Light-emitting device, method for manufacturing the same, and display panel

Abstract

The present disclosure provides a light emitting device, a preparation method thereof and a display panel, and belongs to the technical field of optoelectronic manufacturing. The light emitting device comprises a passivation layer, an electrode, a connection trace, a protective layer and a plurality of single-color light emitting structures. The plurality of single-color light emitting structures are arranged at intervals. The passivation layer is located on each single-color light emitting structure and covers each single-color light emitting structure. The connection trace is located on the surface of the passivation layer away from the single-color light emitting structures and is electrically connected to the single-color light emitting structures through a via of the passivation layer. The electrode is located on the surface of the passivation layer away from the single-color light emitting structures and is connected to the connection trace. The protective layer is located on the surface of the passivation layer away from the single-color light emitting structures. The surface of the protective layer has a groove exposing the electrode. The present disclosure can improve the problem of easy deviation of soldering of the light emitting device in the mounting process and improve the reliability of the light emitting device.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light-emitting device, its fabrication method, and a display panel. Background Technology

[0002] Three-color light-emitting devices are electronic components that use the three-color principle to make light-emitting diodes emit different colors of light. These devices are self-emissive and feature high brightness, high contrast, high responsiveness, and low power consumption.

[0003] In related technologies, light-emitting devices typically include a substrate, electrodes, pads, a passivation layer, a protective layer, and multiple monochromatic light-emitting structures spaced apart on the substrate. The passivation layer covers the substrate and all monochromatic light-emitting structures; electrodes are disposed on the surface of the passivation layer and electrically connected to the monochromatic light-emitting structures through vias in the passivation layer; the protective layer covers the passivation layer and electrodes; pads are disposed on the surface of the protective layer and electrically interconnected with the electrodes below through vias in the protective layer.

[0004] However, after the solder pads are fabricated, their surface often protrudes above the surrounding protective layer. During actual mounting, this height difference leads to uneven solder paste application and distribution on the pads. Consequently, during the reflow soldering process, the asymmetrical wetting tension of the solder can cause the light-emitting devices to shift during soldering, affecting reliability. Summary of the Invention

[0005] This disclosure provides a light-emitting device, its fabrication method, and a display panel, which can improve the problem of easy misalignment during the soldering process of the light-emitting device and enhance its reliability. The technical solution is as follows: This disclosure provides a light-emitting device, comprising: a passivation layer, electrodes, interconnecting traces, a protective layer, and a plurality of monochromatic light-emitting structures; the plurality of monochromatic light-emitting structures are arranged at intervals, the passivation layer is located on each monochromatic light-emitting structure and covers each monochromatic light-emitting structure, the interconnecting traces are located on the surface of the passivation layer away from the monochromatic light-emitting structure, and are electrically connected to the monochromatic light-emitting structure through vias in the passivation layer; the electrodes are located on the surface of the passivation layer away from the monochromatic light-emitting structure and are connected to the interconnecting traces, the protective layer is located on the surface of the passivation layer away from the monochromatic light-emitting structure, and the surface of the protective layer has grooves exposing the electrodes.

[0006] In another implementation of the present disclosure, the orthographic projection of the electrode on the surface of the passivation layer lies within the orthographic projection of the groove on the surface of the passivation layer.

[0007] In another implementation of the present disclosure, the light-emitting device further includes a pad located within the groove and on the surface of the electrode away from the monochromatic light-emitting structure.

[0008] In another implementation of the present disclosure, the top surface of the pad away from the monochromatic light-emitting structure is higher than the surface of the protective layer away from the monochromatic light-emitting structure; or, the top surface of the pad away from the monochromatic light-emitting structure is flush with the surface of the protective layer away from the monochromatic light-emitting structure.

[0009] In another implementation of this disclosure, the distance between the top surface of the pad and the surface of the protective layer away from the monochromatic light-emitting structure is less than 0.5 μm.

[0010] In another implementation of this disclosure, the light-emitting device includes three monochromatic light-emitting structures; the electrode includes a first conductive block, a second conductive block, a third conductive block, and a fourth conductive block, wherein the first conductive block, the second conductive block, the third conductive block, and the fourth conductive block are arranged circumferentially at intervals along the peripheral edge of the passivation layer; the first conductive block, the second conductive block, and the third conductive block are respectively connected to the three monochromatic light-emitting structures through corresponding connection traces, and the fourth conductive block is simultaneously connected to the three monochromatic light-emitting structures through corresponding connection traces.

