Light-emitting unit and micro light-emitting element

Abstract

The invention relates to the technical field of semiconductors, in particular to a light-emitting unit and a micro light-emitting element. The light-emitting unit comprises an epitaxial structure and an insulating layer, and the epitaxial structure is provided with a first surface and a second surface which are opposite to each other; the epitaxial structure comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked from a first surface to a second surface; the epitaxial structure is provided with a table surface, and the table surface exposes the first semiconductor layer and faces the second surface; the insulating layer extends from the second surface to cover the table top. Through the design of the insulating layer, stripping of the temporary substrate is facilitated, the process yield of mass transfer is improved, the problem of cracks of the epitaxial structure in the stripping process can be avoided, and the performance of the light-emitting unit is further improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a light-emitting unit and a micro-light-emitting element. Background Art

[0002] Micro LED display technology refers to a display technology that uses self-luminous micron-sized LEDs (Micro LEDs) as light-emitting pixel units and assembles multiple Micro LEDs onto a driving panel to form a high-density LED array. Due to its characteristics such as small size, high integration, and self-luminescence, in terms of display, compared with conventional LCDs and OLEDs, it has greater advantages in terms of brightness, resolution, contrast, energy consumption, lifespan, response speed, and thermal stability.

[0003] Micro LED cannot be mass-produced at present because there are still many technical problems to be overcome. One important technical problem is how to improve the manufacturing yield of Micro LED. Summary of the Invention

[0004] In view of at least one deficiency of the above-mentioned existing technology, an embodiment of the present invention provides a light-emitting unit, which at least includes an epitaxial structure and an insulating layer.

[0005] The epitaxial structure has opposite first and second surfaces; the epitaxial structure includes a first semiconductor layer, an active layer, and a second semiconductor layer that are sequentially stacked from the first surface to the second surface; the epitaxial structure is configured with a mesa that exposes the first semiconductor layer and faces the second surface; the insulating layer extends from the second surface to cover the mesa.

[0006] The present invention also provides a micro-light-emitting element, which includes: a substrate and at least one light-emitting unit located on the substrate; the light-emitting unit adopts the light-emitting unit described in the above embodiment.

[0007] Based on the above, compared with the existing technology, the light-emitting unit provided by the present invention, through the design of the insulating layer, not only facilitates the peeling of the temporary substrate and improves the manufacturing yield of Micreo LED, but also can avoid the problem of cracks in the epitaxial structure during the peeling process, further improving the performance of the light-emitting unit.

[0008] Other features and beneficial effects of the present invention will be described in the subsequent specification, and part of them will become obvious from the specification, or will be understood by implementing the present invention. The objectives and other beneficial effects of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings; the positional relationships described in the following drawings, unless otherwise specified, are all based on the directions of the components shown in the drawings.

[0010] Figures 1 to 3 A cross-sectional view of the light-emitting unit of each embodiment in Embodiment 1 provided by the present invention;

[0011] Figures 4 to 5 A cross-sectional view of the light-emitting unit of other embodiments in Embodiment 1 provided by the present invention;

[0012] Figure 6 For Figure 5 The top view of the light-emitting unit in

[0013] Figure 7 A cross-sectional view of the light-emitting unit of an embodiment in Embodiment 2 provided by the present invention;

[0014] Figure 8 For Figure 7 The top view of the light-emitting unit in

[0015] Figure 9 A cross-sectional view of the light-emitting unit of an embodiment in Embodiment 3 provided by the present invention;

[0016] Figure 10 A cross-sectional view of the light-emitting unit of other embodiments in Embodiment 3 provided by the present invention.

[0017] Reference numerals:

[0018] 10 - epitaxial structure; 11 - first semiconductor layer; 12 - active layer; 13 - second semiconductor layer; 20 - insulating layer; 31 - first electrode; 32 - second electrode; 40 - temporary substrate. Detailed implementation manners

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention; the technical features designed in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0020] In the description of the present invention, it should be noted that all terms used in the present invention (including technical terms and scientific terms) have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention pertains, and should not be construed as a limitation of the present invention; it should be further understood that the terms used in the present invention should be understood as having meanings consistent with their meanings in the context of this specification and the relevant art, and should not be understood in an idealized or overly formal sense, unless otherwise clearly defined in the present invention.

