Light-emitting diode, manufacturing method thereof and light-emitting device

Abstract

The invention provides a light-emitting diode, a manufacturing method thereof and a light-emitting device, the light-emitting diode comprises a semiconductor epitaxial laminated layer, and a mesa structure is formed in the epitaxial laminated layer. The light emitting diode includes a first electrode connected to the first semiconductor layer of the semiconductor epitaxial stack, and a second electrode connected to the second semiconductor layer. The first electrode includes a fill electrode in the mesa structure, the fill electrode filling the mesa hole or mesa such that a surface of the fill electrode is flush with a surface side of the semiconductor epitaxial stack. Due to the formation of the filling electrode, the surface of the light-emitting diode is a flat surface on the whole, and no height difference or concave area exists, so that when the bonding pad electrode of the electrode structure is formed on the surface of the semiconductor epitaxial laminated layer, no height difference exists between the P electrode and the N electrode, and meanwhile, the spacing distance between the P electrode and the N electrode can be controlled; therefore, the effective contact area of the bonding pad electrodes on the same plane is increased, and the yield of products after transfer is improved. Besides, the appearance of the light-emitting diode has no height difference, so that the phenomenon of rupture or fracture caused by non-uniform stress in the transferring / bonding process is avoided, and the yield of products is ensured.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor devices, and in particular to a light emitting diode, a manufacturing method thereof, and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) has the advantages of self-luminescence, high efficiency, low power consumption, high brightness, high stability, ultra-high resolution and color saturation, fast response speed, and long life. It has been applied in the fields of display, optical communication, indoor positioning, biology, and medicine, and has a clear and considerable market prospect. In particular, micro light emitting diodes (Micro LED) have the advantages of small size and high integration in addition to the above advantages, so they have attracted more attention.

[0003] In the existing flip-chip light-emitting diodes, a step structure is provided between the P-type semiconductor region and the N-type semiconductor region, and the P(N) pole electrode is led out through the step structure. The formation of the step structure causes the surface area of ​​the Micro LED to be lost, and the thickness of the Micro LED in the step area becomes thinner. This results in a height difference between the pad of the P electrode and the pad of the N electrode. When the chip is smaller, the spacing between the corresponding pads of the P / N electrodes is difficult to control, making the area of ​​the equal height area between the pads corresponding to the P / N electrodes too small, and the pads of the P / N electrodes are prone to the risk of breaking. On the other hand, the height difference between the P / N electrodes makes the Micro LED as a whole form a non-flat structure with a notch, which easily causes the Micro LED to crack or break during the transfer / bonding process, affecting the yield of the product.

[0004] In light-emitting diodes, how to reduce or eliminate the adverse effects of the height difference between the pads corresponding to the P / N electrodes while ensuring the normal optoelectronic performance of the chip has become one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0005] In view of the above-mentioned deficiencies and defects of the P / N electrodes of Micro LED in the prior art, the present application provides a light emitting diode and a manufacturing method thereof and a light emitting device to solve one or more of the above-mentioned technical problems.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a light emitting diode, which at least comprises:

[0007] A semiconductor epitaxial stack, wherein the semiconductor epitaxial stack comprises a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top, and one side of the second semiconductor layer is a first surface of the light-emitting diode;

[0008] a mesa structure, which at least penetrates the second semiconductor layer and the active layer along the stacking direction of the semiconductor epitaxial stack, and the bottom of the mesa structure is located on the first semiconductor layer;

[0009] The electrode structure includes a first electrode electrically connected to the first semiconductor layer and a second electrode electrically connected to the second semiconductor layer, wherein the first electrode includes a filling electrode formed in the mesa structure, wherein the height difference between the filling electrode and the first surface is between -0.5 μm and 0.5 μm.

[0010] Another aspect of the present invention provides a light-emitting device, which includes a circuit substrate and a plurality of light-emitting elements fixed on the circuit substrate, wherein the light-emitting elements include the light-emitting diode described in the present application.

[0011] Another aspect of the present invention provides a method for manufacturing a light emitting diode, which comprises the following steps:

[0012] Forming a semiconductor epitaxial stack, the semiconductor epitaxial stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top, one side of the second semiconductor layer being a first surface;

[0013] Etching the semiconductor epitaxial stack from the first surface to form a mesa structure, wherein the mesa structure at least penetrates the second semiconductor layer and the active layer, so that the bottom of the mesa structure is located on the first semiconductor layer;

[0014] A filling electrode is formed in the mesa, and the filling electrode fills the mesa until a height difference between the filling electrode and the first surface is between -0.5 μm and 0.5 μm.

