Flip-chip light emitting diode and light emitting device

Abstract

This invention relates to the field of semiconductor manufacturing technology, and provides a flip-chip light-emitting diode (LED) comprising an epitaxial structure, a first electrode, and a second electrode. The epitaxial structure includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, with the light-emitting layer located between the first and second semiconductor layers. The first electrode is located on the epitaxial structure and electrically connected to the first semiconductor layer, and the second electrode is located on the epitaxial structure and electrically connected to the second semiconductor layer. The first electrode and / or the second electrode is a multilayer metal structure, comprising a metal reflective layer, a first barrier layer, and a conductive metal layer sequentially stacked on the first semiconductor layer. The thickest layer in the multilayer metal structure is the conductive metal layer, which is an Al layer. This design allows for effective buffering and release of internal thermal stress during subsequent use of the LED, and promotes horizontal current expansion, thereby improving device reliability.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a flip-chip light-emitting diode and a light-emitting device. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor light-emitting element, typically made of semiconductors such as GaN, GaAs, GaP, and GaAsP. Its core is a PN junction that emits light. LEDs have advantages such as high luminous intensity, high efficiency, small size, and long lifespan, and are considered one of the most promising light sources currently available. For example, LEDs, as pixels in light-emitting devices, can replace traditional liquid crystal display (LCD) devices and achieve higher image quality.

[0003] Currently, traditional flip-chip LEDs consist of contact electrodes for internal electrical contact and pad electrodes for external soldering. The pad electrodes can be used to fix the flip-chip to the packaging substrate via solder paste application and reflow soldering; alternatively, the pad electrodes can be directly made into solder electrodes and then directly soldered to fix the flip-chip to the packaging substrate. In these cases, an Au layer of approximately 1µm thickness is inserted into the internal contact electrode structure to improve the overall conductivity and thermal conductivity of the chip. This primarily utilizes the excellent conductivity and thermal conductivity of Au electrodes. However, due to the low tensile strength of Au, after the LED chip is mounted on the packaging substrate, the forces generated by the deformation of the packaging substrate during subsequent use are transmitted to the inside of the LED chip, resulting in high stress on the electrodes, especially the Au layer. This leads to insufficient buffering and release of the transmitted forces, causing problems such as detachment between the electrodes and the insulating layer, and between the electrode metal layers. Therefore, how to solve the problem of internal stress buffering and release in LED chips has become one of the technical challenges that urgently needs to be addressed by those skilled in the art. Summary of the Invention

[0004] The present invention provides a flip-chip light-emitting diode, which includes an epitaxial structure, a first electrode, and a second electrode.

[0005] The epitaxial structure includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. The light-emitting layer is located between the first and second semiconductor layers. A first electrode is located on the epitaxial structure and electrically connected to the first semiconductor layer. A second electrode is located on the epitaxial structure and electrically connected to the second semiconductor layer. The first and / or second electrodes are multilayer metal structures, each multilayer metal structure comprising a sequentially stacked metal reflective layer, a first barrier layer, and a conductive metal layer. The metal reflective layer is located between the first semiconductor layer and the first barrier layer. The thickest layer in the multilayer metal structure is the conductive metal layer, which is an Al layer.

[0006] In some embodiments, the first barrier layer includes at least one metal layer selected from Ti, Pt, and Ni layers.

[0007] In some embodiments, the thickness of the metal reflective layer is 100~400nm, and the thickness of the conductive metal layer is 600~1800nm.

[0008] In some embodiments, the multilayer metal structure further includes a second barrier layer disposed on the side of the conductive metal layer away from the first barrier layer.

[0009] In some embodiments, the second barrier layer includes at least one metal layer selected from Ti, Pt, and Ni layers.

[0010] In some embodiments, the multilayer metal structure further includes a first adhesive layer and a second adhesive layer, wherein the first adhesive layer is located on the side of the metal reflective layer away from the first barrier layer, and the second adhesive layer is located on the side of the second barrier layer away from the conductive metal layer.

[0011] In some embodiments, the first adhesive layer includes at least one metal layer selected from Cr and Ti layers, the second adhesive layer includes at least one metal layer selected from Cr and Ti layers, the thickness of the first adhesive layer ranges from 0.1 to 10 nm, and the thickness of the second adhesive layer ranges from 10 to 50 nm.