[0011] In another implementation of this disclosure, the orthographic projection of the protective layer onto the surface of the passivation layer away from the monochromatic light-emitting structure is cross-shaped, and the first conductive block, the second conductive block, the third conductive block, and the fourth conductive block are respectively located in the four corner regions of the cross-shaped protective layer.

[0012] In another implementation of the embodiments of this disclosure, the thickness of the protective layer is 1 μm to 10 μm.

[0013] This disclosure provides a method for fabricating a light-emitting device, the method comprising: transferring a plurality of monochromatic light-emitting structures onto a substrate, such that the plurality of monochromatic light-emitting structures are arranged at intervals; forming a passivation layer on the substrate covering each of the monochromatic light-emitting structures; forming connection traces and electrodes on the surface of the passivation layer away from the monochromatic light-emitting structures, wherein the connection traces are electrically connected to the monochromatic light-emitting structures through vias in the passivation layer, and the electrodes are connected to the connection traces; and forming a protective layer on the surface of the passivation layer away from the monochromatic light-emitting structures, wherein the surface of the protective layer has grooves exposing the electrodes.

[0014] This disclosure provides a display panel, which includes a plurality of light-emitting devices, a driving integrated circuit, and a circuit board as described above, wherein the plurality of light-emitting devices and the driving integrated circuit are all located on the circuit board.

[0015] The beneficial effects of the technical solutions provided in this disclosure include at least the following: The light-emitting device provided in this disclosure has a groove on the surface of the protective layer to expose the electrode, and the electrode is directly disposed in the groove. This design makes the surface of the electrode slightly lower than the surface of the protective layer, thereby reducing the step and height difference caused by the solder pad being higher than the protective layer in related technologies, and ensuring that the solder paste is coated uniformly on the electrode surface.

[0016] Meanwhile, since the electrode is located at the bottom of the groove, the groove wall can act as a limiting and blocking structure. During the solder paste coating process, the groove wall effectively restricts the flow range of the solder paste, preventing it from flowing or overflowing during coating. This ensures that the solder paste is precisely and firmly confined within the preset soldering area, further improving the uniformity and positional accuracy of the solder paste coating. Thanks to the limiting effect of the groove structure on the solder paste, combined with the coplanar design of the electrode and protective layer, the wetting tension of the solder becomes symmetrical and stable during reflow soldering, thereby preventing the light-emitting device from shifting due to uneven tension and improving the reliability of the soldering.

[0017] Furthermore, this improved solution also uses the electrode as a welding electrode. In related technologies, it is usually necessary to fabricate the lower electrode, the upper protective layer, and independent pad structures separately, which is a rather cumbersome process. However, the embodiment of this disclosure eliminates the step of fabricating independent pads on the surface of the protective layer. The electrode not only performs the function of electrical connection but also directly takes into account the welding and butt joint function. This simplifies the fabrication method and process of the light-emitting device and can effectively reduce production costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a top view of a light-emitting device provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure; Figure 3 This is a schematic diagram of another light-emitting device provided in an embodiment of this disclosure; Figure 4This is a flowchart of a method for fabricating a light-emitting device according to an embodiment of this disclosure.

[0020] The markings in the diagram are explained as follows: 10. Substrate; 11. Supporting layer; 21. Passivation layer; 22. Protective layer; 220. Groove; 30. Electrode; 31. First conductive block; 32. Second conductive block; 33. Third conductive block; 34. Fourth conductive block; 40. Connect and route the cables; 50. Monochromatic light-emitting structure; 60. Solder pads. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0022] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0023] Figure 1 This is a top view of a light-emitting device provided in an embodiment of this disclosure. Figure 2 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this disclosure. Figure 1 , 2 As shown, the light-emitting device includes: a passivation layer 21, an electrode 30, a connection trace 40, a protective layer 22, and multiple monochromatic light-emitting structures 50.

[0024] like Figure 2As shown, multiple monochromatic light-emitting structures 50 are arranged at intervals. A passivation layer 21 is located on each monochromatic light-emitting structure 50 and covers each monochromatic light-emitting structure 50. A connection trace 40 is located on the surface of the passivation layer 21 away from the monochromatic light-emitting structure 50, and the connection trace 40 is electrically connected to the monochromatic light-emitting structure 50 through the via of the passivation layer 21.

[0025] like Figure 1 , 2 As shown, electrode 30 is located on the surface of passivation layer 21 away from monochromatic light-emitting structure 50, and electrode 30 is connected to connection trace 40. Protective layer 22 is located on the surface of passivation layer 21 away from monochromatic light-emitting structure 50, and the surface of protective layer 22 has a groove 220 exposing electrode 30.

