Light Emitting Diode and its Manufacturing Method

Abstract

This invention discloses a light-emitting diode (LED) and its fabrication method. The LED includes: a light-emitting epitaxial layer, comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, with a first electrode region on its upper surface, including a pad region and an extension region; a transparent conductive layer formed on the surface of the first semiconductor layer of the light-emitting epitaxial layer, and forming a first opening in the pad region to expose the surface of the first semiconductor layer located in the pad region; a protective layer formed on the surface of the transparent conductive layer, forming a second opening and a third opening in the pad region and the extension region of the first electrode region, respectively, to expose the surface of the first semiconductor layer located in the pad region and the surface of the transparent conductive layer located in the extension region; and a first electrode formed on the protective layer, which directly contacts the first semiconductor layer in the pad region through the first and second openings.

Description

Technical Field

[0001] This invention relates to semiconductor devices, and more particularly to a light-emitting diode and a method for manufacturing the same. Background Technology

[0002] Because of its advantages such as long lifespan, small size, high shock resistance, low heat generation, and low power consumption, LEDs have been widely used in household appliances and as indicator lights or light sources for various instruments.

[0003] Early gallium nitride (GaN) LED chip fabrication processes typically consisted of four steps: mesa etching (MESA), fabrication of a transparent conductive layer (e.g., ITO), electrode fabrication, and protective layer fabrication. The resulting LED chip, such as... Figure 1 As shown, it generally includes a substrate 101, an N-type layer 111, a light-emitting layer 112, a P-type layer 113, a transparent conductive layer 120, a P-electrode 141 (pad 143 and extension bar 144), an N-electrode 142, and a protective layer 130. In gallium nitride LEDs, p-GaN typically causes current congestion at the bottom of the PAD due to its low carrier mobility. Therefore, a current blocking layer 150 is usually added to the bottom of the P-type electrode to suppress over-injection of current and increase current diffusion in the transparent conductive layer, such as... Figure 2 As shown, the chip fabrication process typically includes at least five steps: mesa etching (MESA), fabrication of a current blocking layer, fabrication of a current spreading layer (e.g., ITO), fabrication of electrodes, and fabrication of a protective layer. Summary of the Invention

[0004] This invention provides a light-emitting diode and its manufacturing method. After forming a transparent conductive layer, a protective layer is first formed, and then an electrode is finally formed. The protective layer can also serve as a current blocking layer, which can reduce the process and effectively improve the luminous efficiency of the light-emitting diode.

[0005] According to a first aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, wherein a first electrode region is provided on the upper surface of the epitaxial layer, the epitaxial layer including a pad region and an extension region; a transparent conductive layer formed on the surface of the first semiconductor layer, wherein a first opening is formed in the pad region to expose the surface of the first semiconductor layer located in the pad region; a protective layer formed on the surface of the transparent conductive layer, wherein a second opening and a third opening are formed in the pad region and the extension region of the first electrode region, respectively, to expose the surface of the first semiconductor layer located in the pad region and the surface of the transparent conductive layer located in the extension region; and a first electrode formed on the protective layer, which directly contacts the first semiconductor layer in the pad region through the first and second openings.

[0006] The present invention also provides a method for fabricating a light-emitting diode, comprising the following steps: (1) forming a light-emitting epitaxial layer, which includes a first semiconductor layer, a light-emitting layer and a second semiconductor layer from top to bottom; (2) defining a first electrode region on the upper surface of the light-emitting epitaxial layer, which includes a pad region and an extension region; (3) forming a transparent conductive layer on the upper surface of the light-emitting epitaxial layer, which forms a first opening in the pad region to expose the surface of the first semiconductor layer in the pad region of the first electrode region; (4) forming a protective layer on the transparent conductive layer, which forms a second opening and a third opening in the pad region and the extension region of the first electrode region, respectively, to expose the surface of the first semiconductor layer in the pad region and the surface of the transparent conductive layer in the extension region; (5) fabricating a first electrode, which is formed on the protective layer and directly contacts the first semiconductor layer in the pad region through the first and second openings.

[0007] In some embodiments, the upper surface of the light-emitting epitaxial layer is further provided with a second electrode region, the second electrode region forming a mesa that exposes a portion of the surface of the second semiconductor layer, and the protective layer simultaneously covering the surface of the mesa and forming a fourth opening structure. Furthermore, the light-emitting diode also includes a second electrode formed on the protective layer and in contact with the surface of the second semiconductor layer through the fourth opening structure.

[0008] In some embodiments, the size of the second opening is larger than the size of the first opening, and the first electrode is in contact with both the first semiconductor layer and the transparent conductive layer in the pad area.

[0009] In some embodiments, the second opening is an annular structure, wherein the inner diameter of the annular structure is smaller than the diameter of the first opening, and the outer diameter is larger than the diameter of the first opening.

[0010] Preferably, the thickness d of the protective layer is λ / 4n×(2k-1), where λ is the emission wavelength of the light-emitting layer, n is the refractive index of the protective layer, and k is a natural number greater than or equal to 1. More preferably, k is a natural number greater than or equal to 2. For example, in some embodiments, the thickness of the protective layer can be 200~250nm.

[0011] In some embodiments, the first electrode has a high-low undulation shape on the upper surface of the extended region.

[0012] In some embodiments, the upper surface of the first electrode in the pad area is lower than its upper surface at the height of the extension area.

[0013] In some embodiments, the pads of the first electrode are stepped.

[0014] In some embodiments, the protective layer forms a plurality of fifth openings around the pad area to expose the transparent conductive layer, and the first electrode extends a plurality of metal tentacles from the pad area to the fifth openings to contact the transparent conductive layer.

[0015] In some embodiments, the second opening is annular and has at least one tentacles extending away from the pad area, through which the first electrode contacts the transparent conductive layer.

[0016] According to a second aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, wherein a first electrode region is provided on its upper surface, comprising a pad region and an extension region; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the surface of the transparent conductive layer, wherein a first opening and a second opening are formed in the pad region and the extension region, respectively, exposing the surface of the transparent conductive layer, wherein the first opening is annular and has at least one tentacle extending away from the pad region; and a first electrode formed on the protective layer and electrically connected to the second semiconductor layer through the first and second openings.

