Flexible light emitting diode and method of manufacturing the same

Abstract

The present disclosure provides a flexible light emitting diode and a preparation method thereof, and belongs to the technical field of semiconductors. The flexible light emitting diode comprises a flexible substrate and a light emitting structure. The flexible substrate has opposite bearing surfaces and a bottom surface. The light emitting structure is located on the bearing surface. The light emitting structure comprises a first electrode, a second electrode and an epitaxial structure. The first electrode is located on the surface of the epitaxial structure away from the flexible substrate. The second electrode is located between the epitaxial structure and the flexible substrate. The bottom surface of the flexible substrate has a plurality of first through holes exposing the second electrode. Since the bottom surface of the flexible substrate has a plurality of first through holes exposing the second electrode, when the flexible light emitting diode is connected to an external structure such as a circuit board, the second electrode can be electrically connected to the external structure through the plurality of first through holes on the bottom surface of the flexible substrate, thereby realizing a flexible light emitting diode with a vertical structure.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to a flexible light-emitting diode and its fabrication method. Background Technology

[0002] Light-emitting diodes (LEDs) are highly influential new products in the optoelectronics industry. They are characterized by their small size, long lifespan, rich and colorful colors, and low energy consumption, and are widely used in display devices.

[0003] A light-emitting diode (LED) typically consists of a substrate and a light-emitting structure located on the substrate. In vertical LED structures, a metal substrate is usually used, and one of the electrodes is placed on the metal substrate, taking advantage of its conductivity.

[0004] With the development of technology, flexible LEDs have emerged, which can be easily applied to various flexible display devices. The substrate of flexible LEDs is flexible, but the materials used to make these flexible substrates are usually insulating. This means that flexible LEDs can usually only be used in a top-mounted structure and cannot be used in a vertical structure. Summary of the Invention

[0005] This disclosure provides a flexible light-emitting diode and its fabrication method, enabling the flexible light-emitting diode to adopt a vertical structure. The technical solution is as follows:

[0006] On one hand, this disclosure provides a flexible light-emitting diode, which includes a flexible substrate and a light-emitting structure. The flexible substrate has a supporting surface and a bottom surface, and the light-emitting structure is located on the supporting surface. The light-emitting structure includes a first electrode, a second electrode, and an epitaxial structure. The first electrode is located on the surface of the epitaxial structure away from the flexible substrate, and the second electrode is located between the epitaxial structure and the flexible substrate. The bottom surface of the flexible substrate has a plurality of first through holes exposing the second electrode.

[0007] Optionally, the orthographic projection of the second electrode onto the bearing surface is located outside the orthographic projection of the epitaxial structure onto the bearing surface.

[0008] Optionally, the second electrode includes a first metal layer and a second metal layer, the second metal layer being located on the bearing surface, the first metal layer being located on the surface of the epitaxial structure near the flexible substrate, and the first metal layer being bonded to the second metal layer.

[0009] Optionally, the epitaxial structure and the first metal layer are projected onto the bearing surface, and the side of the second metal layer away from the flexible substrate includes a main region and an edge region located on at least one side of the main region, the main region being the same as the first metal layer; the second electrode further includes a plurality of first conductive blocks, the plurality of first conductive blocks being located in the edge region and connected to the second metal layer.

[0010] Optionally, the thickness of the first conductive block is the same as that of the first metal layer, and the material of the first conductive block is the same as that of the first metal layer.

[0011] Optionally, the first electrode includes an AuGe layer, wherein the germanium content of the AuGe layer is 5-10%.

[0012] On the other hand, this disclosure also provides a method for fabricating a flexible light-emitting diode, the method comprising:

[0013] A flexible substrate is provided, the flexible substrate having a supporting surface and a bottom surface opposite each other;

[0014] A light-emitting structure is formed on the flexible substrate, the light-emitting structure is located on the support surface, the light-emitting structure includes a first electrode, a second electrode and an epitaxial structure, the first electrode is located on the surface of the epitaxial structure away from the flexible substrate, and the second electrode is located between the epitaxial structure and the flexible substrate;

[0015] A plurality of first through holes are formed on the bottom surface of the flexible substrate to expose the second electrode.