[0012] In some embodiments, the light-emitting diode further includes an insulating layer covering the epitaxial structure and having a first opening and a second opening.

[0013] In some embodiments, the light-emitting diode further includes a first pad and a second pad, the first pad being located on the insulating layer and electrically connected to the first electrode through the first opening, and the second pad being located on the insulating layer and electrically connected to the second electrode through the second opening.

[0014] In some embodiments, a transparent current spreading layer is disposed below the second electrode.

[0015] In some embodiments, the size of the light-emitting diode is less than or equal to 200 μm.

[0016] In some embodiments, the Al layer is a pure Al layer or an Al alloy layer.

[0017] In some embodiments, the first electrode and / or the second electrode have an extension portion, which is strip-shaped.

[0018] In some embodiments, the multilayer metal structure includes a plurality of Ti layers, the thickness of each Ti layer gradually increasing from bottom to top.

[0019] The present invention also provides a light-emitting device, which may employ a light-emitting diode as described in any of the above embodiments.

[0020] One advantage of this invention is that it provides a flip-chip light-emitting diode and a light-emitting device. By using a conductive metal layer (Al layer) with high tensile strength as the thickest layer in the multilayer metal structure, the internal thermal stress of the light-emitting diode can be well buffered and released during subsequent use, and the horizontal current expansion can be promoted, thereby improving the reliability of the device.

[0021] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures particularly pointed out in the description, claims, etc. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships in the drawings described below are based on the direction in which the components are drawn in the figures.

[0023] Figure 1 This is a schematic diagram of the structure of a light-emitting diode provided in an embodiment of the present invention;

[0024] Figure 2 This is a top view schematic diagram of a light-emitting diode provided in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of a multi-layered metal structure.

[0026] Figure Labels

[0027] 10-Light emitting diode; 12-Substrate; 14-Epipolar structure; 141-First semiconductor layer; 142-Light emitting layer; 143-Second semiconductor layer; 16-Insulating layer; 161-First opening; 162-Second opening; 21-First electrode; 22-Second electrode; 31-First pad; 32-Second pad; 41-First adhesive layer; 42-Metal reflective layer; 43-First barrier layer; 46-Conductive metal layer; 47-Second barrier layer; 48-Second adhesive layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "center," "lateral," "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Additionally, the term "comprising" and any variations thereof mean "at least comprising."

[0030] Please see Figure 1 , Figure 2 and Figure 3 , Figure 1 This is a schematic diagram of the structure of a flip-chip light-emitting diode 10 according to an embodiment of the present invention. Figure 2 This is a top view schematic diagram of a flip-chip light-emitting diode 10 provided in an embodiment of the present invention. Figure 3This is a schematic diagram of a multilayer metal structure. To achieve at least one or more of the aforementioned advantages, an embodiment of the present invention provides a flip-chip light-emitting diode 10. As shown in the figure, the flip-chip light-emitting diode 10 may include an epitaxial structure 14, a first electrode 21 and a second electrode 22, an insulating layer 16, a first pad 31, and a second pad 32.

[0031] The epitaxial structure 14 is disposed on the substrate 12. The substrate 12 may be an insulating substrate 12, preferably made of a transparent or translucent material. In the illustrated embodiment, the substrate 12 is a sapphire substrate 12. In some embodiments, the substrate 12 may be a patterned sapphire substrate 12, but this invention is not limited thereto. The substrate 12 may also be made of a conductive or semiconductor material. For example, the substrate 12 material may include at least one of silicon carbide, silicon, magnesium aluminum oxide, magnesium oxide, lithium aluminum oxide, aluminum gallium oxide, and gallium nitride.

[0032] The epitaxial structure 14 includes a first semiconductor layer 141, a light-emitting layer 142, and a second semiconductor layer 143. The light-emitting layer 142 is located between the first semiconductor layer 141 and the second semiconductor layer 143. That is, the first semiconductor layer 141, the light-emitting layer 142, and the second semiconductor layer 143 are sequentially stacked on the substrate 12.

[0033] The first semiconductor layer 141 may be an N-type semiconductor layer, which can provide electrons to the light-emitting layer 142 under the influence of a power source. In some embodiments, the first semiconductor layer 141 includes an N-type doped nitride layer. The N-type doped nitride layer may include one or more N-type impurities of group IV elements. The N-type impurities may include one or a combination of Si, Ge, and Sn.

