer 1143 is used to form a second electrode layer 110. The bonding metal layer 1144 is used to connect to the driving backplane 101 and to form a bonding layer 109.

[0113] Step 2: As Figure 4 As shown, the first epitaxial wafer 114 is connected to the drive backplane 101. Specifically, the bonding metal layer 1144 of the first epitaxial wafer 114 is connected to the drive backplane 101. The method of connecting the bonding metal layer 1144 to the drive backplane 101 is not limited; for example, it can be connected by bonding.

[0114] Step 3: As Figure 5 As shown, a first layer 1061 is formed, comprising multiple first LED units 102 and a first leveling layer 106. Specifically, the first substrate 1141 is removed by any method, such as chemical etching or laser lift-off. The first epitaxial structure 1142 is etched to form multiple first LED units 102. The specific method of etching the first epitaxial structure 1142 is not limited, such as mesa etching. The first current spreading layer 1143 is etched to form the second electrode layer 110. The bonding metal layer 1144 is etched to form the bonding layer 109, which is located above the first contact 1011.

[0115] Optionally, a passivation layer may be formed, covering at least the surface of the first LED unit 102, the side surface of the second electrode layer 110, and the side surface of the bonding layer 109 to achieve insulation. The material of the passivation layer is not limited, for example, silicon dioxide. Of course, when the first LED unit 102 is connected to the third electrode layer 112, etc., part of the passivation layer may be etched away to achieve the connection, so that each first LED unit 102 can be driven individually by the drive backplane 101.

[0116] Furthermore, a filler material (e.g., silicon dioxide) is deposited on the drive backplate 101 to form a first layer 1061 of the first filler layer 106, such that the first layer 1061 covers the plurality of first LED units 102. The first layer 1061 can be processed by chemical mechanical polishing to improve surface flatness.

[0117] Step 4: As Figure 6As shown, a first pillar segment 1041 and a third conductive pillar 111 are formed to form the first conductive pillar 104. A first through-hole and a second through-hole are formed in the first layer 1061 of the first filling layer 106 along the vertical direction. The first pillar segment 1041 is formed by filling the first through-hole with material, and is positioned above the first contact 1011. The third conductive pillar 111 is formed by filling the second through-hole with material, and is positioned above the second contact 1012.

[0118] Step 5: As Figure 7 As shown, a third electrode layer 112 is formed. A third via is formed along the vertical direction in the first layer 1061 of the first filling layer 106 to expose all or part of the top surface of the first LED unit 102. An electrode layer is formed on the top surface of the first layer 1061, allowing the electrode layer to fill the third via and cover the top surfaces of the first pillar segment 1041 and the third conductive pillar 111. The electrode layer is etched to form the third electrode layer 112, exposing the top surface of the first pillar segment 1041. At this point, the third electrode layer 112 covers the top surface of the third conductive pillar 111.

[0119] Step 6: As Figure 8 and Figure 9 As shown, a second layer 1062 is formed on the first filler layer 106. A filler material (e.g., silicon dioxide) is deposited on the first layer 1061 to form the second layer 1062, which may cover the top surface of the third electrode layer 112 and the first pillar segment 1041.

[0120] Step 7: As Figure 10 As shown, a second pillar segment 1042 forms the first conductive pillar 104. Specifically, a fourth through-hole is formed along the vertical direction in the second layer 1062 of the first filler layer 106 to expose the top surface of the first pillar segment 1041. The fourth through-hole is filled to form the second pillar segment 1042, so that the first pillar segment 1041 and the second pillar segment 1042 form the first conductive pillar 104.

[0121] Step 8: As Figure 11 As shown, a second epitaxial wafer 115 is prepared. The second epitaxial wafer 115 includes a second substrate 1151, a second epitaxial structure 1152, a second current spreading layer 1153, and a second leveling layer 107, which are sequentially stacked. The material of the second substrate 1151 includes, but is not limited to, silicon or sapphire. The second epitaxial structure 1152 is used to form a second LED unit 103. The second current spreading layer 1153 is used to form a first electrode layer 108. A fifth via is formed in the second leveling layer 107. The fifth via is filled to form a second conductive pillar 105, one end of which is connected to the second current spreading layer 1153.

[0122] Step 9: As Figure 12As shown, the second filling layer 107 is bonded to the second layer 1062 of the first filling layer 106. Figure 12 The dashed line b in the figure is used to indicate the bonding position between the second filling layer 107 and the first filling layer 106. At this bonding position, when the second filling layer 107 is bonded to the second layer 1062 of the first filling layer 106, the end of the second conductive post 105 away from the second current extension layer 1153 is bonded to the second post segment 1042 of the first conductive post 104.

[0123] Step 10: As Figure 13 As shown, the second substrate 1151 is removed. It is understood that the method of removing the second substrate 1151 is not limited. For example, the second substrate 1151 can be removed by chemical etching or laser ablation.

[0124] Step 11: As Figure 14 As shown, a plurality of second LED units 103 are formed. Specifically, the second current spreading layer 1153 is etched to form a plurality of second LED units 103.

[0125] Step 12: As Figure 15 As shown, a first electrode layer 108 is formed. Specifically, the second current spreading layer 1153 is etched to form the first electrode layer 108.

[0126] Step 13: As Figure 16 As shown, a third filler layer 117 is formed. Specifically, a filler material (e.g., silicon dioxide) is deposited on the second filler layer 107 to form the third filler layer 117. The third filler layer 117 may cover the first electrode layer 108 and the plurality of second LED units 103. At this time, the first filler layer 106, the second filler layer 107 and the third filler layer 117 may together constitute the filler layer 116.