[0016] Optionally, forming the light-emitting structure on the flexible substrate includes:

[0017] Provide a growth substrate;

[0018] Epitaxial growth is performed on the growth substrate to form an epitaxial structure;

[0019] A first metal layer is formed on the side of the epitaxial structure away from the growth substrate, and a second metal layer is formed on the bearing surface of the flexible substrate;

[0020] The first metal layer and the second metal layer are bonded together to form the second electrode;

[0021] Remove the growth substrate;

[0022] The first electrode is formed on the side of the epitaxial structure away from the flexible substrate.

[0023] Optionally, before removing the growth substrate, the method further includes:

[0024] Provide a temporary substrate;

[0025] The bottom surface of the flexible substrate is bonded to the temporary substrate.

[0026] Optionally, after forming the first electrode on the side of the epitaxial structure away from the flexible substrate, the method further includes:

[0027] The epitaxial structure is etched to form a groove that exposes the first metal layer;

[0028] The first metal layer portion located within the groove is removed to form a plurality of first conductive blocks on the side of the second metal layer away from the flexible substrate.

[0029] The beneficial effects of the technical solutions provided in this disclosure include at least the following:

[0030] A light-emitting structure is formed by setting a light-emitting structure on the bearing surface of a flexible substrate. The light-emitting structure includes a first electrode, a second electrode, and an epitaxial structure. The two electrodes are located on opposite sides of the epitaxial structure. The first electrode is located on the surface of the epitaxial structure furthest from the flexible substrate, and the second electrode is located between the epitaxial structure and the flexible substrate, forming a vertical structure. Since the bottom surface of the flexible substrate has multiple first through-holes exposing the second electrode, when connecting the flexible light-emitting diode to external structures such as circuit boards, the second electrode can be electrically connected to the external structure via these multiple first through-holes on the bottom surface of the flexible substrate, thus realizing a vertically structured flexible light-emitting diode. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a flexible light-emitting diode provided in an embodiment of this disclosure;

[0033] Figure 2 yes Figure 1 Top view;

[0034] Figure 3 This is a flowchart illustrating a method for fabricating a flexible light-emitting diode according to an embodiment of this disclosure;

[0035] Figure 4 This is a flowchart of another method for fabricating a flexible light-emitting diode provided in this embodiment;

[0036] Figure 5This is a schematic diagram illustrating the fabrication process of a flexible light-emitting diode according to an embodiment of this disclosure;

[0037] Figure 6 This is a schematic diagram illustrating the fabrication process of a flexible light-emitting diode according to an embodiment of this disclosure;

[0038] Figure 7 This is a schematic diagram illustrating the fabrication process of a flexible light-emitting diode according to an embodiment of this disclosure;

[0039] Figure 8 This is a schematic diagram illustrating the fabrication process of a flexible light-emitting diode according to an embodiment of this disclosure;

[0040] Figure 9 This is a schematic diagram of the fabrication process of a flexible light-emitting diode provided in an embodiment of this disclosure. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0042] Figure 1 This is a schematic diagram of the structure of a flexible light-emitting diode provided in an embodiment of this disclosure. Figure 1 As shown, the flexible light-emitting diode includes a flexible substrate 10 and a light-emitting structure 20. The flexible substrate 10 has a supporting surface and a bottom surface, with the light-emitting structure 20 located on the supporting surface. The light-emitting structure 20 includes a first electrode 21, a second electrode 22, and an epitaxial structure 23. The first electrode 21 is located on the surface of the epitaxial structure 23 away from the flexible substrate 10, and the second electrode 22 is located between the epitaxial structure 23 and the flexible substrate 10. The bottom surface of the flexible substrate 10 has multiple first through-holes 10a exposing the second electrode 22.