[0015] As described above, the light emitting diode and the manufacturing method thereof and the light emitting device provided by the present invention have at least the following beneficial technical effects:

[0016] The light-emitting diode of the present invention comprises a semiconductor epitaxial stack, and a mesa structure is formed in the epitaxial stack. The light-emitting diode comprises a first electrode connected to the first semiconductor layer of the semiconductor epitaxial stack, and a second electrode connected to the second semiconductor layer. The first electrode comprises a filling electrode located in the mesa structure, and the mesa structure can be a closed mesa hole or an open mesa. When the open mesa is formed, an insulating protective layer is formed above the mesa and on the side wall. The filling electrode fills the mesa hole or the mesa, so that the surface of the filling electrode is flush with the surface side of the semiconductor epitaxial stack. The formation of the filling electrode makes the surface of the light-emitting diode a flat surface as a whole, without height difference or concave area. Therefore, when the pad electrode of the electrode structure is formed on the surface of the semiconductor epitaxial stack, there will be no height difference between the P electrode and the N electrode, and it is also beneficial to control the spacing distance between the two, so that the effective contact area of ​​the pad electrode on the same plane is increased, and the yield of the product after transfer is improved. In addition, there will be no height difference in the appearance of the light-emitting diode of the present application, so that there will be no cracking or breaking due to uneven force during the transfer / bonding process, thereby ensuring the yield of the product.

[0017] The above-mentioned filling electrode of the present application can use electroplating to fill a metal layer on the table hole or table surface, or can fill the table hole or table surface with conductive materials such as conductive glue. The formation process of the filling electrode and the morphology of the filling material are easy to control, which is conducive to forming a structure with a smooth surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of a light emitting diode in the prior art.

[0019] Figure 2 It is a schematic diagram showing the structure of another light emitting diode in the prior art.

[0020] Figure 3 Shown is a schematic structural diagram of a light emitting diode provided in Embodiment 1 of the present invention.

[0021] Figure 4 A schematic structural diagram of a light emitting diode provided in an optional embodiment of the present invention is shown.

[0022] Figure 5 and Figure 6 Shown is a schematic structural diagram of a light emitting diode in an optional embodiment of the embodiment of the present invention.

[0023] Figure 7 Display as Figure 3 The schematic diagram of the top view of the insulating protection layer surface of the light emitting diode is shown.

[0024] Figure 8 Display as Figure 3The overall structural schematic diagram of the light emitting diode shown.

[0025] Fig. 9 An alternative embodiment is shown Figure 8 The schematic diagram of the top view of the structure of the light emitting diode on the wafer is shown.

[0026] Fig.10 In another alternative embodiment, Figure 8 The schematic diagram of the top view of the structure of the light emitting diode on the wafer is shown.

[0027] Fig.11 In another optional embodiment, Figure 8 The schematic diagram of the top view of the structure of the light emitting diode on the wafer is shown.

[0028] Fig.12 It is a schematic flow chart of a method for manufacturing a light emitting diode provided in the second embodiment of the present invention.

[0029] Figures 13 to 19 Display as Fig.12 Schematic diagram of the structure formed by each step in the method shown.

[0030] Fig. 20 It is a schematic diagram showing the structure of forming a filling electrode in an alternative embodiment.

[0031] Fig.21 Shown is a schematic structural diagram of a light emitting device provided in Embodiment 3 of the present invention.

[0032] Reference numerals

[0033] 10. Epitaxial structure; 11. Connecting electrodes; 12. Hole structure; 13. Terrace structure.

[0034] 100, light-emitting diode; 110, semiconductor epitaxial stack; 111, first semiconductor layer; 112, active layer; 113, second semiconductor layer; 114, table hole; 115, table; 116, insulating layer; 120, insulating protection layer; 130, electrode structure; 131, first electrode; 1311, first connecting electrode; 1312, filling electrode; 1312', metal layer; 1312", conductive glue; 1313, first contact electrode; 132, second electrode; 1311, second connecting electrode; 1322, second contact electrode; 140, seed layer; 150, shielding layer.

[0035] 200, light-emitting device; 201, light-emitting body; 202, circuit substrate; 203, circuit layer; 204, welding layer; 205, cover body. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation, the form, quantity, positional relationship and proportion of each component in actual implementation can be changed at will under the premise of realizing the technical solution of this party, and the component layout form may also be more complicated.

[0038] In the prior art, in the Micro LED manufacturing process, when forming the connecting electrode, there will be a height difference on the Micro LED surface and the effective area of ​​the connecting electrode will be small. Figure 1 A Micro LED is shown, in which a semi-enclosed hole structure 12 is formed in an epitaxial structure 10, a connecting electrode 11 is formed in the hole structure, and the connecting electrode 11 is formed on the sidewall and bottom of the hole structure 12, and climbs along the sidewall of the hole structure 12 to the surface of the epitaxial structure to form a flat portion. In this structure, the center of the hole structure 12 is not filled with the connecting electrode 11, so a concave area is formed, which results in a relatively small area of ​​the flat portion of the connecting electrode. Figure 2 Another Micro LED in the prior art is shown, in which the epitaxial structure 10 forms a mesa structure 13, and a connecting electrode 11 is formed on the mesa structure 13. The connecting electrode climbs from the surface of the mesa structure 13 along the side wall of the epitaxial structure 10 to the surface of the epitaxial structure 10 to form a flat portion. This structure more obviously causes a height difference on the surface of the Micro LED, which is not conducive to the batch transfer of Micro LEDs; at the same time, it also significantly reduces the area of ​​the flat portion of the connecting electrode, which is not conducive to the bonding of Micro LEDs. In addition, Figure 1 and Figure 2 The structures shown may cause the climbing connection electrodes 11 to crack or break, thereby reducing the product yield.