[0017] In some embodiments, the upper surface of the light-emitting epitaxial layer is further provided with a second electrode region, the second electrode region forming a mesa that exposes a portion of the surface of the second semiconductor layer, and the protective layer simultaneously covering the surface of the mesa and forming a third opening structure. Further, the light-emitting diode also includes a second electrode formed on the protective layer and in contact with the surface of the second semiconductor layer through the fourth opening structure.

[0018] In some embodiments, the antennae are located within the pad area.

[0019] In some embodiments, the antenna extends beyond the pad area.

[0020] Preferably, the number of antennae is 1 to 20.

[0021] In some embodiments, the transparent conductive layer forms a fourth opening in the pad area, exposing the surface of the first semiconductor layer located in the pad area.

[0022] Preferably, the inner diameter of the first opening is smaller than the diameter of the fourth opening, and the outer diameter is larger than the diameter of the fourth opening.

[0023] In some embodiments, the outer diameter of the first opening is smaller than the diameter of the fourth opening, the outer diameter of the antenna is larger than the diameter of the fourth opening, and the diameter of the fourth opening is smaller than the diameter of the pad area.

[0024] According to a third aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, wherein a first electrode region is provided on its upper surface, comprising a pad region and an extension region; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the surface of the transparent conductive layer, wherein a series of first openings are formed around the pad region, and a second opening is formed in the extension region, exposing the surface of the transparent conductive layer; a first electrode formed on the protective layer, comprising a pad, an extension strip, and a contact, wherein the two ends of the contact are respectively connected to the pad and the first opening, and the extension strip is connected to the transparent conductive layer through the second opening.

[0025] In some embodiments, the protective layer has an annular third opening structure in the pad area.

[0026] In some embodiments, the transparent conductive layer has a fourth opening structure in the pad area.

[0027] Preferably, the inner diameter of the third opening is smaller than the diameter of the fourth opening, and the outer diameter is larger than the diameter of the fourth opening.

[0028] Preferably, the diameter of the fourth opening is greater than the outer diameter of the third opening and less than the inner tangent circle diameter of the first opening.

[0029] In some embodiments, the pads are in contact with both the protective layer and the transparent conductive layer.

[0030] In some embodiments, the upper surface of the light-emitting epitaxial layer is further provided with a second electrode region, the second electrode region forming a mesa that exposes a portion of the surface of the second semiconductor layer, and the protective layer simultaneously covering the surface of the mesa and forming a fifth opening structure. Further, the light-emitting diode also includes a second electrode formed on the protective layer and in contact with the surface of the second semiconductor layer through the fifth opening structure.

[0031] Preferably, the number of antennae is 1 to 20.

[0032] According to a fourth aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; and a first electrode comprising a pad and an extension strip, wherein the extension strip is formed on the protective layer and electrically connected to the first semiconductor layer through a series of vias, and a portion of the upper surface of the extension strip is higher than the upper surface of the pad.

[0033] Preferably, the extension strip and the protective layer form an all-angle reflector.

[0034] Preferably, the protective layer is an optically rarefied dielectric layer.

[0035] In some embodiments, the transparent conductive layer forms a first opening at the location corresponding to the pad.

[0036] In some embodiments, the protective layer forms a second opening at the location corresponding to the pad.

[0037] Preferably, the size of the second opening is larger than the size of the first opening.

[0038] Preferably, the pad is in contact with the protective layer, the transparent conductive layer, and the P-type layer simultaneously.

[0039] Preferably, the second opening is an annular structure, with its inner diameter being smaller than the diameter of the first opening and its outer diameter being larger than the diameter of the first opening.

[0040] Preferably, the light-emitting diode further includes a second electrode formed on the protective layer, comprising pads and an extension strip, wherein a portion of the upper surface of the extension strip is higher than the upper surface of the pads of the first electrode.

[0041] According to a fifth aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; a first electrode comprising pads and an extension strip, electrically connected to the first semiconductor layer; and a second electrode comprising pads and an extension strip, wherein the extension strip is formed on the protective layer and electrically connected to the second semiconductor layer through a series of through-holes penetrating the protective layer, the transparent conductive layer, the first semiconductor layer, and the light-emitting layer, and a portion of the upper surface of the extension strip is higher than the upper surface of the pads of the first electrode.

[0042] Preferably, the extension strip of the second electrode and the protective layer form a full-angle reflector.

[0043] Preferably, the protective layer is an optically rarefied dielectric layer.

[0044] In some embodiments, the transparent conductive layer forms a first opening at a position corresponding to the pad of the first electrode.

[0045] In some embodiments, the protective layer forms a second opening at a location corresponding to the pad of the electrode.

[0046] Preferably, the size of the second opening is larger than the size of the first opening.

[0047] In some embodiments, the pads of the first electrode are stepped.

[0048] In some embodiments, the extension strip of the second electrode is a closed loop structure.

[0049] In some embodiments, a portion of the upper surface of the pad of the second electrode is higher than the upper surface of the pad of the first electrode.

[0050] In some embodiments, the second electrode is distributed in the central region of the light-emitting diode, wherein the pad is located at the center and the extension strip extends from the pad to opposite ends.

[0051] According to a sixth aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; a first electrode comprising pads and extension strips, electrically connected to the first semiconductor layer; and a second electrode formed on the protective layer, comprising pads and extension strips, electrically connected to the second semiconductor layer through a series of vias, wherein the upper surface of the pads is at the same height as the upper surface of the extension strips.

[0052] Preferably, the extension strip of the second electrode and the protective layer form a full-angle reflector.

[0053] Preferably, the ratio of the diameter of the through hole corresponding to the pad of the second electrode to the diameter of the pad of the second electrode is 1:2 to 1:20.

[0054] Preferably, the area of ​​the via below the pad of the second electrode accounts for 2% to 60% of the area of ​​the pad of the second electrode.