[0043] For example, the flexible substrate 10 can be a PI (Polyimide) substrate. PI substrates can withstand high temperatures of around 400°C and remain stable during long-term use at -200°C to 300°C, exhibiting high insulation properties. The dielectric loss is low, only 0.004 to 0.007.

[0044] A light-emitting structure 20 is formed on the bearing surface of a flexible substrate 10. The light-emitting structure 20 includes a first electrode 21, a second electrode 22, and an epitaxial structure 23. The two electrodes are located on opposite sides of the epitaxial structure 23. The first electrode 21 is located on the surface of the epitaxial structure 23 away from the flexible substrate 10, and the second electrode 22 is located between the epitaxial structure 23 and the flexible substrate 10, forming a vertical structure. Since the bottom surface of the flexible substrate 10 has multiple first through holes 10a exposing the second electrode 22, when the flexible light-emitting diode is connected to an external structure such as a circuit board, the second electrode 22 can be electrically connected to the external structure through the multiple first through holes 10a on the bottom surface of the flexible substrate 10, thereby realizing a flexible light-emitting diode with a vertical structure.

[0045] For example, when mounting the flexible LED onto a circuit board, it can be connected using conductive silver paste. The circuit board can be a printed circuit board or a flexible circuit board. The conductive silver paste can be applied to the bottom surface of the flexible substrate 10 and fill the first through-hole 10a, connecting the conductive silver paste to the circuit board and the second electrode 22. Of course, other materials capable of connection can also be used, not limited to conductive silver paste; for example, solder could also be used.

[0046] As an example, a plurality of first vias 10a are arrayed on the flexible substrate 10, with a spacing of 100µm between adjacent first vias 10a and a diameter of 20µm for each first via 10a.

[0047] like Figure 1 As shown, the orthographic projection of the second electrode 22 onto the bearing surface is located outside the orthographic projection of the epitaxial structure 23 onto the bearing surface.

[0048] In other words, the second electrode 22 extends laterally relative to the epitaxial structure 23. This allows for electrical connection of the flexible LED via a metal wire from the side of the epitaxial structure 23. For example, when fixing the flexible LED to a circuit board, if no circuit structure is pre-set at the desired location, the conductive silver paste between the flexible substrate 10 and the circuit board only serves a fixing function. The portion of the second electrode 22 extending laterally relative to the epitaxial structure 23 can then be connected to the circuit structure on the circuit board via a wire. Different flexible LEDs can also be connected via wires to link the portions of the second electrode 22 extending laterally relative to the epitaxial structure 23, thus achieving a common polarity connection.

[0049] like Figure 1As shown, the second electrode 22 includes a first metal layer 221 and a second metal layer 222. The second metal layer 222 is located on the bearing surface, and the first metal layer 221 is located on the surface of the epitaxial structure 23 near the flexible substrate 10. The first metal layer 221 and the second metal layer 222 are bonded together.

[0050] The epitaxial structure 23 of the flexible light-emitting diode is typically formed on a common substrate, such as a GaAs substrate. After fabrication, a substrate transfer is performed, transferring the structure to the flexible substrate 10. Here, the epitaxial structure 23 is bonded to the flexible substrate 10 via a first metal layer 221 and a second metal layer 222. The bonded first metal layer 221 and second metal layer 222 can also serve as the second electrode 22.

[0051] like Figure 1 As shown, the epitaxial structure 23 and the first metal layer 221 coincide in orthographic projection on the bearing surface. The side of the second metal layer 222 away from the flexible substrate includes a main region and an edge region located on at least one side of the main region, the main region coinciding with the first metal layer 221. Figure 2 yes Figure 1 Top view, combined Figure 1 and Figure 2 As shown, the second electrode 22 also includes a plurality of first conductive blocks 223, which are located in the edge region. The plurality of first conductive blocks 223 are connected to the second metal layer 222.