[0021] The present invention provides a light-emitting unit, which at least includes an epitaxial structure 10 and an insulating layer 20. The epitaxial structure 10 has opposite first and second surfaces; the epitaxial structure 10 includes a first semiconductor layer 11, an active layer 12, and a second semiconductor layer 13 that are sequentially stacked from the first surface to the second surface; the epitaxial structure 10 is configured with a mesa, the mesa exposes the first semiconductor layer 11 and faces the second surface; the insulating layer 20 extends from the second surface to cover the mesa. Through the arrangement of the insulating layer 20, it is beneficial to the peeling of the temporary substrate 40, improves the process yield of mass transfer, and can also avoid the problem of cracks in the epitaxial structure 10 during the peeling process.

[0022] In one embodiment, at least one end of the insulating layer 20 is located on the mesa or on the sidewall of a part of the epitaxial structure 10 on the side of the mesa to protect the mesa. The extension height H4 of the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the mesa is less than the height H6 of the sidewall of the epitaxial structure 10 on the side of the mesa, that is, it is ensured that the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the mesa does not extend to the first surface of the epitaxial structure 10. Thus, while being beneficial to the peeling of the temporary substrate 40, the epitaxial structure 10 is more effectively protected and the light-emitting efficiency is improved.

[0023] In one embodiment, the distance H5 from the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the mesa to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to 100 Å, or between 100 Å and 1000 Å, or between 1000 Å and 10000 Å. Specifically, it can be designed according to the actual thickness of the epitaxial structure 10.

[0024] In one embodiment, the insulating layer 20 extends from the second surface to cover the sidewall of a part of the epitaxial structure 10 on the side of the second surface. The extension height H1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the second surface is less than the height H3 of the sidewall of the epitaxial structure 10 on the side of the second surface, so as to ensure that the insulating layer 20 on the sidewall of the epitaxial structure 10 does not extend to the first surface of the epitaxial structure 10. Thus, while being beneficial to the peeling of the temporary substrate 40, the epitaxial structure is more effectively protected and the light-emitting efficiency is improved.

[0025] In one embodiment, the distance H2 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the side of the second surface to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to 100 angstroms, or between 100 and 1000 angstroms, or between 1000 angstroms and 10000 angstroms. Specifically, it can be designed according to the actual thickness of the epitaxial structure 10.

[0026] In one embodiment, the thickness of the insulating layer 20 on the sidewall of the epitaxial structure 10 near the second surface or the mesa is greater than the thickness near the first surface, so as to improve the manufacturing yield and the light extraction efficiency.

[0027] In one embodiment, the insulating layer 20 on the sidewall of the epitaxial structure 10 extends to cover a part of the sidewall of the first semiconductor layer 11, so as to reduce the defects of non-radiative recombination, and further improve the light emission efficiency of the light-emitting unit.

[0028] In one embodiment, the first semiconductor layer 11 includes a nitride undoped region, and the sidewall of the epitaxial structure 10 not covered by the insulating layer 20 is the nitride undoped region. Among them, the nitride undoped region is non-conductive, and extending the insulating layer 20 to the nitride undoped region can effectively prevent short circuits.

[0029] In one embodiment, the distance H2 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the side of the second surface to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to the height of the first semiconductor layer 11, and / or, the distance H5 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the side of the mesa to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to the height of the first semiconductor layer 11. To ensure that the insulating layer 20 extends to cover the sidewall of the first semiconductor layer 11 and does not extend to the first surface of the epitaxial structure 10, the optoelectronic effect and the transfer yield can be taken into account at the same time.

[0030] In one embodiment, the insulating layer 20 on the sidewall of the epitaxial structure 10 is a Bragg reflection layer or a passivation layer.

[0031] In one embodiment, the insulating layer 20 on the sidewall of the epitaxial structure 10 is a passivation layer to passivate the sidewall of the epitaxial structure 10, and the insulating layer 20 located on the second surface of the epitaxial structure 10 and extending to cover the mesa is a Bragg reflection layer, so as to achieve the effect of electrical isolation and at the same time facilitate light reflection to the light extraction surface.