[0026] The light-emitting device provided in this embodiment has a groove 220 exposed on the surface of the protective layer 22, and the electrode 30 is directly disposed in the groove 220. This design makes the surface of the electrode 30 slightly lower than the surface of the protective layer 22, thereby reducing the step and height difference caused by the solder pad 60 being higher than the protective layer 22 in the related art, and making the coating of solder paste on the surface of the electrode 30 uniform.

[0027] Meanwhile, since electrode 30 is located at the bottom of groove 220, the groove wall of groove 220 can act as a limiting and blocking structure. During the solder paste coating process, the groove wall effectively restricts the flow range of the solder paste, preventing it from flowing or overflowing during coating. This ensures that the solder paste is precisely and firmly confined within the preset soldering area, further improving the uniformity and positional accuracy of the solder paste coating. Thanks to the limiting effect of the groove 220 structure on the solder paste, combined with the coplanar design of electrode 30 and protective layer 22, the wetting tension of the solder becomes symmetrical and stable during reflow soldering, thereby preventing the light-emitting device from shifting due to uneven tension and improving soldering reliability.

[0028] Furthermore, this improved solution also uses electrode 30 as a welding electrode 30. In related technologies, it is usually necessary to fabricate the lower electrode 30, the upper protective layer 22, and independent solder pads 60 structures separately, which is a relatively cumbersome process. However, the embodiment of this disclosure eliminates the step of additionally fabricating independent solder pads 60 on the surface of the protective layer 22. Electrode 30 not only performs the function of electrical connection but also directly takes on the role of welding and butt joint. This simplifies the fabrication method and process of the light-emitting device and can effectively reduce production costs.

[0029] Optionally, such as Figure 1 , 2 As shown, the orthographic projection of electrode 30 on the surface of passivation layer 21 lies within the orthographic projection of groove 220 on the surface of passivation layer 21.

[0030] In the mounting process of light-emitting devices, the height difference between the traditional pad 60 and the surrounding protective layer 22 can lead to uneven solder paste application, which in turn causes soldering misalignment during reflow soldering due to asymmetrical wetting tension. By completely placing the electrode 30 within the groove 220 of the protective layer 22, the groove wall of the groove 220 acts as a natural limiting and blocking structure, effectively preventing solder paste from flowing or overflowing during application and ensuring that the solder paste is precisely and stably confined within the soldering area. This makes the solder wetting tension symmetrical and stable during reflow soldering, thereby preventing device misalignment and significantly improving soldering reliability.

[0031] Furthermore, under different operating conditions of the device, the electrode 30 often faces volume changes due to thermal expansion or electrochemical reactions. Placing the electrode 30 in the groove 220 and maintaining a certain peripheral gap between the outer periphery of the electrode 30 and the groove 220 allows the electrode 30 to expand and move slightly, thereby effectively buffering thermal stress or deformation stress, preventing electrode 30 failure, and extending its service life.

[0032] Optionally, the electrode 30 may extend outward from the connection point with the connecting trace 40 as the contact part, with multiple strip-shaped structures extending outward. Each strip-shaped structure may then have multiple linear, semi-circular, or elliptical extensions symmetrically arranged at its end. This creates a snowflake-like pattern on the electrode 30, and the entire orthographic projection of the electrode 30 is completely within the groove 220.

[0033] In the above implementation, the use of a bifurcated electrode 30 can improve the uniformity of current spread and avoid the problem of local heating caused by current accumulation in the center of the electrode 30. In addition, the extended part of the electrode 30 can fill more areas in the groove 220, reduce the blank area in the groove 220 not covered by the electrode 30, reduce the free flow space of Sn paste in the groove 220, and physically limit the flow range of Sn paste. Even if the amount of Sn paste applied is slightly excessive, it will be confined in the gap of the extended part and will not overflow onto the surface of the protective layer 22.

[0034] Figure 3 This is a schematic diagram of another light-emitting device provided in an embodiment of this disclosure. For example... Figure 3 As shown, the light-emitting device also includes a pad 60, which is located within the groove 220 and on the surface of the electrode 30 away from the monochromatic light-emitting structure 50.

[0035] If electrode 30 is directly used as the soldering surface and is positioned below the upper surface of passivation layer 21, when the solder paste coating position on the circuit board shifts, the side of the light-emitting device will contact the molten solder paste first and generate wetting force. Since electrode 30 is in a low position, this asymmetrical wetting tension cannot be constrained by the upper surface of the light-emitting device, and it is very easy to pull the entire light-emitting device during reflow soldering, resulting in die skewing.