[0055] In some embodiments, the transparent conductive layer forms a first opening at a position corresponding to the first electrode pad.

[0056] In some embodiments, the protective layer forms a second opening at a location corresponding to the first electrode pad.

[0057] Preferably, the size of the second opening is larger than the size of the first opening.

[0058] Preferably, the pads of the first electrode are in contact with the protective layer, the transparent conductive layer, and the P-type layer simultaneously.

[0059] In some embodiments, the pads of the first electrode are stepped.

[0060] In some embodiments, a portion of the upper surface of the pad of the second electrode is higher than the upper surface of the pad of the first electrode.

[0061] In some embodiments, the second electrode is distributed in the central region of the light-emitting diode, wherein the pad is located at the center and the extension strip extends from the pad to opposite ends.

[0062] According to a seventh aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; a first electrode electrically connected to the first semiconductor layer; and a second electrode formed on the protective layer, comprising a pad and an extension strip, wherein a first through-hole is provided in the protective layer below the pad, and a second through-hole is provided in the protective layer below the extension strip, wherein the diameter of the first through-hole is less than or equal to the diameter of the second through-hole.

[0063] Preferably, the number of the first through holes is more than one, and when there is more than one, the through holes are centrally symmetrically distributed.

[0064] Preferably, the total area of ​​the first through hole accounts for 2% to 50% of the pad area of ​​the second electrode.

[0065] Preferably, a single first via occupies 1% to 5% of the pad area of ​​the second electrode.

[0066] In some embodiments, the upper surface of the pad of the second electrode and the upper surface of the extension strip of the second electrode are flush.

[0067] In some embodiments, the protective layer below the extension strip of the first electrode is provided with a series of third through holes, exposing the surface of the transparent conductive layer.

[0068] In some embodiments, the pads of the first electrode are formed on the protective layer and contact the transparent conductive layer through the extension strip.

[0069] In some embodiments, the transparent conductive layer beneath the first electrode pad has an opening structure.

[0070] In some embodiments, the protective layer beneath the first electrode pad has an open structure.

[0071] In some embodiments, the pads of the first electrode are stepped.

[0072] According to an eighth aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; a first electrode comprising a pad and an extension strip, wherein the extension strip is formed on the protective layer and a series of first through-holes penetrating the protective layer are provided below it, and the extension strip is connected to the transparent conductive layer through the first through-holes; a second electrode comprising a pad and an extension strip, wherein the extension strip is formed on the protective layer and a series of second through-holes penetrating the protective layer, the transparent conductive layer, the first semiconductor layer, and the light-emitting layer are provided below it, and the extension strip is connected to the second semiconductor layer through the second through-holes; wherein the distance from at least one of the three consecutive first through-holes to the nearest second through-hole does not exceed the distance between the extension strip of the first electrode and the extension strip of the second electrode.

[0073] Preferably, the extension strip of the first electrode is parallel to the extension strip of the second electrode.

[0074] Preferably, the line connecting at least one of the three consecutive first through holes to the nearest second through hole is perpendicular to the extension strip of the first electrode.

[0075] Preferably, the relationship between the distance d1 between two adjacent first through holes and the distance d2 between two adjacent second through holes is: d2≥2d1.

[0076] In some embodiments, the transparent conductive layer beneath the first electrode pad has a first opening structure that exposes the first semiconductor layer.

[0077] In some embodiments, the protective layer beneath the first electrode pad has a second opening structure.

[0078] Preferably, the size of the second opening is larger than the size of the first opening.

[0079] In some embodiments, the pads of the first electrode are stepped.

[0080] Preferably, the upper surface of the extension strip of the first electrode has an undulating wavelength shape.

[0081] Preferably, the upper surface of the extension strip of the second electrode has an undulating wavelength shape.

[0082] According to a ninth aspect of the present invention, a light-emitting diode includes: a light-emitting epitaxial layer comprising, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer; a transparent conductive layer formed on the surface of the first semiconductor layer; a protective layer formed on the transparent conductive layer; a first electrode electrically connected to the first semiconductor layer; and a second electrode formed on the protective layer, comprising a pad and an extension strip, wherein the protective layer below the pad has a first opening structure exposing the surface of the second semiconductor layer, and the pad is in contact with both the second semiconductor layer and the protective layer.

[0083] In some embodiments, the first opening is annular.

[0084] In some embodiments, the first electrode includes a pad and an extension strip, wherein the transparent conductive layer beneath the pad has a second opening structure that exposes the first semiconductor layer.

[0085] In some embodiments, the protective layer beneath the first electrode pad has a third opening structure.

[0086] In some embodiments, the size of the third opening is larger than the size of the second opening.

[0087] In some embodiments, the pads of the first electrode are stepped.

[0088] In some embodiments, the upper surface of the extension strip of the first electrode has an undulating wavelength shape.

[0089] In some embodiments, the upper surface of the first electrode pad is lower than a portion of the upper surface of the extension strip of the first electrode.

[0090] In some embodiments, the upper surface of the first electrode pad is lower than a portion of the upper surface of the extension strip of the second electrode.

[0091] In some embodiments, the upper surface of the extension strip of the second electrode has an undulating wavelength shape.

[0092] The present invention includes at least the following beneficial effects:

[0093] (1) The above-mentioned light-emitting diode first forms a protective layer on the transparent conductive layer and then forms an electrode. The protective layer protects the light-emitting diode from damage on the one hand, and on the other hand, it can be directly used as a current blocking layer to suppress the over-injection of current under the electrode and increase the current diffusion of the transparent conductive layer.

[0094] (2) The first electrode of the above-mentioned light-emitting diode is directly connected to the semiconductor layer in the pad area, which effectively increases the adhesion between the electrode and the epitaxial layer and reduces the risk of the electrode falling off from the bonding interface during wire bonding.

[0095] (3) Form tentacles on the outer periphery of the pad area of ​​the first electrode to increase the contact area between the pad area of ​​the first electrode and the transparent conductive layer, alleviate the current congestion effect on the pad area and the extended area, and reduce the risk of electrode metal precipitation and burnout.