[0039] In order to solve the above problems, the present invention provides a light emitting diode and a manufacturing method thereof and a light emitting device, which are described in detail through the following specific embodiments.

[0040] Embodiment 1

[0041] This embodiment provides a light emitting diode, such as Figure 3As shown, the light emitting diode 100 of the present embodiment at least includes a semiconductor epitaxial stack 110, and the semiconductor epitaxial stack 110 of the light emitting diode 100 includes a first semiconductor layer 111, an active layer 112 and a second semiconductor layer 113 stacked in sequence from bottom to top. It is understandable that the semiconductor epitaxial stack 110 may also include other layer materials, such as a current spreading layer, a window layer or an ohmic contact layer, etc., which are arranged as different multilayers according to different doping concentrations or component contents. The epitaxial stack structure can be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD), epitaxial growth (Epitaxy Growth Technology) and atomic beam deposition (ALD).

[0042] In an alternative embodiment, the first semiconductor layer 111 may be composed of a group III-V or group II-VI compound semiconductor and may be doped with a first dopant. The first semiconductor layer 111 may be composed of a compound semiconductor having a chemical formula of In x1 Al y1 Ga 1-x1-y1 N (0≤X1≤1, 0≤Y1≤1, 0≤X1+Y1≤1) semiconductor material, such as GaN, AlGaN, InGaN, InAlGaN, etc., or a material selected from AlGaAs, GaP, GaAs, GaAsP and AlGaInP. In addition, the above-mentioned first dopant can be an n-type dopant, such as any one or more of Si, Ge, Sn, Se and Te. When the first dopant is an n-type dopant, the first semiconductor layer 111 doped with the first dopant is an n-type semiconductor layer. The first dopant can also be a p-type dopant, such as any one or more of Mg, Zn, Ca, Sr and Ba. In this case, the first semiconductor layer 111 doped with the first dopant is a p-type semiconductor layer. In an optional embodiment, the first semiconductor layer 111 of the light-emitting area 1011 serves as the light-emitting surface of the light-emitting diode 100. In order to improve the light-emitting efficiency of the light-emitting diode 100, the surface of the first semiconductor layer 111 can be roughened to form a roughened structure.

[0043] like Figure 3As shown, the active layer 112 is disposed between the first semiconductor layer 111 and the second semiconductor layer 113. The active layer 112 is a region for providing light radiation for the recombination of electrons and holes. Different materials can be selected according to different luminescent wavelengths. The active layer 112 can be a periodic structure of a single quantum well or multiple quantum wells. The active layer 112 includes a well layer and a barrier layer, wherein the barrier layer has a larger band gap than the well layer. By adjusting the composition ratio of the semiconductor material in the active layer 112, it is expected to radiate light of different wavelengths.

[0044] The second semiconductor layer 113 is formed below the active layer 112 and may be composed of a group III-V or group II-VI compound semiconductor. The second semiconductor layer 113 may be doped with a second dopant. The second semiconductor layer 113 may be composed of a compound semiconductor having a chemical formula of In x2 Al y2 G a1-x2-y2 N (0≤X2≤1, 0≤Y2≤1, 0≤X2+Y2≤1) semiconductor material, or a material selected from AlGaAs, GaP, GaAs, GaAsP and AlGaInP. When the second dopant is a p-type dopant, such as any one or more of Mg, Zn, Ca, Sr and Ba, the second semiconductor layer 113 doped with the second dopant is a p-type semiconductor layer. The second dopant may also be an n-type dopant, such as any one or more of Si, Ge, Sn, Se and Te. When the second dopant is an n-type dopant, the second semiconductor layer doped with the second dopant is an n-type semiconductor layer. When the first semiconductor layer 111 is an n-type semiconductor layer, the second semiconductor layer 113 is a p-type semiconductor layer; conversely, when the first semiconductor layer 111 is a p-type semiconductor layer, the second semiconductor layer 113 is an n-type semiconductor layer.

[0045] The semiconductor epitaxial stack 110 can provide light with a specific central emission wavelength, such as blue light, green light, red light, purple light, or ultraviolet light. Taking the provision of blue light as an example, the first semiconductor layer 111 is an N-type semiconductor layer, which can provide electrons to the active layer 112 under the action of a power supply. In some embodiments, the N-type semiconductor layer in the first semiconductor layer 111 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 impurity may be one of Si, Ge, Sn, or a combination thereof. In other embodiments, for example, when the epitaxial structure 20 provides red light or infrared light, the first semiconductor layer 111 may be N-type doped AlGaInP, AlGaAs, or other materials belonging to the same system as these two.

[0046] Also refer to Figure 3In an optional embodiment of the present embodiment, the mesa structure in the semiconductor epitaxial stack 110 is formed as a closed mesa hole 114, that is, a hole-shaped structure with an opening only on the upper surface of the semiconductor epitaxial stack 110. The mesa hole 114 sequentially penetrates the second semiconductor layer 113 and the active layer 112 and part of the first semiconductor layer 111 from one side of the second semiconductor layer 113, and is formed in the first semiconductor layer 111. The cross-section of the mesa hole 114 can be any suitable shape such as a circle, an ellipse or a polygon. In this embodiment, a circle is used as an example for explanation. The aperture of the mesa hole 114 is suitable for filling the conductive material to meet good conductivity. At the same time, the aperture of the mesa hole 114 is not too large to ensure sufficient light-emitting area of ​​the light-emitting diode 100. Therefore, the shape and size of the mesa hole 114 can be designed accordingly according to the size of the light-emitting diode 100.