[0127] Step 14: As Figure 17 As shown, a fourth conductive pillar 118 is formed. Specifically, a sixth through-hole is formed in the filler layer 116 along the vertical direction. The sixth through-hole exposes a portion of the top surface of the third electrode layer 112, formed in step 5 and located on top of the third conductive pillar 111. The sixth through-hole is filled to form the four conductive pillars 118, meaning that the third electrode layer 112 can be used to connect the third conductive pillar 111 and the fourth conductive pillar 118 in the vertical direction, which helps to electrically connect the second doped semiconductor layers of the plurality of second LED units 103 and the second doped semiconductor layers of the plurality of first LED units 102 to the second contact 1012.

[0128] Step 15: As Figure 2As shown, a fourth electrode layer 113 is formed. Specifically, a seventh via is formed in the filler layer 116 along the vertical direction, the seventh via exposing the top surface of the second LED unit 103. The fourth electrode layer 113 is formed on the top surface of the filler layer 116, wherein the fourth electrode layer 113 can fill the seventh via and cover the top surface of the fourth conductive post 118, so as to electrically connect the second doped semiconductor layers of the plurality of second LED units 103 to the second contact 1012.

[0129] In summary, the fabrication of the miniature light-emitting diode display structure 100 in this example is complete.

[0130] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A miniature light-emitting diode display structure, characterized in that, include: Drive backplane; Multiple first LED units are spaced apart on the driving backplane. Each first LED unit can be driven individually by the driving backplane. Each first LED unit includes a first doped semiconductor layer, a first active layer, and a second doped semiconductor layer. Each first LED unit emits a first color light. Multiple second LED units are stacked one-to-one on multiple first LED units. Each second LED unit can be driven individually by the driving backplane. Each second LED unit includes a first doped semiconductor layer, a second active layer, and a second doped semiconductor layer. The second LED unit emits mixed-color light, which includes a second color light and a third color light. The first color light, the second color light, and the third color light are all different. In this configuration, one of the first LED units and the second LED units stacked on top of the first LED unit constitute a full-color pixel.

2. The micro light-emitting diode display structure according to claim 1, characterized in that, The driving backplate includes a driving circuit having multiple first contacts and at least one second contact, and the micro LED display structure further includes a first conductive post and a second conductive post bonded to the first conductive post. A portion of the first contact is electrically connected to the first doped semiconductor layer of the corresponding first LED unit; A portion of the first contact is electrically connected to the corresponding first conductive post, and the second conductive post bonded to the first conductive post is electrically connected to the first doped semiconductor layer of the corresponding second LED unit; The second doped semiconductor layers of the plurality of first LED units and the second doped semiconductor layers of the plurality of second LED units are electrically connected to the second contact.

3. The micro light-emitting diode display structure according to claim 2, characterized in that, Also includes: A first electrode layer is disposed between the second conductive post and the corresponding second LED unit, for electrically connecting the second conductive post and the first doped semiconductor layer of the corresponding second LED unit.

4. The micro light-emitting diode display structure according to claim 2, characterized in that, Also includes: A bonding layer is disposed between the driving backplate and the plurality of first LED units; The second electrode layer is disposed between the bonding layer and the corresponding first LED unit, and is used to electrically connect the first contact and the first doped semiconductor layer of the corresponding first LED unit.

5. The micro light-emitting diode display structure according to claim 2, characterized in that, Also includes: A third electrode layer is disposed on a plurality of first LED units and electrically connected to the second doped semiconductor layer of the plurality of first LED units; The third conductive post is electrically connected at one end to the second contact and at the other end to the third electrode layer.

6. The micro light-emitting diode display structure according to claim 5, characterized in that, Also includes: A fourth electrode layer is disposed on a plurality of second LED units and electrically connected to the second doped semiconductor layer of the plurality of second LED units; The fourth conductive post is electrically connected at one end to the fourth electrode layer and at the other end to the third electrode layer.

7. The micro light-emitting diode display structure according to claim 2, characterized in that, Also includes: A first filler layer is disposed on the drive back plate, covering at least a plurality of the first LED units and a plurality of the first conductive pillars, and exposing at least the top surface of a plurality of the first conductive pillars; The second filler layer is bonded to the first filler layer, and the second filler layer is provided with a plurality of second conductive pillars; The second LED unit is disposed above the second filler layer, such that the first LED unit and the second LED unit stacked above the first LED unit are spaced apart; Specifically, when the second filler layer is bonded to the first filler layer, a plurality of second conductive pillars are bonded to a plurality of first conductive pillars in a one-to-one correspondence.

8. The micro light-emitting diode display structure according to claim 7, characterized in that, The first conductive pillar includes a first pillar segment and a second pillar segment connected to each other, and the first filler layer includes: The first layer is disposed on the drive back plate and covers at least a plurality of the first LED units. The first column segment is formed in the first layer and is electrically connected to the corresponding first contact. The second layer is disposed on the first layer, and the second column segment is formed in the second layer. One end of the second column segment is electrically connected to the corresponding first column segment, and the other end is electrically connected to the corresponding second conductive column.

9. The micro light-emitting diode display structure according to claim 2, characterized in that, The first LED unit and the second LED unit stacked above the first LED unit are coaxially arranged; The first conductive post and the second conductive post are located directly above the corresponding first contact point; The projection of the second LED unit and the corresponding first contact on the drive backplate do not overlap.

10. The micro light-emitting diode display structure according to claim 1, characterized in that, The spacing between the first LED unit and the second LED unit stacked above the first LED unit is 100 nm to 2 μm.

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