[0096] (4) The design of the protective layer utilizes the refractive effect to reduce the metal light-blocking area of ​​the electrode extension area and improve the light extraction efficiency of the LED;

[0097] (5) The design of the protective layer forms a full-angle reflector, which can improve the reflectivity of the electrode extension area and reduce the light absorption efficiency;

[0098] (6) The above-mentioned light-emitting diode first forms a protective layer on the transparent conductive layer and then forms an electrode, which can reduce the probability of the active metal in the electrode structure being oxidized during the fabrication of the protective layer.

[0099] (7) The above method for manufacturing light-emitting diodes combines the fabrication of the current blocking layer and the protective layer into one process, which simplifies the process.

[0100] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings.

[0101] While the invention will be described below in conjunction with some exemplary embodiments and methods of use, those skilled in the art will understand that it is not intended to limit the invention to these embodiments. Rather, it is intended to cover all alternatives, modifications, and equivalents that fall within the spirit and scope of the invention as defined in the appended claims. Attached Figure Description

[0102] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Furthermore, the figures are descriptive outlines and are not drawn to scale.

[0103] Figure 1 This is a schematic diagram of an existing light-emitting diode (LED).

[0104] Figure 2 This is a schematic diagram of another existing light-emitting diode structure.

[0105] Figure 3 This is a schematic diagram of the structure of the light-emitting diode according to Embodiment 1 of the present invention.

[0106] Figure 4 This is a top view of the light-emitting diode of Embodiment 1 of the present invention.

[0107] Figure 5This is a photomask diagram of the fabrication of a light-emitting diode according to Embodiment 2 of the present invention.

[0108] Figures 6-8 This is a cross-sectional schematic diagram of the fabrication of a light-emitting diode according to Embodiment 2 of the present invention.

[0109] Figure 9 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 3 of the present invention.

[0110] Figure 10-11 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 4 of the present invention.

[0111] Figure 12-13 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 5 of the present invention.

[0112] Figure 14-15 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 6 of the present invention.

[0113] Figure 16-17 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 7 of the present invention.

[0114] Figure 18 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 8 of the present invention.

[0115] Figure 19 yes Figure 18 The diagram shows the interface reflection effect between the electrode extension strip and the protective layer of the light-emitting diode.

[0116] Figure 20 yes Figure 18 The diagram shows the light extraction effect of the electrode extension strip structure of the light-emitting diode.

[0117] Figure 21 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 9 of the present invention.

[0118] Figure 22 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 10 of the present invention.

[0119] Figure 23 This is a schematic diagram of the structure of the light-emitting diode according to Embodiment 11 of the present invention.

[0120] Figure 24 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 12 of the present invention.

[0121] Figure 25 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 13 of the present invention.

[0122] Figure 26 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 14 of the present invention.

[0123] Figure 27 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 15 of the present invention.

[0124] Figure 28 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 16 of the present invention.

[0125] Figure 29 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 17 of the present invention.

[0126] Figure 30 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 18 of the present invention.

[0127] Figure 31 This is a schematic diagram of the structure of the light-emitting diode in Embodiment 19 of the present invention. Detailed Implementation

[0128] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention. Example

[0129] like Figure 3 As shown, a light-emitting diode includes: a substrate 201, an N-type layer 211, a light-emitting layer 212, a P-type layer 213, a transparent conductive layer 220, a semiconductor protective layer 230, a first electrode 241, and a second electrode 242.

[0130] Specifically, the substrate 201 is selected from, but is not limited to, sapphire, aluminum nitride, gallium nitride, silicon, and silicon carbide, and its surface structure can be a planar structure or a patterned structure; an N-type layer 211 is formed on the sapphire substrate 201; a light-emitting layer 212 is formed on the N-type layer 211; a P-type layer 213 is formed on the light-emitting layer 212; a transparent conductive layer 220 is formed on the P-type layer 213; a semiconductor protective layer 230 is formed on the transparent conductive layer 220; and a first electrode 241 and a second electrode 242 are formed on the semiconductor protective layer 230. Figure 4 Showing Figure 3 The top view of the light-emitting diode shown shows that the first electrode 241 is composed of a pad 243 and an extension bar 244, and the second electrode 242 is composed of a pad 245 and an extension bar 246.

[0131] Please refer to the following: Figure 3 and Figure 4The transparent conductive layer 220 forms a first opening 251 at the position corresponding to the pad 243 of the first electrode, and the semiconductor protective layer 230 forms a second opening 252 at the position corresponding to the pad 243 of the first electrode, and a third opening 253 at the position corresponding to the extension strip 244 of the first electrode, exposing the transparent conductive layer 220. Specifically, the second opening 252 is a ring-shaped structure, with the inner ring 252a having a diameter D2 smaller than the diameter D1 of the first opening 252, and the outer ring 252b having a diameter D3 larger than the diameter D1 of the first opening 251. Figure 4 The image also shows a partial enlarged view of the pad area of ​​the first electrode before electrode formation. It can be seen that, from the outside in, the exposed surface of the pad area of ​​the first electrode consists of a semiconductor protective layer 230, a transparent conductive layer 221 located within the second opening, a P-type layer 213a, and the semiconductor protective layer 231. The pad 243 of the first electrode formed above this layer can simultaneously contact the P-type layer 213a, the transparent conductive layer 220, and the semiconductor protective layer 230. Below the pad portion 243 of the first electrode is the semiconductor protective layer 231, which acts as a current blocking layer. When energized, most of the current is injected into the transparent conductive layer 220 through the third opening 253 via the extension strip 244. A small portion of the current is injected into the transparent conductive layer 220 through the portion 221 of the pad portion 243 that contacts the transparent conductive layer, and then injected into the light-emitting epitaxial layer after expansion within the transparent conductive layer 220.