[0036] This embodiment of the invention elevates the soldering interface by setting the solder pad 60, compensating for the height difference caused by the electrode 30 being lower than the upper surface of the passivation layer 21, making the position of the soldering surface closer to or even higher than the light-emitting device body. Combined with the blocking effect of the groove wall 220, the solder pad 60 precisely limits the soldering area inside the groove 220. Even if the solder paste position is slightly off, the groove wall can prevent excessive solder paste flow, ensuring relatively balanced stress on the soldering interface.

[0037] Optionally, the top surface of the pad 60 away from the monochromatic light-emitting structure 50 is higher than the surface of the protective layer 22 away from the monochromatic light-emitting structure 50.

[0038] For example, the distance between the top surface of the pad 60 and the surface of the protective layer 22 away from the monochromatic light-emitting structure 50 is less than 0.5 μm.

[0039] If the pad 60 is lower than the surrounding structure, it is easy for the surrounding structure to support it during bonding, causing the pad 60 to fail to make effective contact with the circuit board and resulting in a cold solder joint. If the pad 60 is higher than the surface of the protective layer 22, it can ensure that the pad 60 is the first to contact and be pressed with the solder paste or solder on the circuit board at the moment of bonding, thus ensuring sufficient conductivity and tight bonding at the soldering interface and avoiding connection failure caused by insufficient height.

[0040] Optionally, the top surface of the pad 60 away from the monochromatic light-emitting structure 50 is flush with the surface of the protective layer 22 away from the monochromatic light-emitting structure 50.

[0041] During reflow soldering, if the solder paste position shifts and causes one side of the solder to wet the pad 60 first, since the pad 60 is flush with the surrounding protective layer 22, the molten solder paste will be physically blocked and reacted by the surface of the flush protective layer 22 when it wets the edge of the pad 60. This forces the solder tension to be evenly distributed on the entire pad 60, avoiding unilateral sinking or deflection, and fundamentally eliminating die skewing.

[0042] Optionally, such as Figure 2 , 3 As shown, the light-emitting device includes three monochromatic light-emitting structures 50.

[0043] In this embodiment of the disclosure, the three monochromatic light-emitting structures 50 may include a red epitaxial layer, a green epitaxial layer, and a blue epitaxial layer.

[0044] The red epitaxial layer comprises a first p-type layer, a first luminescent layer, and a first n-type layer stacked sequentially.

[0045] In the red-light epitaxial layer, the first p-type layer includes a p-type AlInP layer.

[0046] The first luminescent layer comprises alternating layers of AlGaInP quantum wells and AlGaInP quantum barriers, wherein the Al content in the AlGaInP quantum well layers and AlGaInP quantum barrier layers differs. The first luminescent layer may comprise 3 to 8 alternating stacked cycles of AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0047] The first n-type layer includes an n-type AlGaInP current-spreading layer.

[0048] In this embodiment of the disclosure, the green epitaxial layer includes a second p-type layer, a second luminescent layer, and a second n-type layer stacked sequentially.

[0049] In the green epitaxial layer, the second p-type layer includes a p-type GaN layer.

[0050] The second light-emitting layer comprises alternating InGaN quantum well layers and GaN quantum barrier layers. The second light-emitting layer may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0051] The second n-type layer includes an n-type GaN layer.

[0052] In this embodiment of the disclosure, the blue light epitaxial layer includes a third p-type layer, a third light-emitting layer, and a third n-type layer stacked sequentially.

[0053] In the blue light epitaxial layer, the third p-type layer includes a p-type GaN layer.

[0054] The third light-emitting layer may include alternating InGaN quantum well layers and GaN quantum barrier layers. The third light-emitting layer may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0055] The third n-type layer includes an n-type GaN layer.

[0056] Optionally, the thickness of the monochromatic light-emitting structure 50 is 2 μm to 10 μm.

[0057] For example, the thickness of the red epitaxial layer is 5 μm, the thickness of the green epitaxial layer is 8 μm, and the thickness of the blue epitaxial layer is 6 μm.

[0058] Optionally, each monochromatic light-emitting structure 50 further includes a positive electrode and a negative electrode. The positive electrode of the monochromatic light-emitting structure 50 is electrically connected to the p-type layer of the epitaxial layer, and the negative electrode of the monochromatic light-emitting structure 50 is connected to the n-type layer of the epitaxial layer.

[0059] like Figure 1 , 2As shown, the electrode 30 includes a first conductive block 31, a second conductive block 32, a third conductive block 33, and a fourth conductive block 34, which are arranged circumferentially along the peripheral edge of the passivation layer 21.