[0047] like Figure 3 As shown, the light-emitting diode 100 also includes an electrode structure 130, which includes a first electrode 131 electrically connected to the first semiconductor layer 111, and a second electrode 132 electrically connected to the second semiconductor layer 113. The first electrode 131 includes a first contact electrode 1313 located at the bottom of the mesa hole 114, a filling electrode 1312 filled into the mesa hole 114, and a second connection electrode 1321 located on the surface of the light-emitting diode 100. The second electrode 132 includes a second contact electrode 1322 located above the second semiconductor layer and a second connection electrode 1321 located on the surface of the light-emitting diode 100. The first contact electrode 1313 can be a single-layer or multi-layer structure with a thickness of about 100 to 500 nm. The first contact electrode 1313 can be formed by stacking one or more metal layers of metals such as chromium, nickel, aluminum, titanium, platinum, gold, palladium, silver, etc. In other embodiments, the first contact electrode 1313 can be one of Ni, GeAu, Au, and a combination thereof. In some embodiments, the first contact electrode 1313 is forming an alloy at the bottom of the mesa hole 114 , thereby forming a good ohmic contact with the first semiconductor layer 111 .

[0048] The second contact electrode 1322 may be made of a transparent conductive material or a metal material, and may be adaptively selected according to the doping condition of the surface layer of the second semiconductor layer 113 (such as the p-type GaN surface layer). The thickness of the second contact electrode 1322 is approximately 100 to 500 nm. In some embodiments, the second contact electrode 1322 is formed of a transparent conductive material, and the material may include indium tin oxide (ITO), zinc indium oxide (IZO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), tin antimony oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), zinc oxide doped gallium (GZO), indium oxide doped tungsten (IWO) or zinc oxide (ZnO), but the embodiments of the present disclosure are not limited thereto. In some embodiments, the second contact electrode 1322 may be formed by stacking one or more electrode layers of metals such as chromium, nickel, aluminum, titanium, platinum, gold, palladium, silver, etc. In other embodiments, the second contact electrode 1322 may be one of Au, BeAu, ZnAu and a combination thereof.

[0049] Likewise Figure 3 As shown, an insulating protective layer 120 is also formed on the surface of the light emitting diode 100. The insulating protective layer 120 is formed on the first surface side of the semiconductor epitaxial stack 110, that is, on the side of the second semiconductor layer 113 of the semiconductor epitaxial stack. Specifically, the surface of the second semiconductor layer 113 is covered while covering the sidewalls of the mesa hole 114 and the sidewalls of the semiconductor epitaxial stack 110. At the same time, the insulating protective layer 120 exposes the first contact electrode 1313 and the second contact electrode 1322, and the upper surface of the second contact electrode 1322 is flush with the upper surface of the insulating protective layer 120. The insulating protective layer 120 can be a single-layer structure or a multi-layer structure, and its thickness is about 0.1 μm to 5 μm, so as to achieve a good insulation effect, prevent the first semiconductor layer and the second semiconductor layer from being connected, and prevent the influence of external water vapor, impurities, etc. on the semiconductor epitaxial stack. Optionally, the insulating protective layer 120 can be an inorganic material, such as silica gel, or a dielectric material such as an electrical insulating material such as aluminum oxide, silicon nitride, silicon oxide, titanium oxide, or magnesium fluoride. Optionally, the insulating protection layer 120 may also be silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate or a combination thereof, and the combination thereof may be, for example, a Bragg reflector (DBR) formed by repeatedly stacking two materials with different refractive indices.

[0050] Refer again Figure 3The filling electrode 1312 of the first electrode 131 is located in the mesa hole 114 and connected to the first contact electrode 1313. At the same time, due to the existence of the insulating protection layer 120, the insulation from the second semiconductor layer 113 and the active layer 112 is achieved. The filling electrode 1312 fully fills and fills the mesa hole 114, and the height difference between the upper surface of the filling electrode 1312 and the upper surface of the light-emitting diode 100 is 0, that is, the upper surface of the filling electrode 1312 is flush with the upper surface of the light-emitting diode 100, specifically, flush with the upper surface of the insulating protection layer 120. The filling electrode 1312 can be a metal material layer, such as any one or more of Cu, Al, Au, etc.; it can also be other conductive materials, such as conductive glue, etc.

[0051] In an alternative embodiment of this embodiment, if Figure 4 As shown, the mesa structure in the semiconductor epitaxial stack 110 is formed as an open mesa 115, that is, the mesa 115 is an open structure on the surface side and at least one side wall of the semiconductor epitaxial stack 110. At this time, the insulating protection layer 120 covers the surface of the second semiconductor layer 113 and covers the surface and side wall of the mesa 115 and the side wall of the semiconductor epitaxial stack 110. At the same time, the insulating protection layer 120 exposes the first contact electrode 1313 and the second contact electrode 1322.