[0032] In one embodiment, the insulating layer 20 on the sidewall of the epitaxial structure 10 and the insulating layer 20 located on the second surface of the epitaxial structure 10 and extending to cover the mesa may have the same or different materials.

[0033] In one embodiment, the thickness D1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 is less than the thickness D2 of the insulating layer 20 on the second surface of the epitaxial structure 10.

[0034] In one embodiment, the thickness D1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 ranges from 0.01 to 5 μm.

[0035] In one embodiment, the material of the insulating layer 20 includes silicon oxide, silicon nitride, titanium oxide, aluminum oxide, or magnesium fluoride.

[0036] In one embodiment, the short side length of the light-emitting unit is not greater than 30 μm, which is more convenient for mass transfer in this embodiment.

[0037] In one embodiment, the insulating layer 20 forms a first opening on the mesa to expose the first semiconductor layer 11; the insulating layer 20 forms a second opening on the second surface of the epitaxial structure 10 to expose the second semiconductor layer 13; the light-emitting unit further includes a first electrode 31 located on the insulating layer 20 and electrically connected to the first semiconductor layer 11 through the first opening; a second electrode 32 located on the insulating layer 20 and electrically connected to the second semiconductor layer 13 through the second opening; and a transparent conductive layer located between the second electrode 32 and the second semiconductor layer 13 to achieve an optoelectronic effect.

[0038] In one embodiment, the light-emitting unit further includes a temporary substrate 40 located on one side of the first surface of the epitaxial structure 10.

[0039] The present invention also provides a micro-light-emitting element, which includes a substrate and at least one light-emitting unit located on the substrate. The light-emitting unit adopts the light-emitting unit described in any of the above embodiments to effectively improve the process yield of the micro-light-emitting element.

[0040] Hereinafter, the technical solutions of the present invention will be clearly and completely described through various specific embodiments in combination with the accompanying drawings in the embodiments of the present invention.

[0041] Embodiment 1

[0042] Please refer to Figure 1 , Figure 1 is a cross-sectional view of a light-emitting unit provided by an embodiment of the present invention. To achieve at least one of the above advantages or other advantages, the light-emitting unit provided by an embodiment of the present invention at least includes an epitaxial structure 10 and an insulating layer 20. The epitaxial structure 10 has opposite first and second surfaces; the epitaxial structure 10 includes a first semiconductor layer 11, an active layer 12, and a second semiconductor layer 13 that are sequentially stacked from the first surface to the second surface.

[0043] The epitaxial structure 10 is disposed on a temporary substrate 40, which can be a semiconductor substrate. For example, the material of the temporary substrate 40 is a growth substrate with a bandgap greater than 4.5 eV, such as sapphire or silicon carbide.

[0044] A first semiconductor layer 11 is disposed on the temporary substrate 40. In some embodiments, the first semiconductor layer 11 is N-type doped. For example, the first semiconductor layer 11 may include a II-VI group material (e.g., zinc selenide (ZnSe)) or a III-V nitride group compound material (e.g., gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), or aluminum indium gallium nitride (AlInGaN)), and the first semiconductor layer 11 may include dopants such as silicon (Si) or germanium (Ge), but the embodiments of the present disclosure are not limited thereto. In the embodiments of the present disclosure, the first semiconductor layer 11 can be a single-layer or multi-layer structure.

[0045] Refer to Figure 1 , an active layer 12 is disposed on the first semiconductor layer 11. In some embodiments, the active layer 12 may include at least one undoped semiconductor layer or at least one lightly doped layer. For example, the active layer 12 can be a quantum well (QW) layer, which may include indium gallium nitride (InxGa1-xN) or gallium nitride (GaN), but the embodiments of the present disclosure are not limited thereto. In some embodiments, the active layer 12 can also be a multiple quantum well (MQW) layer, but the embodiments of the present disclosure are not limited thereto.