[0060] The four conductive blocks are arranged circumferentially along the periphery of the passivation layer 21, forming a surrounding current distribution network. This arrangement avoids the problem of uneven current distribution caused by the concentration of conductive blocks in local areas of the chip.

[0061] like Figure 1 , 2 As shown, the first conductive block 31, the second conductive block 32 and the third conductive block 33 are connected to the three monochromatic light-emitting structures 50 through corresponding connection lines 40, and the fourth conductive block 34 is connected to the three monochromatic light-emitting structures 50 through corresponding connection lines 40.

[0062] For example, the first conductive block 31, the second conductive block 32 and the third conductive block 33 are respectively connected to the positive electrode of the three monochromatic light-emitting structures 50 through corresponding connection lines 40.

[0063] For example, the fourth conductive block 34 is connected to the negative electrode of the three monochromatic light-emitting structures 50 through the corresponding connection trace 40.

[0064] In this embodiment, the first, second, and third conductive blocks are connected one-to-one with the three monochromatic light-emitting structures 50 via dedicated connection traces 40, thus achieving independent current control of the monochromatic light-emitting units. In applications such as Mini / Micro LED, the three monochromatic light-emitting structures 50 typically correspond to red, green, and blue primary color units. Independent conductive blocks can avoid current crosstalk between different color units, ensuring that each monochromatic structure receives a precisely matched driving current during driving, thereby guaranteeing the stability of optical performance such as color gamut coverage and color reproduction. At the same time, the independent connection traces 40 shorten the current transmission path, reduce the contact resistance between a single conductive block and the monochromatic structure, and reduce localized heating problems caused by current congestion.

[0065] Furthermore, the fourth conductive block 34 is connected to three monochromatic light-emitting structures 50 simultaneously via a single connection trace 40, and can typically serve as a common electrode 30. This electrode arrangement reduces the number of electrodes 30 and the complexity of the connection traces 40.

[0066] Optionally, such as Figure 2 As shown, the orthographic projection of the protective layer 22 onto the surface of the passivation layer 21 away from the monochromatic light-emitting structure 50 is cross-shaped, and the first conductive block 31, the second conductive block 32, the third conductive block 33 and the fourth conductive block 34 are respectively located in the four corner regions of the cross-shaped protective layer 22.

[0067] In the above implementation, the four corner regions of the cross-shaped protective layer 22 correspond precisely to the arrangement positions of the first, second, third, and fourth conductive blocks. This layout disperses the conductive blocks in the four diagonal regions around the light-emitting device, forming a surrounding current transmission network. For the three monochromatic light-emitting structures 50, the first, second, and third conductive blocks are connected to their respective monochromatic structures via dedicated connection traces 40, while the fourth conductive block 34 serves as the common electrode 30, connecting all three structures simultaneously. The gaps in the cross-shaped protective layer 22 provide space for the connection traces 40, preventing trace crossing and overlap. This dispersed conductive block layout effectively widens the current diffusion range in the active layer of the monochromatic light-emitting structure 50, reducing current congestion. The cross-shaped layout combined with the dispersed conductive blocks reduces the risk of localized overheating and extends the lifespan of the light-emitting device.

[0068] Meanwhile, the four corner areas of the cross-shaped protective layer 22 correspond precisely to four independent groove areas 220, and the groove walls of the grooves 220 can physically limit the solder paste on the conductive blocks. When the solder paste application position on the circuit board is slightly off, the corner grooves 220 of the cross-shaped layout can independently limit the solder paste range of each pad 60, avoiding solder paste bridging between different conductive blocks.

[0069] Optionally, the thickness of the protective layer 22 is from 1 μm to 10 μm.

[0070] By controlling the thickness of the protective layer 22 within the range of 1μm to 10μm, it effectively blocks the intrusion of corrosive gases such as moisture and sulfides, preventing corrosion of the electrode 30 or burns to the light-emitting area. It also protects the light-emitting unit and connecting traces 40 from external impacts and moisture, reducing the risk of leakage and extending the lifespan of the light-emitting device in harsh environments. Simultaneously, it avoids light absorption loss and enhanced total internal reflection caused by an excessively thick protective layer 22, reducing the decrease in light extraction efficiency.

[0071] For example, the thickness of the protective layer 22 is 2 μm.

[0072] Optionally, such as Figure 1 As shown, the light-emitting device may also include a substrate 10 and a carrier layer 11, with the carrier layer 11 located on the substrate 10 and multiple monochromatic light-emitting devices arranged at intervals on the carrier layer 11.