[0052] Also refer to Figure 4 , the filling electrode 1312 of the first electrode 131 is formed above the mesa 115, connected to the first contact electrode 1313, and at the same time, due to the existence of the insulating protection layer 120, the insulation from the second semiconductor layer 113 and the active layer 112 is achieved. The filling electrode 1312 fills the space above the mesa 115 from the surface of the insulating protection layer 120 above the mesa 115 until the upper surface of the filling electrode 1312 is flush with the upper surface of the light-emitting diode 100, specifically, flush with the upper surface of the second semiconductor layer 113, that is, the height difference between the upper surface of the filling electrode 1312 and the upper surface of the light-emitting diode 100 is 0. The filling electrode 1312 can be a metal material layer, such as any one or more of Cu, Al, Au, etc.; it can also be other conductive materials, such as conductive glue, etc.

[0053] In order to further protect the filling electrode 1312 and ensure the insulation of the light-emitting diode 100, an insulating layer 116 is formed on the exposed side wall of the filling electrode 1312. Optionally, the above-mentioned insulating layer 116 can also be formed on the surface of the filling electrode 1312. At this time, an opening exposing the filling electrode is formed in the insulating layer 116 to facilitate the subsequent electrical connection between the connecting electrode and the filling electrode 1312. The insulating layer 116 can also be an inorganic material, such as silica gel, or a dielectric material such as aluminum oxide, silicon nitride, silicon oxide, titanium oxide, or magnesium fluoride. Further, the upper surface of the insulating layer 116 is controlled to be flush with the upper surface of the insulating protection layer 120 above the second semiconductor layer 113. In an optional embodiment, the thickness of the insulating layer 116 above the filling electrode 1312 is less than or equal to 0.5μm, so the depth of the opening exposing the filling electrode 1312 is less than or equal to 0.5μm.

[0054] As described above, the top surfaces of the filling electrode 1312, the insulating protection layer 120 and the second contact electrode 1322 are flush, or within the plane where the top surface of the insulating protection layer 120 is located, the light emitting diode 100 has no concave area, no height difference, and the entire surface is flat. Figure 7 As shown, in the top view of the surface side of the self-insulating protection layer 120, the light emitting diode 100 can form a plurality of filling electrodes 1312 and a plurality of second contact electrodes 1322, and the plurality of filling electrodes 1312 and the plurality of second contact electrodes 1322 are arranged alternately. Figure 3 The first connection electrode 1311 and the second connection electrode 1321 of the light emitting diode 100 are formed above the insulating protection layer 120, the first connection electrode 1311 is connected to the filling electrode 1312, and the second connection electrode 1321 is connected to the second contact electrode 1322. In an optional embodiment, the first connection electrode 1311 and the second connection electrode 1321 can be formed of one or a combination of two or more materials selected from Au, Ag, Al, Pt, Ti, Ni, and Cr, and the first connection electrode 1311 and the second connection electrode 1321 can have the same material composition or different material compositions.

[0055] like Figure 8As shown, the light emitting diode 100 is a regular and flat structure as a whole, the plane where the insulating protection layer 120 is located is a flat structure as a whole, and the first connection electrode 1311 and the second connection electrode 1321 on the surface side thereof also have the same height, and there is no height difference between the two. Therefore, it is beneficial to control the spacing distance between the first connection electrode 1311 and the second connection electrode 1321 to prevent the connection between the two from causing a short circuit; at the same time, the first connection electrode 1311 and the second connection electrode 1321 are both flat structures, and there is no height difference, which is beneficial to increase the surface area of ​​the first connection electrode 1311 and the second connection electrode 1321, and there will be no cracking or breaking caused by the height difference, which is beneficial to improve the subsequent transfer and bonding yield.

[0056] In other optional embodiments of this embodiment, due to process limitations or limitations of existing equipment, sometimes the upper surface of the filling electrode 1312 may not be a regular flat surface, which may cause a small height difference d between the upper surface of the filling electrode 1312 and the upper surface of the light-emitting diode 100. Specifically, the height difference satisfies: -0.5μm≤d<0, or 0<d≤0.5μm. That is, in an optional embodiment, if Figure 4 As shown, due to the formation of the insulating layer 116 above the filling electrode 1312, the surface of the filling electrode 1312 is concave relative to the surface of the insulating layer 116 (or the insulating protection layer 120), that is, -1μm≤d<0; or in another optional embodiment, as Figure 5 As shown, the upper surface of the filling electrode 1312 is lower than the upper surface of the light-emitting diode 100, and the filling electrode 1312 is concave relative to the upper surface of the light-emitting diode 100, at this time -0.5μm≤d<0; or in another optional embodiment, as Figure 6 As shown, the upper surface of the filling electrode 1312 is slightly higher than the upper surface of the light-emitting diode 100, and the filling electrode 1312 is convex relative to the upper surface of the light-emitting diode 100, and at this time 0<d≤0.5μm. Therefore, when forming the connecting electrode 1311, a similar height difference may also exist on the surface of the connecting electrode 1311. However, since -0.5μm≤d<0, or 0<d≤0.5μm, such a height difference can be filled with bonding material during the subsequent bonding of the light-emitting diode 100, that is, the entire surface of the connecting electrode 1311 can still be formed as a bonding surface, increasing the contact area during bonding, and also ensuring the product yield after transfer and bonding.