[0132] The semiconductor protective layer 230 can be made of SiO2, Si3N4, Al2O3, or TiO2; in this embodiment, SiO2 is selected. In this embodiment, the semiconductor protective layer 230 serves two purposes: protecting the surface of the light-emitting diode and acting as a current blocking layer to suppress over-injection of current below the electrodes and increase current diffusion in the transparent conductive layer. Therefore, its thickness must balance both requirements, and its thickness d is λ / 4n×(2k-1), where λ is the emission wavelength of the light-emitting layer 212, n is the refractive index of the protective layer, and k is a natural number greater than or equal to 1. Preferably, k is 2 to 3, corresponding to a thickness of 150nm to 500nm. Too small a thickness is less conducive to functioning as a current blocking layer and providing protection, while too large a thickness will increase light loss due to material absorption.

[0133] In this embodiment, the light-emitting epitaxial layer forms a mesa and a series of vias 256 penetrating the P-type layer 213 and the light-emitting layer 212, exposing part of the surface of the N-type layer 211. The semiconductor protective layer 230 covers the sidewalls of the vias 256, the sidewalls between the transparent conductive layer 220 and the mesa, and the surface of the mesa. A fourth opening 254 is reserved at the mesa, which is annular. The second electrode 242 is fabricated on the surface of the semiconductor protective layer 230. The pad portion 245 contacts the N-type layer through the fourth opening 254, and the extension strip 246 contacts the N-type layer 211 through the vias 256.

[0134] Furthermore, the semiconductor protective layer 230 described in this embodiment is preferably a transparent dielectric material, which, together with the extension strip of the electrode, can form a full-angle reflector, thereby improving the reflection efficiency of the metal-dielectric interface and reducing the absorption and loss of light by the metal.

[0135] In this embodiment, the protective layer of the aforementioned light-emitting diode protects the light-emitting diode from damage and also serves as a current blocking layer to suppress over-injection of current below the electrode and increase current diffusion in the transparent conductive layer. The first electrode is directly attached to the semiconductor layer in the pad area, effectively increasing the adhesion between the electrode and the epitaxial layer and reducing the risk of electrode detachment from the attachment interface during wire bonding. The pad portion of the first electrode adopts a multi-step design to effectively buffer the impact force of wire bonding and reduce the impact and damage to the first electrode pad during the wire bonding process. The extension strip of the second electrode is located on the protective layer and contacts the transparent conductive layer through a protective hole, so that the extension strip of the first electrode forms an upper and lower wave shape, increasing the light emission angle at the extension strip and improving the light extraction efficiency. Example

[0136] This embodiment discloses a method for fabricating a light-emitting diode, which mainly includes four processes: mesa etching (MESA), fabrication of a transparent conductive layer, fabrication of a semiconductor protective layer, and fabrication of electrodes. Figure 5 This shows the corresponding photomask patterns involved in these four processes. The following section combines... Figure 5-8 A brief explanation is provided.

[0137] First, a light-emitting epitaxial layer structure is provided, which generally includes a substrate 201, an N-type layer 211, a light-emitting layer 212, and a P-type layer 213.

[0138] Next, refer to Figure 5 The pattern shown in (a) defines a first electrode region and a second electrode region on the surface of the light-emitting epitaxial layer, removes the void region, and forms a mesa 210 for the second electrode and a series of through holes 256, as shown in the figure. Figure 6 As shown;

[0139] Next, refer to Figure 5 The pattern shown in (b) involves fabricating a transparent conductive layer 220 on the P-type layer 213 of the light-emitting epitaxial layer, etching away the open area, forming an opening 251 in the pad area of ​​the first electrode region, and forming an opening 257 at the position corresponding to the via 255, as shown. Figure 7 As shown;

[0140] Next, refer to Figure 5As shown in (c), a semiconductor protective layer 230 is fabricated on the transparent conductive layer 220, removing the open area. This protective layer 230 simultaneously covers the sidewalls of the via 256, the sidewalls between the transparent conductive layer 220 and the mesa, and the surface of the mesa 210. An opening 252 is formed in the pad area of ​​the first electrode region, an opening 253 is formed in the extension area of ​​the first electrode region, an opening 254 is formed on the mesa 210, and an opening 255 is formed in the extension area of ​​the second electrode. Preferably, the opening 252 is an annular structure, with the inner ring 252a having a diameter D2 smaller than the diameter D1 of the opening 252, and the outer ring 252b having a diameter D3 larger than the diameter D1 of the opening 251. In this case, the exposed surface of the pad area of ​​the first electrode, from the outside to the inside, consists of the semiconductor protective layer 230, the transparent conductive layer 221, the P-type layer 213a, and the semiconductor protective layer 231, as shown. Figure 8 As shown;

[0141] Next, refer to Figure 5 The pattern shown in (d) indicates that a first electrode 241 and a second electrode 242 are fabricated on a semiconductor protective layer 230. The pad portion of the first electrode 241 is in contact with the P-type layer, the transparent conductive layer, and the protective layer simultaneously.

[0142] It should be noted that the shape and size of the opening 252 are not limited to those described above. It can also be formed into a non-annular structure. For example, in some embodiments, there is no protective layer 231 structure below the center of the pad portion of the first electrode, and it is in direct contact with the P-type layer 213. In other embodiments, the opening 252 can also be designed as a series of tentacles distributed around the pad area, exposing the transparent conductive layer. The pad area does not form an opening structure. In this case, the pad portion of the first electrode is completely formed on the protective layer 230 and can be connected to the tentacles through metal leads. Example

[0143] Figure 9 This diagram shows another type of light-emitting diode (LED) structure. Unlike Embodiment 1, in this embodiment, the diameter D1 of the second opening 252 is greater than or equal to the diameter D1 of the first opening. In this case, there is no semiconductor protective layer below the pad 243 of the first electrode 241, and it directly contacts the P-type layer 213. The pad portion of the first electrode directly contacts the semiconductor, and the adhesion between the electrode and the GaN interface is good, reducing the risk of the first electrode detaching from the bonding interface. Example