[0073] The substrate 10 can be a sapphire substrate 10 or a glass substrate 10.

[0074] Optionally, the carrier layer 11 may be at least one of a silicon oxide layer, a silicon nitride layer, and a titanium oxide layer. The thickness of the carrier layer 11 may be from 3 μm to 30 μm.

[0075] For example, the thickness of the carrier layer 11 can be 10 μm.

[0076] Figure 4 This is a flowchart illustrating a method for fabricating a light-emitting device according to an embodiment of this disclosure. For example... Figure 4 As shown, the preparation method includes: Step S11: Transfer multiple monochromatic light-emitting structures 50 onto the substrate 10, so that the multiple monochromatic light-emitting structures 50 are arranged at intervals.

[0077] Step S12: Form a passivation layer 21 on the substrate 10 covering each monochromatic light-emitting structure 50.

[0078] Step S13: Form the connection trace 40 and the electrode 30 on the surface of the passivation layer 21 away from the monochromatic light-emitting structure 50.

[0079] The connecting trace 40 is electrically connected to the monochromatic light-emitting structure 50 through the via of the passivation layer 21, and the electrode 30 is connected to the connecting trace 40.

[0080] Step S14: A protective layer 22 is formed on the surface of the passivation layer 21 away from the monochromatic light-emitting structure 50. The surface of the protective layer 22 has a groove 220 that exposes the electrode 30.

[0081] The light-emitting device fabricated by this method has a groove 220 on the surface of the protective layer 22 exposing the electrode 30, and the electrode 30 is directly placed in the groove 220. This design makes the surface of the electrode 30 slightly lower than the surface of the protective layer 22, thereby reducing the step and height difference caused by the solder pad 60 being higher than the protective layer 22 in related technologies, and ensuring that the solder paste coating on the surface of the electrode 30 remains uniform.

[0082] Meanwhile, since electrode 30 is located at the bottom of groove 220, the groove wall of groove 220 can act as a limiting and blocking structure. During the solder paste coating process, the groove wall effectively restricts the flow range of the solder paste, preventing it from flowing or overflowing during coating. This ensures that the solder paste is precisely and firmly confined within the preset soldering area, further improving the uniformity and positional accuracy of the solder paste coating. Thanks to the limiting effect of the groove 220 structure on the solder paste, combined with the coplanar design of electrode 30 and protective layer 22, the wetting tension of the solder becomes symmetrical and stable during reflow soldering, thereby preventing the light-emitting device from shifting due to uneven tension and improving soldering reliability.

[0083] Furthermore, this improved solution also uses electrode 30 as a welding electrode 30. In related technologies, it is usually necessary to fabricate the lower electrode 30, the upper protective layer 22, and independent solder pads 60 structures separately, which is a relatively cumbersome process. However, the embodiment of this disclosure eliminates the step of additionally fabricating independent solder pads 60 on the surface of the protective layer 22. Electrode 30 not only performs the function of electrical connection but also directly takes on the role of welding and butt joint. This simplifies the fabrication method and process of the light-emitting device and can effectively reduce production costs.

[0084] The multiple monochromatic light-emitting structures 50 in step S11 may include a red epitaxial layer, a green epitaxial layer, and a blue epitaxial layer.

[0085] The red epitaxial layer comprises a first p-type layer, a first luminescent layer, and a first n-type layer stacked sequentially.

[0086] In the red-light epitaxial layer, the first p-type layer includes a p-type AlInP layer.

[0087] The first luminescent layer comprises alternating layers of AlGaInP quantum wells and AlGaInP quantum barriers, wherein the Al content in the AlGaInP quantum well layers and AlGaInP quantum barrier layers differs. The first luminescent layer may comprise 3 to 8 alternating stacked cycles of AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0088] The first n-type layer includes an n-type AlGaInP current-spreading layer.

[0089] In this embodiment of the disclosure, the green epitaxial layer includes a second p-type layer, a second luminescent layer, and a second n-type layer stacked sequentially.

[0090] In the green epitaxial layer, the second p-type layer includes a p-type GaN layer.

[0091] The second light-emitting layer comprises alternating InGaN quantum well layers and GaN quantum barrier layers. The second light-emitting layer may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0092] The second n-type layer includes an n-type GaN layer.

[0093] In this embodiment of the disclosure, the blue light epitaxial layer includes a third p-type layer, a third light-emitting layer, and a third n-type layer stacked sequentially.

[0094] In the blue light epitaxial layer, the third p-type layer includes a p-type GaN layer.