[0057] In addition, since the height difference of the light emitting diode 100 in the plane where the insulating protection layer is located is -0.5μm≤d≤0.5μm, and further, the height difference is 0, that is, the plane where the insulating protection layer 120 is located is basically or completely flat as a whole, the design flexibility of the first connection electrode 1311 and the second connection electrode 1321 can be increased, and the shape, size, and number of connection electrodes connected in series of the first connection electrode 1311 and the second connection electrode 1321 can be designed according to the final structure, size, and actual needs of the product. Figures 9 to 11 , which shows a schematic diagram of connecting electrodes of several light emitting diodes 100 on a wafer, such as Fig. 9 and Fig.10 As shown, each light emitting diode 100 can be divided as an independent unit. In this case, a first connection electrode 1311 and a second connection electrode 1321 are formed on the filling electrode 1312 and the second contact electrode 1322 of each light emitting diode 100, respectively. Fig. 9 As shown, in an optional embodiment, the cross-sections of the first connection electrode 1311 and the second connection electrode 1321 (i.e., the projection shape on the semiconductor epitaxial stack) are both rectangular structures, and of course, they can also be other polygonal structures, such as diamond, square, pentagon, hexagon, etc. Fig.10 As shown, in another optional embodiment, the cross-sections of the first connection electrode 1311 and the second connection electrode 1321 (i.e., the projected shapes on the semiconductor epitaxial stack) are both circular structures, and of course, they can also be elliptical or other structures similar to a circle or an ellipse. In another optional embodiment, the number and formation positions of the first connection electrodes 1311 and the second connection electrodes 1321 can also be selected according to the number of light-emitting diodes 100 contained in the actual independent unit. That is, a first connection electrode 1311 shared by multiple diodes can be formed above multiple filling electrodes 1312, and a second connection electrode 1321 shared by multiple diodes can be formed above multiple second contact electrodes 1322. As shown in FIG. Fig.11 As shown, a first connection electrode 1311 can be formed to simultaneously cover three filling electrodes 1312, and a second connection electrode 1321 can be formed to simultaneously cover three corresponding second contact electrodes 1322; or a first connection electrode 1311 can be formed to simultaneously cover two filling electrodes 1312, and a second connection electrode 1321 can be formed to simultaneously cover two corresponding second contact electrodes 1322. Fig.11 The depth of the filling color is only used to schematically distinguish the first connection electrode 1311 and the filling electrode 1312 covered by it, and the second connection electrode 1321 and the second contact electrode 1322 covered by it, and has no other meaning.

[0058] Embodiment 2

[0059] This embodiment provides a method for manufacturing a light emitting diode. Fig.12 As shown, the method comprises the following steps:

[0060] S100: forming a semiconductor epitaxial stack, the semiconductor epitaxial stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top, one side of the second semiconductor layer being a first surface;

[0061] like Fig.13 As shown, a semiconductor epitaxial stack is first formed. It can be understood that the semiconductor epitaxial stack can be formed by an epitaxial process on a growth substrate (not shown). The semiconductor epitaxial stack is a first semiconductor layer, an active layer, and a second semiconductor layer from bottom to top. The relevant features of the semiconductor epitaxial stack can refer to the relevant description of the first embodiment, and will not be repeated here.

[0062] S200: etching the semiconductor epitaxial stack from the first surface to form a mesa structure, wherein the mesa structure at least penetrates the second semiconductor layer and the active layer, so that the bottom of the mesa structure is located on the first semiconductor layer;

[0063] like Fig.14 As shown, for example, the second semiconductor layer 113 and the active layer 112 of the semiconductor epitaxial stack 110 are sequentially etched from the second semiconductor layer 113 by an etching process until a portion of the first semiconductor layer 111 is etched to form a closed mesa hole 114. The relevant features of the mesa hole 114 can refer to the relevant description of the first embodiment.

[0064] In another optional embodiment, reference may be made again to Figure 4 The second semiconductor layer 113 and the active layer 112 of the semiconductor epitaxial stack 110 are sequentially etched from the second semiconductor layer 113 by an etching process until a portion of the first semiconductor layer 111 is etched to form an open mesa 115. The relevant features of the mesa 115 can also refer to the relevant description of the first embodiment.

[0065] S300: forming a filling electrode in the mesa structure, wherein the filling electrode is flush with the first surface.

[0066] When the mesa structure is a mesa hole, before forming the filling electrode 1312, Fig.14 As shown in FIG. 1 , firstly, a first contact electrode 1313 is formed on the first semiconductor layer at the bottom of the mesa hole 114, and a second contact electrode 1322 is formed on the second semiconductor layer. Then, as shown in FIG. Fig.15As shown, an insulating protection layer 120 is formed on the first surface side of the semiconductor epitaxial stack (i.e., the surface side of the second semiconductor layer), and the insulating protection layer 120 covers the surface of the second semiconductor layer and the sidewalls of the semiconductor epitaxial stack, and also covers the sidewalls of the mesa hole 114. While covering the surface of the second semiconductor layer and the sidewalls of the mesa hole 114, the insulating protection layer 120 exposes the first contact electrode 1313 and the second contact electrode 1322, and the insulating protection layer 120 can be planarized to make it equal in height to the second contact electrode 1322.