[0144] Figure 10-11A schematic diagram of another light-emitting diode (LED) structure is shown. Unlike Embodiment 1, in this embodiment, the second opening 252 is annular and has at least one antenna 252c extending away from the pad area. The number of antennas 252c varies from 1 to 20. The pad portion 243 of the first electrode contacts the transparent conductive layer through this antenna 252c. This increases the contact area between the pad portion of the first electrode and the transparent conductive layer, facilitating current diffusion and alleviating the current congestion effect on the pad portion and extension strip of the first electrode, thus reducing the risk of metal deposition and electrode burnout. Example

[0145] Figure 12-13 A schematic diagram of another light-emitting diode structure is shown. Unlike embodiment 4, in the light-emitting diode structure described in this embodiment, the transparent conductive layer does not form an opening in the pad area of ​​the first electrode, and the pad portion 243 of the first electrode is in direct contact with the transparent conductive layer 221 and the protective layer. Example

[0146] Figure 14-15 A schematic diagram of another light-emitting diode (LED) structure is shown. Unlike Embodiment 5, in this embodiment, the transparent conductive layer 220 forms a first opening 251 at the position corresponding to the pad 243 of the second electrode. This opening 251 is located between the outer periphery 252b of the second opening and the outer periphery of the antenna 252c. The antenna 252c at the edge of the second opening 252 extends beyond the pad portion 243 of the first electrode. The pad portion 243 of the first electrode contacts the transparent conductive layer through the antenna 252c outside the first opening 251. This reduces the contact area between the pad portion of the first electrode and the transparent conductive layer, lowering the risk of the transparent conductive layer being broken during wire bonding. Simultaneously, the design of multiple steps effectively buffers the impact force of wire bonding, reducing the impact and damage to the pad of the first electrode during the wire bonding process. Example

[0147] Figure 16-17 A schematic diagram of another type of light-emitting diode is shown, in which... Figure 16 The pattern of the semiconductor protective layer 230 and the pattern of the electrodes are shown. Unlike Embodiment 1, in the light-emitting diode structure described in this embodiment, the semiconductor protective layer 230 forms a series of openings 257 around the pad area of ​​the first electrode, exposing the transparent conductive layer 220. The pad portion of the first electrode extends tentacles 247 to connect to the openings 257, and the number of tentacles 252c varies from 1 to 20.

[0148] It should be noted that in some modified embodiments, the transparent conductive layer 220 may not need to form an opening structure in the pad area. In other embodiments, neither the transparent conductive layer 220 nor the semiconductor protective layer 230 forms an opening in the pad area of ​​the first electrode. In this case, the pad portion 243 of the first electrode is completely formed on the protective layer and does not contact the transparent conductive layer 220 or the P-type layer 213. Example

[0149] Figure 18 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. Unlike Embodiment 1, in the light-emitting diode structure of this embodiment, the opening 251 of the transparent conductive layer 220 in the first electrode pad region has the same size as the opening 252 of the semiconductor protective layer in the first electrode pad region. In this embodiment, the thickness of the protective layer 230 is preferably 200 nm or more. Figure 18 As can be seen from the cross-sectional view cut along line AA, the upper surface 243a of the pad portion of the first electrode is significantly lower than the upper surface 244a of the upper portion of the extension strip 244.

[0150] exist Figure 1 In the illustrated LED structure, secondary light emitted from the light-emitting layer, reflected back from the bottom or sidewall, reaches the interface between the P-electrode extension strip 144 and the P-type layer, resulting in metal absorption and a loss of light extraction efficiency. Similarly, light from the N-electrode and light reflected multiple times from the bottom also experiences metal absorption at the interface between the P-electrode extension strip 144 and the P-type layer, leading to further loss of light extraction efficiency. In this embodiment, a protective layer 230 is added to the area directly below the extension strip 244 of the first electrode. This protective layer is preferably made of a transparent dielectric material. The protective layer 230 and the extension strip 244 of the first electrode can form an all-angle reflector. Figure 19 Showing Figure 1 The diagram shows the reflection of the light-emitting diode and the electrode extension strip of the light-emitting diode shown in this embodiment. As can be seen from the diagram, in this embodiment, the extension strip 244 and the protective layer 230 form an all-angle reflector, which effectively improves the reflection efficiency of the metal-dielectric interface and reduces the absorption loss of light by the metal.

[0151] Furthermore, the semiconductor protective layer 230 can be made of an optically sparse material (relative to the P-type semiconductor layer, such as GaN), in which case the semiconductor protective layer has a refractive effect, such as... Figure 20 As shown, if the light-shielding length of the extension strip 244 of the first electrode is ab, in this embodiment, a material with a refractive effect is used as the protective layer 230, and the light-shielding length of the extension strip 244 of the first electrode is shortened to ac. Example

[0152] Figure 21A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode, where the cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. In this embodiment, the size of the opening 251 of the transparent conductive layer 220 in the pad area of ​​the first electrode is smaller than the opening 252 of the semiconductor protective layer 230 in the pad area of ​​the first electrode, and the pad portion of the first electrode is in contact with the surfaces of both the P-type layer 213 and the transparent conductive layer.

[0153] In this embodiment, the light-emitting epitaxial layer forms a mesa and a series of vias 255 penetrating the P-type layer 213 and the light-emitting layer 212, exposing part of the surface of the N-type layer 211. The semiconductor protective layer 230 covers the sidewall of the via 255, the sidewall between the transparent conductive layer 220 and the mesa, and the surface of the mesa, and reserves a fourth opening at the mesa. The second electrode 242 is fabricated on the surface of the semiconductor protective layer 230, wherein the pad portion 245 contacts the N-type layer through the fourth opening, and the extension strip 246 contacts the N-type layer through the via 255.

[0154] Specifically, the extension strips 246 of the second electrode are located in the middle of the chip and contact the n-type layer through several vias 255. The upper surface of the extension strips 246 in the non-via area is higher than the upper surface of the pads 243 of the first electrode. The designed height difference range is 50nm~500nm. The height difference described in this embodiment is a recommended range and not a limiting condition. The end of the extension strips 246 of the first electrode can end at the shortest distance of the covered vias, or it can be extended appropriately, but it cannot directly contact the pads of the first electrode. Figure 21 As shown.