[0095] The third light-emitting layer may include alternating InGaN quantum well layers and GaN quantum barrier layers. The third light-emitting layer may include 3 to 8 alternating stacked InGaN quantum well layers and GaN quantum barrier layers.

[0096] The third n-type layer includes an n-type GaN layer.

[0097] Optionally, the thickness of the monochromatic light-emitting structure 50 is 2 μm to 10 μm.

[0098] For example, the thickness of the red epitaxial layer is 5 μm, the thickness of the green epitaxial layer is 8 μm, and the thickness of the blue epitaxial layer is 6 μm.

[0099] Optionally, each monochromatic light-emitting structure 50 further includes a positive electrode and a negative electrode. The positive electrode of the monochromatic light-emitting structure 50 is electrically connected to the p-type layer of the epitaxial layer, and the negative electrode of the monochromatic light-emitting structure 50 is connected to the n-type layer of the epitaxial layer.

[0100] Step S11 may include: selecting red, green and blue LED chips as a single-color light-emitting structure 50, and the chip size can be controlled below 50μm to adapt to the requirements of Micro-LED micro-pitch display.

[0101] Through mass transfer processes such as flexible stamp picking, releasing, and laser transfer, the three types of chips are precisely transferred onto the substrate 10 according to a fixed pixel cycle, ensuring that the red, green, and blue chips are arranged at intervals on the substrate 10 to form the smallest light-emitting pixel unit.

[0102] Step S12 may include: First, a passivation layer 21 is uniformly coated or deposited on the substrate 10 and the surface of all monochromatic light-emitting structures 50 by means of spin coating, plasma-enhanced chemical vapor deposition (PECVD), etc.

[0103] For example, the passivation layer 21 can be made of dielectric materials such as silicon oxide, silicon nitride, or polyimide.

[0104] For example, the thickness of the passivation layer 21 is controlled between 1 μm and 10 μm, which can effectively block the intrusion of corrosive gases such as water vapor and sulfides, avoid corrosion of the electrode 30 or burns of the light-emitting area, protect the light-emitting unit and connecting wires from external collisions and moisture, reduce the risk of PN junction leakage, and is compatible with conventional deposition processes such as spin coating and CVD, with controllable density, taking into account both manufacturing yield and economic benefits.

[0105] Next, after the passivation layer 21 is formed, a photolithography process is used to define the pattern and open vias at the positive and negative connection positions of the corresponding red, green, and blue chips. The via size must match the line width of the subsequent connection trace 40 to ensure the smoothness of electrical connection and the reliability of insulation.

[0106] Step S13 may include: First, defining a patterned area connecting the wiring 40 and the electrode 30 on the surface of the passivation layer 21 by photolithography; then, sequentially depositing an adhesion layer (such as titanium or chromium) and a conductive layer (such as aluminum, copper, silver, or alloy material) by electron beam evaporation or magnetron sputtering; and finally forming the final pattern by a lift-off process or an etching process.

[0107] The connecting trace 40 forms an ohmic contact with the positive and negative electrodes of the corresponding monochromatic light-emitting structure 50 through the vias of the passivation layer 21 to achieve electrical signal transmission. The electrode 30 is divided into a first, second, and third conductive block 33 and a fourth conductive block 34, which correspond to the independent connection of the red, green, and blue chips and the connection of the three-color common terminal, respectively. The four conductive blocks are arranged circumferentially around the periphery of the passivation layer 21, and the size is enlarged at the four corners of the three-color die unit, with a single side size greater than 50μm. This reduces the alignment difficulty of subsequent mass transfer and welding, reduces the current congestion effect, and avoids reliability problems such as burns to the transparent conductive layer and metal migration of the electrode 30 caused by local heating.

[0108] Step S14 may include: selecting silicon oxide, titanium oxide and silicon nitride as materials for the protective layer 22, forming a cross-shaped protective layer 22 structure in the central region of the four corner conductive blocks through photolithography, and controlling the overall thickness of the protective layer 22 to be between 1 μm and 10 μm.

[0109] The four corner areas of the cross-shaped layout correspond precisely to the arrangement positions of the four conductive blocks, and the central gap area provides space for the connection traces 40, avoiding trace crossing and overlap. Grooves 220 are formed in the protective layer 22 at the positions corresponding to the four conductive blocks, ensuring that the electrodes 30 are completely located within the grooves 220. The orthographic projection of the electrodes 30 on the surface of the passivation layer 21 lies within the orthographic projection of the grooves 220. The groove walls of the grooves 220 serve as physical limiting structures for solder paste application, preventing solder flow during reflow soldering, preventing the light-emitting devices from shifting during soldering, and improving the bonding strength and long-term stability after mass transfer.