[0046] Refer to Figure 1 , a second semiconductor layer 13 is disposed on the active layer 12. In some embodiments, the second semiconductor layer 13 is P-type doped. For example, the second semiconductor layer 13 may include a II-VI group material (e.g., zinc selenide (ZnSe)) or a III-V nitride group compound material (e.g., gallium nitride (GaN), aluminum nitride (AlN), indium nitride (InN), indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), or aluminum indium gallium nitride (AlInGaN)), and the second-type semiconductor material 40 may include dopants such as magnesium (Mg) or carbon (C), but the embodiments of the present disclosure are not limited thereto. In the embodiments of the present disclosure, the second semiconductor layer 13 can be a single-layer or multi-layer structure.

[0047] Of course, the epitaxial structure 10 may further include other layer materials, such as a window layer or an ohmic contact layer, etc., which are set as different multi-layers according to different doping concentrations or component contents.

[0048] Furthermore, the epitaxial structure 10 is configured with a mesa that exposes the first semiconductor layer 11 and faces the second surface. The mesa can be configured, for example, as Figures 1 to 3 formed by etching the second semiconductor layer, the active layer, and a part of the first semiconductor layer only at the outer edge of the epitaxial structure 10 to expose the first semiconductor layer, or as Figures 4 to 6 formed by etching the second semiconductor layer, the active layer, and a part of the first semiconductor layer only inside the epitaxial structure 10 to expose the first semiconductor layer, or as in the second embodiment Figures 7 to 10 shown, formed by etching the second semiconductor layer, the active layer, and a part of the first semiconductor layer only on one side of the epitaxial structure 10 to expose the first semiconductor layer. It should be noted that the disclosed embodiments of the present invention are not limited to these mesa configuration methods.

[0049] Wherein, the insulating layer 20 extends from the second surface to cover the mesa. Preferably, at least one end of the insulating layer 20 is located on the mesa or on the sidewall of the partial epitaxial structure 10 on the side of the mesa. That is, as Figure 1 shown, at least one end edge of the insulating layer 20 can extend from the second surface to cover the entire mesa having the first electrode 31; or, as Figure 2 , Figure 4 shown, at least one end edge of the insulating layer 20 can extend from the second surface to cover only a part of the mesa; or, as Figure 3 , Figure 5 shown, further extend to cover the sidewall of the partial epitaxial structure 10 on the side of the mesa. Specifically, it can be designed according to actual requirements and is not limited herein. The above designs of the insulating layer 20 all ensure that the insulating layer 20 does not extend to the first surface of the epitaxial structure 10.

[0050] Please refer to Figure 3 , Figure 5 . When the insulating layer 20 is on the sidewall of the partial epitaxial structure 10 on the side of the mesa, the extension height H4 of the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the mesa is less than the height H6 of the sidewall of the epitaxial structure 10 on the side of the mesa. That is, the insulating layer 20 on the sidewall of the epitaxial structure 10 on the side of the mesa does not extend and contact the edge of the first surface.

[0051] Specifically, as Figure 3 , Figure 5As shown, the height of the insulating layer 20 extending from the mesa surface towards the first surface is defined as H4, and the height of the sidewall of the epitaxial structure 10 from the mesa surface to the first surface is defined as H6. The insulating layer 20 on the sidewall of the epitaxial structure 10 located on the mesa sidewall does not extend to the first surface of the epitaxial structure 10. Preferably, the distance H5 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the mesa side to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to 100 Å, or between 100 - 1000 Å, or between 1000 Å - 10000 Å. Specifically, it can be designed according to the actual thickness of the epitaxial structure 10, and no limitation is made here.

[0052] In this embodiment, the insulating layer 20 extending and covering the mesa surface on the second surface is a passivation layer or a Bragg reflector layer. When the insulating layer 20 is a passivation layer, it suppresses the probability of electrons and holes recombining on the sidewalls of the active layer 12, improving the light emission efficiency of the light emitting unit. When the insulating layer 20 is a Bragg reflector layer formed by stacking materials such as silicon oxide (SiO2), aluminum nitride (AlN), and silicon nitride (SiN), it can increase the forward light emission. Therefore, the material of the insulating layer 20 includes but is not limited to silicon oxide, silicon nitride, titanium oxide, aluminum oxide, or magnesium fluoride, and is specifically designed according to actual working requirements, and no limitation is made here.