[0034] The light-emitting layer 142 can be a quantum well (QW) structure. In some embodiments, the light-emitting layer 142 can also be a multiple quantum well (MQW) structure, wherein the multiple quantum well structure includes multiple quantum well layers (Wells) and multiple quantum barrier layers (Barriers) arranged alternately in a repeating manner, such as a GaN / AlGaN, InAlGaN / InAlGaN, or InGaN / AlGaN multi-quantum well structure. Furthermore, the composition and thickness of the well layers within the light-emitting layer 142 determine the wavelength of the generated light. To improve the luminous efficiency of the light-emitting layer 142, this can be achieved by changing the depth of the quantum wells, the number of paired quantum wells and quantum barriers, the thickness, and / or other characteristics within the light-emitting layer 142.

[0035] The second semiconductor layer 143 can be a P-type semiconductor layer, which can provide holes to the light-emitting layer 142 under power. In some embodiments, the second semiconductor layer 143 includes a P-type doped nitride layer. The P-type doped nitride layer may include one or more P-type impurities of group II elements. The P-type impurities may include one or a combination of Mg, Zn, and Be. The second semiconductor layer 143 can be a single-layer structure or a multilayer structure with different compositions. Furthermore, the arrangement of the epitaxial structure 14 is not limited to this, and other types of epitaxial structures 14 can be selected according to actual needs.

[0036] The first electrode 21 is located on the epitaxial structure 14 and electrically connected to the first semiconductor layer 141. The second electrode 22 is located on the epitaxial structure 14 and electrically connected to the second semiconductor layer 143. In some embodiments, a transparent current spreading layer may be disposed below the second electrode 22 to further improve conductivity and enhance the photoelectric characteristics of the flip-chip light-emitting diode 10. The transparent current spreading layer may be an ITO layer or an ITO layer doped with aluminum.

[0037] The insulating layer 16 covers the epitaxial structure 14 and may also cover a portion of the first electrode 21 and a portion of the second electrode 22. The insulating layer 16 has a first opening 161 and a second opening 162, which are located above the first electrode 21 and the second electrode 22, respectively.

[0038] The insulating layer 16 has different functions depending on its location. For example, when the insulating layer 16 covers the sidewall of the epitaxial structure 14, it can be used to prevent electrical connection between the first semiconductor layer 141 and the second semiconductor layer 143 due to leakage of conductive material, reducing the possibility of short-circuit abnormalities in the flip-chip light-emitting diode 10. However, this disclosure is not limited to this. The material of the insulating layer 16 includes a non-conductive material. The non-conductive material is preferably an inorganic material or a dielectric material. The inorganic material may include silicone. The dielectric material includes electrically insulating materials such as aluminum oxide, silicon nitride, silicon oxide, titanium oxide, or magnesium fluoride. For example, the insulating layer 16 may be silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate, or a combination thereof, such as a Bragg mirror (DBR) formed by repeatedly stacking two materials with different refractive indices.

[0039] The first pad 31 is located on the insulating layer 16 and is electrically connected to the first electrode 21 through the first opening 161. The second pad 32 is located on the insulating layer 16 and is electrically connected to the second electrode 22 through the second opening 162. The first pad 31 and the second pad 32 can be metal pads and can be formed together in the same process using the same material, thus having the same layer structure.

[0040] The first electrode 21 and / or the second electrode 22 are multilayer metal structures. For example, only the first electrode 21 may be a multilayer metal structure, or only the second electrode 22 may be a multilayer metal structure, or both the first electrode 21 and the second electrode 22 may be multilayer metal structures. A multilayer metal structure refers to a stacked structure with multiple metal layers. For blue and green flip-chip LEDs 10, the first electrode 21 and the second electrode 22 are typically multilayer metal structures with the same structure. The thickest layer in the multilayer metal structure is a conductive metal layer 46, which is an Al layer. The Al layer has both high tensile strength and excellent conductivity. By using a high-tensile-strength conductive metal layer 46 (Al layer) as the thickest layer in the multilayer metal structure, the internal thermal stress of the flip-chip LED 10 can be well buffered and released during subsequent use, thereby improving the reliability of the device.