[0110] This disclosure provides a display panel that includes a plurality of light-emitting devices, a driver integrated circuit (IC), and a circuit board as described above, wherein the plurality of light-emitting devices and the driver IC are all located on the circuit board.

[0111] For example, multiple light-emitting device arrays are arranged on a circuit board.

[0112] The driver IC is located on the circuit board and electrically connected via drive traces on the circuit board. The solder pads of multiple light-emitting devices are also electrically connected to the drive traces on the circuit board. In this way, the driver IC can control each light-emitting device through the drive traces.

[0113] The above is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A light-emitting device, characterized in that, The light-emitting device includes: a passivation layer (21), an electrode (30), a connection trace (40), a protective layer (22), and multiple monochromatic light-emitting structures (50). Multiple monochromatic light-emitting structures (50) are arranged at intervals. The passivation layer (21) is located on each monochromatic light-emitting structure (50) and covers each monochromatic light-emitting structure (50). The connection trace (40) is located on the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50) and is electrically connected to the monochromatic light-emitting structure (50) through the via of the passivation layer (21). The electrode (30) is located on the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50) and is connected to the connection trace (40). The protective layer (22) is located on the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50). The surface of the protective layer (22) has a groove (220) exposing the electrode (30).

2. The light-emitting device according to claim 1, characterized in that, The orthographic projection of the electrode (30) on the surface of the passivation layer (21) lies within the orthographic projection of the groove (220) on the surface of the passivation layer (21).

3. The light-emitting device according to claim 2, characterized in that, The light-emitting device also includes a pad (60) located within the groove (220) and on the surface of the electrode (30) away from the monochromatic light-emitting structure (50).

4. The light-emitting device according to claim 3, characterized in that, The top surface of the pad (60) away from the monochromatic light-emitting structure (50) is higher than the surface of the protective layer (22) away from the monochromatic light-emitting structure (50); or, The top surface of the pad (60) away from the monochromatic light-emitting structure (50) is flush with the surface of the protective layer (22) away from the monochromatic light-emitting structure (50).

5. The light-emitting device according to claim 4, characterized in that, The distance between the top surface of the pad (60) and the surface of the protective layer (22) away from the monochromatic light-emitting structure (50) is less than 0.5 μm.

6. The light-emitting device according to any one of claims 1 to 5, characterized in that, The light-emitting device includes three monochromatic light-emitting structures (50); The electrode (30) includes: a first conductive block (31), a second conductive block (32), a third conductive block (33) and a fourth conductive block (34), wherein the first conductive block (31), the second conductive block (32), the third conductive block (33) and the fourth conductive block (34) are arranged circumferentially at intervals along the peripheral edge of the passivation layer (21); The first conductive block (31), the second conductive block (32) and the third conductive block (33) are respectively connected to the three monochromatic light-emitting structures (50) through the corresponding connection lines (40), and the fourth conductive block (34) is simultaneously connected to the three monochromatic light-emitting structures (50) through the corresponding connection lines (40).

7. The light-emitting device according to claim 6, characterized in that, The protective layer (22) is cross-shaped when projected onto the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50). The first conductive block (31), the second conductive block (32), the third conductive block (33), and the fourth conductive block (34) are located in the four corner regions of the cross-shaped protective layer (22).

8. The light-emitting device according to any one of claims 1 to 5, characterized in that, The thickness of the protective layer (22) is 1 μm to 10 μm.

9. A method for fabricating a light-emitting device, characterized in that, The preparation method includes: Multiple monochromatic light-emitting structures (50) are transferred onto a substrate (10) such that the multiple monochromatic light-emitting structures (50) are arranged at intervals; A passivation layer (21) covering each of the monochromatic light-emitting structures (50) is formed on the substrate (10). A connection trace (40) and an electrode (30) are formed on the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50). The connection trace (40) is electrically connected to the monochromatic light-emitting structure (50) through a via in the passivation layer (21), and the electrode (30) is connected to the connection trace (40). A protective layer (22) is formed on the surface of the passivation layer (21) away from the monochromatic light-emitting structure (50), and the surface of the protective layer (22) has a groove (220) exposing the electrode (30).

10. A display panel, characterized in that, The display panel includes a plurality of light-emitting devices, a driving integrated circuit, and a circuit board as described in any one of claims 1 to 8, wherein the plurality of light-emitting devices and the driving integrated circuit are all located on the circuit board.

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