[0053] Through the above setting of the insulating layer 20, it is not only beneficial to the peeling of the temporary substrate 40, improving the process yield of mass transfer, but also can avoid defects such as cracks in the epitaxial structure 10 or damage to the insulating layer 20 caused by the connection between the insulating layer 20 and the temporary substrate 40 during the peeling process, and improve the reliability of the light emitting unit.

[0054] Preferably, the short side length of the light emitting unit is not greater than 30 μm, so as to be applied to microscale light emitting diodes.

[0055] In other embodiments, the insulating layer 20 forms a first opening on the mesa to expose the first semiconductor layer 11; the insulating layer 20 forms a second opening on the first surface of the epitaxial structure 10 to expose the second semiconductor layer 13. The light emitting unit further includes a first electrode 31 and a second electrode 32. Among them, the first electrode 31 is located on the insulating layer 20 and is electrically connected to the first semiconductor layer 11 through the first opening, and the second electrode 32, the second electrode 32 is located on the insulating layer 20 and is electrically connected to the second semiconductor layer 13 through the second opening. The first electrode 31 and the second electrode 32 are made of a metal material, such as at least one of nickel, gold, chromium, titanium, platinum, palladium, rhodium, iridium, aluminum, tin, indium, tantalum, copper, cobalt, iron, ruthenium, zirconium, tungsten, and molybdenum, or at least one of an alloy or laminate selected from the above materials. As an example, the first electrode 31 is an N electrode and the second electrode 32 is a P electrode.

[0056] In other embodiments, the light-emitting unit further includes a transparent conductive layer and / or a current blocking layer (not shown in the figure) to suppress the current aggregation phenomenon near the electrode and improve the current spreading performance. As an example, the transparent conductive layer may be indium tin oxide (ITO) or indium zinc oxide (IZO). In this embodiment, an ITO layer formed by evaporation or sputtering process is preferably used. The current blocking layer may be SiO2, Si3N4, Al2O3, TiO2 or their composite structure.

[0057] Embodiment 2

[0058] Please refer to Figure 7 、 Figure 8 , which is different from Embodiment 1: In this embodiment, the insulating layer 20 extends from the second surface to cover a part of the sidewall of the epitaxial structure 10 on the side of the second surface. Among them, the extension height H1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the sidewall of the second surface is less than the height H3 of the sidewall of the epitaxial structure 10 on the side of the second surface. That is, the insulating layer 20 located on the sidewall of the epitaxial structure 10 does not extend and contact the edge of the first surface.

[0059] Specifically, as Figure 7 shown, the height of the insulating layer 20 extending from the second surface of the epitaxial structure 10 towards the first surface is defined as H1, and the height of the sidewall of the epitaxial structure 10 from the second surface to the first surface is defined as H3. The insulating layer 20 located on the sidewall of the second surface does not extend to the first surface of the epitaxial structure 10. Preferably, the distance H2 between the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the sidewall of the second surface and the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to 100 Å, or between 100 - 1000 Å, or between 1000 Å - 10000 Å, and can be specifically set according to the actual thickness of the epitaxial structure 10, which is not limited here.

[0060] Embodiment 3

[0061] Compared with Embodiment 1 and Embodiment 2, further, the insulating layer 20 located on the sidewall of the epitaxial structure 10 extends to cover a part of the sidewall of the first semiconductor layer 11, that is, the insulating layer 20 can completely cover the sidewall of the active layer 12, thereby effectively reducing the defects of non-radiative recombination and improving the light-emitting efficiency. For example Figure 3 、 Figure 5 、 Figure 7As shown. Preferably, the distance H2 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the side of the second surface to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to the height of the first semiconductor layer 11, and / or the distance H5 from the insulating layer 20 on the sidewall of the epitaxial structure 10 located on the side of the mesa to the first surface of the epitaxial structure 10 is greater than 0 and less than or equal to the height of the first semiconductor layer 11. Through the above limitations, it is ensured that the insulating layer 20 extends to cover part of the sidewall of the first semiconductor layer 11 and does not extend to the first surface of the epitaxial structure 10, which can take into account both the optoelectronic effect and the transfer yield.