[0052] The first metal layer 221 and the second metal layer 222 are of different sizes, with the second metal layer 222 having a larger area. The second metal layer 222 extends beyond the edge of the first metal layer 221. Multiple first conductive blocks 223 are disposed on the second metal layer 222 to facilitate soldering with wires. The multiple first conductive blocks 223 can make the current more uniform and facilitate the lateral spread of the current within the second metal layer 222.

[0053] In some examples, the thickness of the first conductive block 223 is the same as that of the first metal layer 221, and the material of the first conductive block 223 is the same as that of the first metal layer 221.

[0054] Since the thickness and material of the first conductive block 223 are the same as those of the first metal layer 221, the first conductive block 223 and the first metal layer 221 can be manufactured in the same process using the same metal layer, which helps to save on processes. For example, a single metal layer can be used to form the first metal layer 221 and multiple first conductive blocks 223 through a patterning process.

[0055] In the embodiments of this application, the first metal layer 221, the second metal layer 222, and the metal layer used to fabricate the first conductive block 223 and the first metal layer 221 can all be single-layer structures or multi-layer structures. A single-layer structure includes only one film layer formed by a single metal or alloy, while a multi-layer structure includes a structure formed by stacking multiple film layers formed by a single metal or alloy. The materials of different film layers can be the same or different.

[0056] For example, the first metal layer 221 includes a stacked Cr layer, Ti layer, Pt layer and Au layer, wherein the Cr layer is close to the epitaxial structure 23. The thicknesses of the Cr layer, Ti layer, Pt layer and Au layer can be 50 nm, 50 nm, 0.3 µm and 1 µm, respectively.

[0057] The second metal layer 222 includes a stacked Cr layer, Ti layer, and Au layer, wherein the Cr layer is close to the flexible substrate 10. The thicknesses of the Cr layer, Ti layer, and Au layer can be 50 nm, 0.2 µm, and 1 µm, respectively.

[0058] like Figure 1 As shown, the light-emitting structure 20 may further include an insulating layer 25 and a plurality of second conductive blocks 26. The insulating layer 25 is located between the epitaxial structure 23 and the first metal layer 221. The insulating layer 25 has a plurality of second through-holes 25a exposing the epitaxial structure 23. The plurality of second conductive blocks 26 are located in the plurality of second through-holes 25a and are electrically connected to the epitaxial structure 23 and the first metal layer 221. The second conductive blocks 26 are used to form ohmic contacts with the epitaxial structure 23.

[0059] As an example, the insulating layer 25 can be a SiOF layer with a refractive index of 1.45~1.50. Multiple second vias 25a are arrayed, with a spacing of 25μm~30μm between adjacent second vias 25a and a diameter of 7μm for each second via 25a.

[0060] In some examples, the second conductive block 26 can be a multilayer structure, including Au layer, AuZn layer and Au layer stacked in sequence, with thicknesses of 50nm, 200nm and 400nm respectively, wherein the 50nm thick Au layer is close to the epitaxial structure 23.

[0061] like Figure 1As shown, the epitaxial structure 23 includes, in sequence, a p-type GaP ohmic contact layer 240, a p-type AlInP confinement layer 239, a first AlGaInP waveguide layer 238, an active layer 237, a second AlGaInP waveguide layer 236, an n-type AlInP confinement layer 235, an n-type AlGaInP window layer 234, an n-type AlGaInP current spreading layer 233, an n-type AlGaInP roughening layer 232, and an n-type GaAs ohmic contact layer 231. The p-type GaP ohmic contact layer 240 forms an ohmic contact with the second conductive block 26. The n-type GaAs ohmic contact layer 231 is located at the center of the surface of the n-type AlGaInP roughening layer 232 away from the p-type GaP ohmic contact layer 240. The first electrode 21 is located on the surface of the n-type GaAs ohmic contact layer 231 away from the n-type AlGaInP roughening layer 232, forming an ohmic contact with the n-type GaAs ohmic contact layer 231.