[0041] The first electrode 21 may include a base portion located below the first opening 161 of the insulating layer 16 (this base portion is electrically connected to the first pad 31), and an extension portion extending downward from below the first opening 161 (for horizontally extending the current), the extension portion being strip-shaped. The second electrode 22 may include a base portion located below the second opening 162 of the insulating layer 16 (this base portion is electrically connected to the second pad 32), and an extension portion extending downward from below the second opening 162 (for horizontally extending the current), the extension portion being strip-shaped. In other words, the first electrode 21 and / or the second electrode 22 can be current-extending electrodes. The strip-shaped design of the extension portion enables the first electrode 21 and the second electrode 22 to have current-extending characteristics, improving current input and output.

[0042] In some embodiments, such as Figure 3As shown, the multilayer metal structure may include a metal reflective layer 42, a first barrier layer 43, and a conductive metal layer 46 stacked sequentially. The metal reflective layer 42 is located between the first semiconductor layer 141 and the first barrier layer 43, meaning that the metal reflective layer 42 is closer to the first semiconductor layer 141 than the first barrier layer 43 and the conductive metal layer 46. In other words, along the direction from the first semiconductor layer 141 to the second semiconductor layer 143 on the epitaxial structure 14, the metal reflective layer 42, the first barrier layer 43, and the conductive metal layer 46 are stacked sequentially. The metal reflective layer 42 mainly serves to reflect light (such as the light emitted by the light-emitting layer 142) to improve the light emission effect. The thickness of the metal reflective layer 42 can be 100~400nm, for example, 100~200nm, 200~300nm, 300~400nm, etc. The metal reflective layer 42 should not be too thick, as excessive thickness will lead to insufficient stability of the metal reflective layer 42. The first barrier layer 43 can play a blocking and protective role, such as protecting the metal reflective layer 42, protecting its layer structure from external water vapor erosion or migration, and protecting the stability of its material reflective function.

[0043] In some embodiments, the metal reflective layer 42 may be made of metals such as Al or Ag. The Al layer of the conductive metal layer 46 may be a pure Al layer or an Al alloy layer, such as an AlCu alloy layer.

[0044] The first barrier layer 43 includes at least one metal layer selected from Ti, Pt, and Ni. For example, the first barrier layer 43 can be a Ti layer, a combination of Ti and Ni layers, or a combination of Ti and Pt layers, etc. More preferably, for the first barrier layer 43 formed by the combination of Ti and Ni layers, specifically, the Ni layer has good thermal conductivity and good barrier effect. The Ni layer can also be used to buffer the internal stress of the multilayer metal structure to offset the stress between the upper and lower layers of the multilayer metal structure itself, especially the stress of the Al layer (conductive metal layer 46). The Ti layer can play a role in stress transition between the metal reflective layer 42 and the Ni layer, thereby improving the adhesion of the multilayer metal layers. Preferably, the thickness of the single Ni layer can be in the range of 100~500nm. The Ni layer should not be too thick, as excessive thickness will result in high internal stress. The thickness of the single Ti layer can be in the range of 30~300nm. The Ti layer should not be too thick, as excessive thickness will result in high resistance, which is not conducive to current transmission. The thickness of the single Pt layer can be in the range of 100~200nm. The Pt layer should not be too thick, as excessive thickness will result in an excessively wide bottom of the entire electrode, leading to severe light absorption and affecting the light emission characteristics of the flip-chip LED 10. In some embodiments, the structure of the first blocking layer 43 from bottom to top can be, for example, a Ti / Pt / Ti layer or a Ti / Ni / Ti layer.

[0045] The conductive metal layer 46 is an Al layer, which serves two purposes: firstly, it conducts electricity; secondly, due to the high tensile strength of the Al layer, it can buffer and release internal stress. To ensure the conductivity and tensile strength of the conductive metal layer 46, its thickness ranges from 600 nm to 1800 nm, for example, 800–1200 nm or 600–800 nm. When the thickness of the conductive metal layer 46 is controlled within this range, the resistance is low, and its lateral current transport capability is strong. The Al layer can further improve the current spreading performance of the extended portions of the first electrode 21 and the second electrode 22 (i.e., the first electrode 21 and the second electrode 22 are current spreading electrodes).