[0067] Afterwards, if Fig.16 As shown, a seed layer 140 is formed on the sidewall and bottom of the mesa hole 114. The seed layer 140 can be a seed layer of metal Ti, Ni, Cr, Cu, Au, Al, etc. For the convenience of process operation, as shown in FIG. Fig.16 As shown, the seed layer 140 can cover the entire surface of the insulating protection layer 120. Fig.17 As shown, a shielding layer 150 such as a photoresist is formed over the seed layer 140 in the region where the filling electrode 1312 is not required to be formed, so as to prevent the formation of a metal layer in the unnecessary region. Fig.17 The structure shown is placed in an electroplating bath for electroplating to grow a metal layer 1312' in the mesa hole 114 until the metal layer 1312' completely fills the mesa hole 114 to form a filling electrode 1312. Fig.18 As shown, the shielding layer 150 is removed, and the height difference between the upper surface of the filling electrode 1312 and the upper surface of the insulating protection layer 120 is -0.5 μm≤d<0, or 0<d≤0.5 μm. For the height difference d, reference may be made to the relevant description of the above embodiment 1.

[0068] Furthermore, after removing the shielding layer 150, the metal layer 1312', the insulating protection layer 120 and the second contact electrode 1322 may be planarized so that the filling electrode 1312 and the insulating protection layer 120 are at the same height, that is, the above d=0. Fig.18 As shown, the upper surfaces of the insulating protection layer 120, the second contact electrode 1322 and the filling electrode 1312 are located in the same plane. Fig.18 The structure shown is a regular and flat structure as a whole, and there is no height difference on the first surface side. Fig.19 As shown, a first connection electrode 1311 and a second connection electrode 1321 are formed on the insulating protection layer 120. Fig.18 The first surface side shown is a flat structure, which is helpful to control the spacing distance between the first connection electrode 1311 and the second connection electrode 1321, and at the same time enables the first connection electrode 1311 and the second connection electrode 1321 to have a sufficiently flat surface to facilitate subsequent transfer and bonding.

[0069] In an optional embodiment, refer again to Figure 4 When the mesa structure is formed into an open mesa 115, the first contact electrode 1313 and the second contact electrode 1322 are first formed on the mesa 115 and on the first surface. An insulating protection layer 120 is formed on the surface and sidewall of the mesa 115 and the first surface, and the insulating protection layer 120 exposes the first contact electrode 1313 on the first semiconductor layer 111 at the mesa 115 and the second contact electrode 1322 on the second semiconductor layer 113. Then, a filling electrode 1312 is formed on the mesa 115 by the same electroplating method. The filling electrode 1312 is formed on the entire mesa 115, and its upper surface is flush with the upper surface of the light emitting diode 100, specifically, flush with the upper surface of the second semiconductor layer 113. Afterwards, in order to further protect the filling electrode 1312 and ensure the insulation of the light-emitting diode 100, an insulating layer 116 is formed on the exposed sidewalls of the filling electrode 1312. Optionally, the insulating layer 116 may also be formed on the surface of the filling electrode 1312. At this time, an opening exposing the filling electrode is formed in the insulating layer 116 to facilitate the subsequent electrical connection between the connecting electrode and the filling electrode 1312. The arrangement of the insulating layer 116 can refer to the relevant description of the first embodiment.

[0070] In an optional embodiment, if Fig. 20 As shown, in the formation Fig.15 After the structure shown, a conductive material with good fluidity and curability, such as a conductive glue 1312", is directly filled in the mesa hole 114. The conductive glue 1312" can evenly fill the mesa hole 114, and it is easy to control its upper surface to be flush with the upper surface of the insulating protection layer 120. Similarly, the conductive glue 1312" can also be directly filled above the mesa 115 to form the above-mentioned filling electrode 1412.

[0071] Embodiment 3

[0072] This embodiment provides a light emitting device, such as Fig.21 As shown, the light emitting device 200 includes a circuit substrate 202, a plurality of light emitters 201 fixed on the circuit substrate 202, and a cover 205 formed above the circuit substrate 202 and the light emitters 201, and the cover 205 can protect the light emitters 201 and the circuit substrate 202 from damage from the outside. A circuit layer 203 is provided in the circuit substrate 202, and a welding layer 204 is formed on the circuit layer 203. In this embodiment, the light emitter 201 is the light emitting diode 100 provided in the first embodiment. The first connection electrode 1311 and the second connection electrode 1321 of the light emitting diode 100 are connected to the welding layer 204, and then connected to the circuit layer 203, so as to realize the lighting or extinguishing of the light emitting diode 100 through the circuit layer 203.

[0073] Since the light-emitting diode 100, especially its filling electrode 1312 and the first connecting electrode 1311 and the second connecting electrode 1321, have the structural characteristics described in Example 1, when it is fixed to the welding layer 204 of the circuit layer 203, good contact can be formed, and there will be no insufficient connection or short circuit due to height difference, thereby improving the yield of the product.