[0062] Furthermore, the first semiconductor layer 11 includes a nitride undoped region, and the sidewall of the epitaxial structure 10 not covered by the insulating layer 20 is the nitride undoped region. In other words, the insulating layer 20 on the sidewall of the epitaxial structure 10 extends to cover part of the nitride undoped region. Among them, since the nitride undoped region is non-conductive, extending the insulating layer 20 to part of the nitride undoped region can effectively prevent the risk of short circuit.

[0063] Furthermore, please refer to Figure 9 , the thickness of the insulating layer 20 on the sidewall of the epitaxial structure 10 near the second surface or the mesa end is greater than the thickness near the first surface end. This design can further improve the manufacturing yield and the light extraction efficiency.

[0064] In other embodiments, the insulating layer 20 on the sidewall of the epitaxial structure 10 and the insulating layer 20 on the second surface of the epitaxial structure 10 and extending to cover the mesa may be the same or different in material. In this embodiment, it is preferred that the insulating layer 20 on the sidewall of the epitaxial structure 10 is a passivation layer, which may be, for example, aluminum oxide (Al2O3) or hafnium dioxide (HfO2) coated by atomic layer deposition (ALD), or silicon dioxide (SiO2) / silicon nitride (SiXNX) coated by chemical vapor deposition (CVD). And the insulating layer 20 on the second surface of the epitaxial structure 10 and extending to cover the mesa may be, for example, a Bragg reflection layer formed by overlapping silicon dioxide (SiO2) / titanium dioxide (TiO2) using an evaporation or sputtering process.

[0065] As Figure 10As shown, in this embodiment, the thickness D1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 is less than the thickness D2 of the insulating layer 20 on the second surface of the epitaxial structure 10. Among them, the thicker insulating layer 20 with thickness D2 directly covers the first semiconductor layer 11 to ensure the effect of electrical passivation. The thinner insulating layer 20 with thickness D1 covers the sidewall of the epitaxial structure 10, serving to passivate the sidewall of the epitaxial structure 10 to improve the light-emitting efficiency. Preferably, the thickness D1 of the insulating layer 20 on the sidewall of the epitaxial structure 10 ranges from 0.1 to 5 μm. Among them, the sidewall of the epitaxial structure 10 may include the sidewall of the epitaxial structure 10 on the side of the second surface and the sidewall of the epitaxial structure 10 on the side of the mesa.

[0066] Embodiment 4

[0067] An embodiment of the present invention further provides a micro-light-emitting element, which includes a substrate and at least one light-emitting unit. Specifically, the side of the light-emitting unit away from the temporary substrate 40 is bonded to the substrate, and then the temporary substrate 40 is peeled off. Among them, the specific structure, function, and role of the light-emitting unit can be referred to the foregoing Embodiment 1 and Embodiment 2, and will not be elaborated here.

[0068] Since the insulating layer of the light-emitting unit provided in the above embodiment does not extend to the temporary substrate, during the peeling process, the insulating layer will not be damaged, and at the same time, the damage to the epitaxial structure can be reduced, effectively improving the process yield and structural reliability of the micro-light-emitting element.

[0069] In addition, those skilled in the art should understand that although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be regarded as a limitation to that claim.

[0070] Although terms such as epitaxial structure, first semiconductor layer, active layer, second semiconductor layer, insulating layer, first electrode, second electrode, temporary substrate, substrate, light-emitting unit, micro-light-emitting element, etc. are used more in this article, the possibility of using other terms is not excluded. Using these terms is only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention; the terms "first", "second", etc. (if any) in the specification and claims of the embodiments of the present invention and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light-emitting unit, characterized in that, The light-emitting unit includes: An epitaxial structure having opposite first and second surfaces; the epitaxial structure includes a first semiconductor layer, an active layer, and a second semiconductor layer stacked in sequence from the first surface to the second surface; the epitaxial structure is configured with a mesa; the mesa exposes the first semiconductor layer and faces the second surface; An insulating layer that extends from the second surface to cover the mesa.

2. The light-emitting unit according to claim 1, wherein: At least one end of the insulating layer is located on the mesa or on a sidewall of a partial epitaxial structure on the side of the mesa, and the extension height H4 of the insulating layer on the sidewall of the epitaxial structure on the side of the mesa is less than the height H6 of the sidewall of the epitaxial structure on the side of the mesa.