[0046] In some embodiments, such as Figure 3 As shown, the multilayer metal structure may further include a second barrier layer 47. The second barrier layer 47 is disposed on the side of the conductive metal layer 46 away from the first barrier layer 43, i.e. Figure 3 The second barrier layer 47 shown is located on the conductive metal layer 46. The second barrier layer 47 can play a blocking and protective role, protecting the layer structure of the conductive metal layer 46 below from external moisture erosion or migration, thereby improving the overall stability.

[0047] The second barrier layer 47 includes at least one metal layer selected from Ti, Pt, and Ni layers. For example, the second barrier layer 47 can be a Ti layer, a combination of Ti and Ni layers, or a combination of Ti and Pt layers, etc. Preferably, it is a combination of Ti and Pt layers, which has stable chemical properties and can effectively coat and protect the thicker conductive metal layer 46 below. The thickness of a single Ti layer can range from 30 to 300 nm; the Ti layer should not be too thick, as this will cause a high resistance. The thickness of a single Pt layer can range from 100 to 200 nm; if the Pt layer is too thick, the bottom width of the entire electrode will be too large, resulting in severe light absorption.

[0048] In some embodiments, such as Figure 3 As shown, the multilayer metal structure may further include a first adhesive layer 41 and a second adhesive layer 48. The first adhesive layer 41 is located on the side of the metal reflective layer 42 away from the first barrier layer 43. The first adhesive layer 41 of the second electrode 22 can be in direct contact with the transparent current spreading layer. The second adhesive layer 48 is located on the side of the second barrier layer 47 away from the conductive metal layer 46. On the epitaxial structure 14, along the direction from the first semiconductor layer 141 to the second semiconductor layer 143, the first adhesive layer 41, the metal reflective layer 42, the first barrier layer 43, the conductive metal layer 46, the second barrier layer 47, and the second adhesive layer 48 are sequentially arranged. The second adhesive layer 48 plays an adhesive role, which can strengthen the connection between the insulating layer 16 and the multilayer metal structure.

[0049] The first adhesive layer 41 may include at least one metal layer selected from Cr and Ti layers. For example, the first adhesive layer 41 may be a Cr layer or a Ti layer to adhere to adjacent structural layers (such as strengthening the connection between the epitaxial structure 14 and the multilayer metal structure), improve the tightness of the connection, and also have the function of light transmission. Preferably, the thickness of the first adhesive layer 41 is in the range of 0.1~10 nm.

[0050] The second adhesive layer 48 may include at least one metal layer selected from Cr and Ti layers. For example, the second adhesive layer 48 may be a Cr layer or a Ti layer to adhere to adjacent structural layers, improve the tightness of the connection, and also have the function of light transmission. Preferably, the thickness of the second adhesive layer 48 is in the range of 10~50 nm.

[0051] In a multilayer metal structure, the Ti layer not only acts as a barrier but also serves as a stress transition layer, improving adhesion between adjacent layers. For example, in a multilayer metal structure with three Ti layers, two Ti layers are located in the first barrier layer 43, serving as stress transition layers. The first Ti layer of the first barrier layer 43 is in contact with the metal reflective layer 42, and the last Ti layer of the first barrier layer 43 is in contact with the conductive metal layer 46. A third Ti layer is located between the conductive metal layer 46 and the second barrier layer 47, also serving as a stress transition layer. Preferably, in a multilayer metal structure, since the lower metal layer is covered by the upper metal layer, including the case where the upper surface and sidewalls of the lower metal layer are covered by the upper metal layer, to ensure coverage, the thickness relationship between the multiple Ti layers gradually increases from bottom to top (i.e., along the direction from the first semiconductor layer 141 to the second semiconductor layer 143) to enhance the adhesion between layers. For example, in a three-Ti layer structure, the thicknesses of the first Ti layer, the second Ti layer, and the third Ti layer are 30~100nm, 100~150nm, and 150nm~300nm respectively from bottom to top. More preferably, the thickness of each Ti layer does not exceed 300nm. A conductive metal layer 46 is provided between two adjacent Ti layers.

[0052] In some embodiments, the flip-chip LED 10 is a small-sized flip-chip LED 10, such as a MicroLED. Preferably, the size of the flip-chip LED 10 is less than or equal to 200 μm.