[0155] In this embodiment, the extension strip 246 of the second electrode and the protective layer below it form a full-angle reflector, improving the reflection efficiency of the metal-dielectric interface and reducing the absorption loss of light by the metal. Similarly, the material of the protective layer can be an optically rarefied medium with refractive properties, which effectively shortens the light-shielding area of ​​the second electrode extension strip. The principle is the same as in Embodiment 8. Figure 20 As shown.

[0156] Furthermore, the bottom of the extension strip of the second electrode is provided with a through hole 255 that penetrates the P-type layer and the light-emitting layer, so that the extension strip forms an upper and lower wave shape, increasing the effective area of ​​ITO and improving the light extraction efficiency. Example

[0157] Figure 22 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 9, in this embodiment, the extension strip 246 of the second electrode contacts the N-type layer through a strip-shaped opening. Example

[0158] Figure 23 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 9, the extension strip 246 of the second electrode in this embodiment adopts a double-row structure, as shown in the figure. Example

[0159] Figure 24 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 9, the extension strip 246 of the second electrode in this embodiment adopts a double-row structure and has a normal interdigitated structure, as shown in the figure. Example

[0160] Figure 25 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 9, the extension strip 246 of the second electrode in this embodiment adopts a closed-loop structure, wherein the extension strip 244 of the first electrode is located inside the extension strip 246 of the second electrode, as shown in the figure. Example

[0161] Figure 26 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 9, in this embodiment, the light-emitting epitaxial layer does not form a mesa. The pad 245 and extension strip 246 of the second electrode are both in contact with the N-type layer 211 through vias. At this time, the upper surfaces of the non-via areas of the pad 245 and extension strip 246 of the second electrode are basically flush, both exceeding the upper surface 243a of the pad of the first electrode, as shown in the figure.

[0162] Specifically, one or more through holes may be provided below the pad 245 of the second electrode. The ratio of the diameter of a single through hole to the diameter of the pad of the second electrode is preferably 1:2 to 1:20. The total area of ​​all through holes accounts for 2% to 60% of the area of ​​the pad 245 of the second electrode. As the number of holes increases, the proportion of holes also increases.

[0163] In this embodiment, holes are drilled only at the bottom of the pads of the second electrode for contacting the N-type connector, which can effectively increase the area of ​​ITO and facilitate better current injection. At the same time, most of the pads of the second electrode are above the protective layer, which is beneficial for light extraction. Example

[0164] Figure 27 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. The cross-sectional view mainly illustrates the specific structure of the pad portion 243 of the first electrode and the second electrode. Unlike Embodiment 15, the second electrode extension strip 246 in this embodiment adopts a bidirectional structure. Specifically, the second electrode is distributed in the central region of the chip, with the pad 245 located at the center, and the extension strip 246 extending from the pad to opposite ends, as shown in the figure. Example

[0165] Figure 28 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. Unlike Embodiment 1, in this embodiment, the semiconductor protective layer 230 substantially completely covers the surface of the light-emitting diode, with an opening 253 (gray-filled portion) formed only below the extension strip 244 of the first electrode, a through-hole 258 formed below the pad of the second electrode, and a through-hole 255 formed below the extension strip of the second electrode. Therefore, the pad of the first electrode is formed directly on the protective layer, and the transparent conductive layer 220 is injected through the opening 253 below the extension strip.

[0166] In this embodiment, a through hole 258 is formed at the center position directly below the pad 245 of the second electrode, which occupies 1% to 5% of the area of ​​the pad of the second electrode. Preferably, its size is smaller than or equal to the size of the through hole 255 below the extension strip 246.

[0167] In this embodiment, the pads of the first electrode and the second electrode are basically formed directly on the protective layer. When silicon oxide is used as the semiconductor protective layer 230, it has good adhesion to the bottom layer of the pad (generally a reflective layer), which can effectively reduce the risk of the wire bonding electrode falling off. Furthermore, the bottom of the extension strip of the second electrode adopts a hole design, which can increase the effective light-emitting area of ​​the LED, thereby improving the light extraction efficiency of the chip. Example

[0168] Figure 29 A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. Unlike embodiment 16, the semiconductor protective layer 230 below the pad 245 of the second electrode forms a plurality of vias 258, which are centrally symmetrically distributed and preferably have a total area of ​​2% to 50% of the pad area of ​​the second electrode. Example

[0169] Figure 30The diagram shows a top view and a cross-sectional view along line AA of another light-emitting diode. Unlike embodiment 16, the semiconductor protective layer 230 below the extension strip 244 of the first electrode forms a series of through-holes 253, exposing the surface of the transparent conductive layer 220. Simultaneously, the transparent conductive layer 220 and the semiconductor protective layer 230 below the first electrode pads form openings 251 and 252, respectively. Opening 252 is annular, with the inner diameter of the annulus smaller than the diameter of opening 252, and the outer diameter larger than the diameter of opening 251. The first electrode pad 243 simultaneously contacts the surfaces of the P-type layer 213, the transparent conductive layer 220, and the protective layer 230 in a stepped manner, with its cross-sectional area decreasing from top to bottom. This effectively buffers the impact force of the bonding wire, reducing the impact and damage to the first electrode pads during the bonding process.

[0170] Specifically, the first electrode includes a pad 243 and an extension strip 244, and the second electrode includes a pad 245 and an extension strip 246. The extension strip 244 of the first electrode contacts the transparent conductive layer 220 through a via 253, and the extension strip 246 of the second electrode contacts the N-type layer 211 through a via 255. At least one of the three consecutive vias 253a to 253c has a distance d3 from its nearest via 253a to its nearest via 255a that does not exceed the distance d4 between the extension strip 244 of the first electrode and the extension strip 246 of the second electrode. In this embodiment, the extension strips 244 of the first electrode and 246 of the second electrode are parallel to each other. The line connecting at least one of the three consecutive vias 253a to its nearest second via 255a is substantially perpendicular to the extension strip of the first electrode. The relationship between the spacing d1 between two adjacent vias 255 and the spacing d2 between two adjacent vias 253 is: d2≈2d1.