3. The light-emitting unit according to claim 2, characterized in that: The distance H5 from the insulating layer on the sidewall of the epitaxial structure on the side of the mesa to the first surface of the epitaxial structure is greater than 0 and less than or equal to 100 Å, or between 100 - 1000 Å, or between 1000 Å - 10000 Å.

4. The light-emitting unit according to claim 2, characterized in that: The insulating layer extends from the second surface to cover a partial sidewall of the epitaxial structure on the side of the second surface, and the extension height H1 of the insulating layer on the sidewall of the epitaxial structure on the side of the second surface is less than the height H3 of the sidewall of the epitaxial structure on the side of the second surface.

5. The light-emitting unit according to claim 4, wherein: The distance H2 from the insulating layer on the sidewall of the epitaxial structure on the side of the second surface to the first surface of the epitaxial structure is greater than 0 and less than or equal to 100 Å, or between 100 - 1000 Å, or between 1000 Å - 10000 Å.

6. The light-emitting unit according to claim 4, wherein: The thickness of the insulating layer on the sidewall of the epitaxial structure is greater at the end close to the second surface or the mesa than at the end close to the first surface.

7. The light-emitting unit according to claim 4, wherein: The insulating layer on the sidewall of the epitaxial structure extends to cover a partial sidewall of the first semiconductor layer.

8. The light-emitting unit according to claim 7, wherein: The first semiconductor layer includes a nitride undoped region, and the sidewall of the epitaxial structure not covered by the insulating layer is the nitride undoped region.

9. The light-emitting unit according to claim 4, characterized in that: The distance H2 from the insulating layer on the sidewall of the epitaxial structure on the side of the second surface to the first surface of the epitaxial structure is greater than 0 and less than or equal to the height of the first semiconductor layer, and / or, the distance H5 from the insulating layer on the sidewall of the epitaxial structure on the side of the mesa to the first surface of the epitaxial structure is greater than 0 and less than or equal to the height of the first semiconductor layer.

10. The light-emitting unit according to claim 4, characterized in that: The insulating layer on the sidewall of the epitaxial structure is a Bragg reflector or a passivation layer.

11. The light-emitting unit according to claim 10, wherein: The insulating layer on the sidewall of the epitaxial structure is a passivation layer, and the insulating layer located on the second surface of the epitaxial structure and extending to cover the mesa is a Bragg reflector.

12. The light-emitting unit according to claim 4, characterized in that: The material of the insulating layer on the sidewall of the epitaxial structure is the same as or different from the material of the insulating layer located on the second surface of the epitaxial structure and extending to cover the mesa.

13. The light-emitting unit according to claim 4, characterized in that: The thickness D1 of the insulating layer on the sidewall of the epitaxial structure is less than the thickness D2 of the insulating layer on the second surface of the epitaxial structure.

14. The light-emitting unit according to claim 1, characterized in that: The thickness D1 range of the insulating layer on the sidewall of the epitaxial structure is 0.01 - 5 μm.

15. The light-emitting unit according to claim 1, characterized in that: The material of the insulating layer includes silicon oxide, silicon nitride, titanium oxide, aluminum oxide, or magnesium fluoride.

16. The light-emitting unit according to claim 1, characterized in that: The short side length of the light-emitting unit is not greater than 30 μm.

17. The light-emitting unit according to any one of claims 1 to 16, characterized in that: The insulating layer forms a first opening on the mesa to expose the first semiconductor layer; the insulating layer forms a second opening on the second surface of the epitaxial structure to expose the second semiconductor layer; The light-emitting unit further includes a first electrode located on the insulating layer and electrically connected to the first semiconductor layer through the first opening; a second electrode located on the insulating layer and electrically connected to the second semiconductor layer through the second opening; A transparent conductive layer is located between the second electrode and the second semiconductor layer.

18. The light-emitting unit according to claim 17, characterized in that: It further includes a temporary substrate located on one side of the first surface of the epitaxial structure.

19. A micro light-emitting element, characterized in that, The micro light-emitting element includes: A substrate; At least one light-emitting unit located on the substrate; the light-emitting unit adopts the light-emitting unit according to any one of claims 1 to 18.

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