[0053] The present invention also provides a light-emitting device, which may employ a flip-chip light-emitting diode 10 as described in any of the above embodiments.

[0054] In summary, this invention provides a flip-chip light-emitting diode 10 and a light-emitting device. By using a conductive metal layer 46 with high tensile strength as the thickest layer in the multilayer metal structure, the internal thermal stress of the flip-chip light-emitting diode 10 can be effectively buffered and released during subsequent use, and horizontal current expansion can be promoted, thereby improving the reliability of the device. Using an Al layer as the conductive metal layer 46 also ensures the conductivity and thermal conductivity of the flip-chip light-emitting diode 10, while effectively buffering and releasing internal thermal stress during subsequent use, and promoting horizontal current expansion, thereby improving the reliability of the device.

[0055] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or the background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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 flip-chip light-emitting diode, characterized in that: The flip-chip light-emitting diode includes: The epitaxial structure, from bottom to top, includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, wherein the light-emitting layer is located between the first semiconductor layer and the second semiconductor layer; The first electrode is located on the epitaxial structure and is electrically connected to the first semiconductor layer; The second electrode is located on the epitaxial structure and is electrically connected to the second semiconductor layer; Wherein, the first electrode and / or the second electrode is a multilayer metal structure, the multilayer metal structure includes a metal reflective layer, a first barrier layer, a conductive metal layer and a second barrier layer stacked sequentially, the metal reflective layer is located between the first semiconductor layer and the first barrier layer, the thickest layer in the multilayer metal structure is the conductive metal layer, the conductive metal layer is an Al layer, and the second barrier layer is located on the conductive metal layer; The first barrier layer includes a Ni layer and two Ti layers sandwiching the Ni layer, and the second barrier layer is a combination of a Ti layer and a Pt layer, with the thickness of the Ti layer gradually increasing from bottom to top.

2. The flip-chip light-emitting diode according to claim 1, characterized in that: The thickness of the metal reflective layer is 100~400nm.

3. The flip-chip light-emitting diode according to claim 1, characterized in that: The thickness of the Ni layer is 100~500nm; the thickness of each Ti layer is 30~300nm.

4. The flip-chip light-emitting diode according to claim 1, characterized in that: The first barrier layer is a Ti / Ni / Ti layer.

5. The flip-chip light-emitting diode according to claim 1, characterized in that: The thickness of the conductive metal layer is 600nm~1800nm.

6. The flip-chip light-emitting diode according to claim 1, characterized in that: The thickness of the conductive metal layer is 600nm~800nm ​​or 800~1200nm.

7. The flip-chip light-emitting diode according to claim 1, characterized in that: The multilayer metal structure further includes a first adhesive layer and a second adhesive layer, wherein the first adhesive layer is located on the side of the metal reflective layer away from the first barrier layer, and the second adhesive layer is located on the side of the second barrier layer away from the conductive metal layer.

8. The flip-chip light-emitting diode according to claim 7, characterized in that: The first adhesive layer includes at least one metal layer selected from Cr and Ti layers, and the second adhesive layer includes at least one metal layer selected from Cr and Ti layers. The thickness of the first adhesive layer ranges from 0 to 10 nm, and the thickness of the second adhesive layer ranges from 10 to 50 nm.

9. The flip-chip light-emitting diode according to claim 1, characterized in that: The light-emitting diode further includes an insulating layer that covers the epitaxial structure and has a first opening and a second opening.

10. The flip-chip light-emitting diode according to claim 9, characterized in that: The light-emitting diode further includes a first pad and a second pad. The first pad is located on the insulating layer and is electrically connected to the first electrode through the first opening. The second pad is located on the insulating layer and is electrically connected to the second electrode through the second opening.

11. The flip-chip light-emitting diode according to claim 1, characterized in that: A transparent current spreading layer is disposed below the second electrode.

12. The flip-chip light-emitting diode according to claim 1, characterized in that: The Al layer is either a pure Al layer or an Al alloy layer.

13. The flip-chip light-emitting diode according to claim 1, characterized in that: The first electrode and / or the second electrode have an extension portion, which is strip-shaped.

14. A light-emitting device, characterized in that: The flip-chip light-emitting diode used is as described in any one of claims 1-13.

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