[0074] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A light emitting diode, characterized in that: At least: A semiconductor epitaxial stack, wherein the semiconductor epitaxial stack comprises a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top, and one side of the second semiconductor layer is a first surface of the light-emitting diode; a mesa structure, which at least penetrates the second semiconductor layer and the active layer along the stacking direction of the semiconductor epitaxial stack, and the bottom of the mesa structure is located on the first semiconductor layer; The electrode structure includes a first electrode electrically connected to the first semiconductor layer and a second electrode electrically connected to the second semiconductor layer, wherein the first electrode includes a filling electrode formed in the mesa structure, wherein the height difference between the filling electrode and the first surface is between -0.5 μm and 0.5 μm.

2. The light emitting diode according to claim 1, characterized in that: The fill electrode is flush with the first surface.

3. The light emitting diode according to claim 1, characterized in that: It also includes an insulating protective layer, the mesa structure is formed into a mesa hole, the insulating protective layer covers the first surface and the sidewall of the mesa hole, and the filling electrode fills the mesa hole and is flush with the insulating protective layer on the first surface.

4. The light emitting diode according to claim 1, characterized in that: Also includes The insulating protective layer is an open mesa structure, and the insulating protective layer covers the first surface and the surface and sidewall of the mesa. The filling electrode is located above the mesa and is flush with the insulating protective layer on the first surface side.

5. The light emitting diode according to claim 1, characterized in that: The electrode structure further includes a connecting electrode, which is located on the first surface side, and the cross section of the connecting electrode is any one of polygonal, circular, and elliptical shapes or a combination of multiple shapes.

6. The light emitting diode according to claim 4, characterized in that: The connection electrode includes a first connection electrode connected to the filling electrode and a second connection electrode connected to the second semiconductor layer, and the first connection electrode and the second connection electrode are spaced apart from each other.

7. The light emitting diode according to claim 1, characterized in that: The filling electrode is made of metal material or conductive glue.

8. A light emitting device, characterized in that: It comprises a circuit substrate and a plurality of light emitting elements fixed on the circuit substrate, wherein the light emitting elements comprise the light emitting diodes according to any one of claims 1 to 7.

9. A method for manufacturing a light emitting diode, characterized in that: The following steps are involved: Forming a semiconductor epitaxial stack, the semiconductor epitaxial stack comprising a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top, one side of the second semiconductor layer being a first surface; Etching the semiconductor epitaxial stack from the first surface to form a mesa structure, wherein the mesa structure at least penetrates the second semiconductor layer and the active layer, so that the bottom of the mesa structure is located on the first semiconductor layer; A filling electrode is formed in the mesa structure, and a height difference between the filling electrode and the first surface is between -0.5 μm and 0.5 μm.

10. The method for manufacturing a light emitting diode according to claim 9, characterized in that: The mesa structure is formed as a mesa hole, and forming a filling electrode in the mesa structure further comprises: forming an insulating protective layer on the sidewall of the mesa hole and the first surface; forming a seed layer in the mesa hole, wherein the seed layer covers the insulating protection layer on the side wall of the mesa hole and the bottom of the mesa hole; A metal layer is formed in the mesa hole by electroplating until the metal layer is flush with the insulating protection layer above the first surface to form the filling electrode.

11. The method for manufacturing a light emitting diode according to claim 9, characterized in that: The mesa structure is formed as an open mesa, and forming a filling electrode in the mesa structure further comprises: forming an insulating protective layer above the table top, on the sidewalls and on the first surface; forming a seed layer above the mesa, wherein the seed layer covers the insulating protection layer above the mesa; A metal layer is formed on the mesa by electroplating until the metal layer is flush with the insulating protection layer on the first surface to form the filling electrode.

12. The method for manufacturing a light emitting diode according to claim 9, characterized in that: The mesa structure is formed as a mesa hole, and forming a filling electrode in the mesa hole further comprises: forming an insulating protective layer on the sidewall of the mesa hole and the first surface; Conductive glue is filled in the mesa hole until the conductive glue is flush with the insulating protection layer to form the filled electrode.

13. The method for manufacturing a light emitting diode according to claim 9, characterized in that: The mesa structure is formed as an open mesa, and forming a filling electrode in the mesa structure further comprises: forming an insulating protective layer above the table top, on the sidewalls and on the first surface; Conductive glue is filled above the mesa until the conductive glue is flush with the insulating protection layer above the first surface to form the filling electrode.

14. The method for manufacturing a light emitting diode according to claim 9, characterized in that: After forming a filling electrode in the mesa structure, the method further comprises: forming a first connecting electrode on the first surface side, the first connecting electrode being connected to the filling electrode; A second connection electrode connected to the second semiconductor layer is formed, and the first connection electrode and the second connection electrode are arranged at an interval.

15. The method for manufacturing a light emitting diode according to any one of claims 10 to 13, characterized in that: Before forming a filling electrode in the mesa structure, the method further includes: Forming a first contact electrode at the bottom of the mesa structure, wherein the first contact electrode is connected to the first semiconductor layer and the filling electrode; A second contact electrode is formed on the first surface, wherein the second contact electrode is connected to the second semiconductor layer and is flush with the insulating layer on the first surface.

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