[0171] although Figure 30 In the illustrated light-emitting diode, the pad 245 of the second electrode contacts the N-type layer 211 through a via 258. It should be understood that the pad 245 of the second electrode is not limited to this design. In some modified embodiments, the via 258 below the pad 245 of the second electrode can be replaced with an annular opening structure, for example... Figure 3 The structure shown; in some modified embodiments, the pad 245 of the second electrode may not directly contact the N-type layer, that is, the protective layer 230 completely covers the N-type layer below the pad 245, and the second electrode contacts the N-type layer 211 through the through hole 255 below the extension strip 246; in other modified embodiments, the pad 245 of the second electrode may directly contact the N-type layer 211, that is, the protective layer 230 does not cover the N-type layer below the pad 245. Example

[0172] Figure 31A top view and a cross-sectional view along line AA are shown for another type of light-emitting diode. Unlike embodiment 16, the protective layer below the pad 243 of the first electrode forms a shaped opening 252, and the pad 245 of the second electrode is formed directly on the surface of the N-type layer without a protective layer underneath.

[0173] In this embodiment, the size of the through hole 253 below the extension strip 244 of the first electrode is slightly smaller than the through hole 255 below the extension strip of the second electrode. Among the four consecutive through holes 253a~253d, only the first and last through holes 253a and 253d have through holes 255 corresponding to them. At this time, the relationship between the distance d1 between two adjacent through holes 255 and the distance d2 between two adjacent through holes 253 is: d2≈3d1.

[0174] It should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the scope of the claims.

Claims

1. A light-emitting diode, including: The light-emitting epitaxial layer includes, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer, and its upper surface is provided with a first electrode region, which includes a pad region. A transparent conductive layer is formed on the surface of the first semiconductor layer, and a first opening is formed in the pad area to expose the surface of the first semiconductor layer located in the pad area; A protective layer is formed on the surface of the transparent conductive layer, and a second opening is formed in the pad area of ​​the first electrode region to expose the surface of the first semiconductor layer located in the pad area and the surface of the transparent conductive layer located in the pad area. The protective layer has a block structure located in the first opening and has a gap with the transparent conductive layer. The first electrode is formed on the protective layer and contacts the first semiconductor layer of the pad area through the gap.

2. The light-emitting diode according to claim 1, characterized in that: The first electrode region has an extension region, the protective layer forms a third opening in the extension region, the first electrode has an extension strip, and the extension strip forms an electrical connection with the transparent conductive layer through the third opening.

3. The light-emitting diode according to claim 2, characterized in that: The third opening is distributed along the extension strip.

4. The light-emitting diode according to claim 2, characterized in that: The third opening is a series of pore-like structures with interspersed gaps.

5. The light-emitting diode according to claim 2, characterized in that: The upper surface of the light-emitting epitaxial layer is further provided with a second electrode region, which forms a mesa and exposes part of the surface of the second semiconductor layer. The protective layer simultaneously covers the surface of the mesa and forms a fourth opening structure.

6. The light-emitting diode according to claim 1, characterized in that: The second opening is a ring-shaped structure, wherein the inner diameter of the ring is smaller than the diameter of the first opening, and the outer diameter is larger than the diameter of the first opening.

7. The light-emitting diode according to claim 1, characterized in that: The protective layer forms several fifth openings around the pad area, exposing the transparent conductive layer. The first electrode extends several metal tentacles from the pad area to the fifth openings and contacts the transparent conductive layer.

8. The light-emitting diode according to claim 1, characterized in that: The second opening is annular and contains at least one tentacle extending away from the pad area, through which the first electrode contacts the transparent conductive layer.

9. Light-emitting diodes, including: The light-emitting epitaxial layer comprises, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. The light-emitting epitaxial layer has a mesa that exposes the second semiconductor layer. A transparent conductive layer is formed on the surface of the first semiconductor layer; A protective layer is formed on the surface of the transparent conductive layer, and simultaneously covers the surface of the transparent conductive layer, the surface of the exposed first semiconductor layer, the surface of the mesa, and the sidewall between the first semiconductor layer and the mesa. A first electrode is formed on the protective layer and electrically connected to the first semiconductor layer through the transparent conductive layer, including a first pad and a first extension strip; The second electrode is formed on the protective layer and electrically connected to the second semiconductor layer, including a second pad and a second extension strip, wherein the second pad is located on the mesa; The protective layer has a fourth opening located below the second pad, through which the second pad contacts the second semiconductor layer, and a gap exists between the second pad and the edge of the fourth opening.

10. The light-emitting diode according to claim 9, characterized in that: The second extension strip contacts the second semiconductor layer through a through-hole.

11. The light-emitting diode according to claim 9, characterized in that: The protective layer includes a second opening located below the first pad, through which the first pad contacts the transparent conductive layer and the first semiconductor layer.

12. A light-emitting diode, including: The light-emitting epitaxial layer comprises, from top to bottom, a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. The light-emitting epitaxial layer has a mesa that exposes the second semiconductor layer. A transparent conductive layer is formed on the surface of the first semiconductor layer, and a first opening is formed in the pad area to expose the surface of the first semiconductor layer located in the pad area; A protective layer is formed on the surface of the transparent conductive layer, and simultaneously covers the surface of the transparent conductive layer, the surface of the exposed first semiconductor layer, the surface of the mesa, and the sidewall between the first semiconductor layer and the mesa. A first electrode is formed on the protective layer and electrically connected to the first semiconductor layer through the transparent conductive layer, including a first pad and a first extension strip; The second electrode is formed on the protective layer and electrically connected to the second semiconductor layer, and includes a second pad and a second extension bar; The protective layer has a third opening below the first extension strip and a sixth opening below the second extension strip. The first extension strip contacts the transparent conductive layer through the third opening, and the second extension strip contacts the second semiconductor layer through the sixth opening. The spacing d1 between adjacent third openings is greater than the spacing d2 between adjacent sixth openings.

13. The light-emitting diode according to claim 12, characterized in that: The relationship between d1 and d2 is: d2≈2d1.

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