[0062] The n-type GaAs ohmic contact layer 231 only covers a portion of the surface of the n-type AlGaInP roughening layer 232 that is away from the p-type GaP ohmic contact layer 240. The area of ​​the n-type AlGaInP roughening layer 232 that is away from the p-type GaP ohmic contact layer 240 that is not covered by the n-type GaAs ohmic contact layer 231 is roughened to form uniformly distributed pyramid-shaped protrusions, which is beneficial to improving the light extraction efficiency of the flexible light-emitting diode.

[0063] Optionally, the first electrode 21 includes an AuGe layer with a Ge content of 5% to 10%. Setting the Ge content in the AuGe layer to 5% to 10% can lower the annealing temperature of the AuGe layer, making the annealing temperature between 250°C and 270°C. This avoids the adverse effects of high temperature on the flexible substrate 10 when annealing the first electrode 21.

[0064] As an example, the first electrode 21 includes an Au layer, an AuGe layer, an Au layer, a Pt layer and an Au layer stacked sequentially on an n-type GaAs ohmic contact layer 231, wherein the thicknesses of each layer are 20 nm, 150 nm, 400 nm, 10 nm and 2.5 µm, respectively.

[0065] like Figure 1 As shown, the flexible light-emitting diode also includes a protective layer 27. The protective layer 27 can be a SiN layer. The protective layer 27 covers the side surface of the epitaxial structure 23 and a portion of the surface away from the flexible substrate 10, exposing a portion of the first electrode 21 and the n-type AlGaInP roughened layer 232.

[0066] Figure 3 This is a flowchart illustrating a method for fabricating a flexible light-emitting diode (LED) according to an embodiment of this disclosure. This method is used to fabricate... Figure 1The flexible light-emitting diode shown is an example. Figure 3 As shown, the method includes:

[0067] In step S11, a flexible substrate 10 is provided.

[0068] The flexible substrate 10 has a supporting surface and a bottom surface.

[0069] In step S12, a light-emitting structure 20 is formed on the flexible substrate 10.

[0070] The light-emitting structure 20 is located on the carrier surface. The light-emitting structure 20 includes a first electrode 21, a second electrode 22 and an epitaxial structure 23. The first electrode 21 is located on the surface of the epitaxial structure 23 away from the flexible substrate 10, and the second electrode 22 is located between the epitaxial structure 23 and the flexible substrate 10.

[0071] In step S13, a plurality of first through holes 10a are formed on the bottom surface of the flexible substrate 10 to expose the second electrode 22.

[0072] For example, the flexible substrate 10 can be a PI (polyimide) substrate. PI substrates can withstand high temperatures of around 400°C and remain stable during long-term use at -200°C to 300°C, exhibiting high insulation properties. The dielectric loss is low, only 0.004 to 0.007.

[0073] A light-emitting structure 20 is formed on the bearing surface of a flexible substrate 10. The light-emitting structure 20 includes a first electrode 21, a second electrode 22, and an epitaxial structure 23. The two electrodes are located on opposite sides of the epitaxial structure 23. The first electrode 21 is located on the surface of the epitaxial structure 23 away from the flexible substrate 10, and the second electrode 22 is located between the epitaxial structure 23 and the flexible substrate 10, forming a vertical structure. Since the bottom surface of the flexible substrate 10 has multiple first through holes 10a exposing the second electrode 22, when the flexible light-emitting diode is connected to an external structure such as a circuit board, the second electrode 22 can be electrically connected to the external structure through the multiple first through holes 10a on the bottom surface of the flexible substrate 10, thereby realizing a flexible light-emitting diode with a vertical structure.

[0074] Figure 4 This is a flowchart illustrating another method for fabricating a flexible light-emitting diode (LED) according to an embodiment of this disclosure. This method is used to fabricate... Figure 1 The flexible light-emitting diode shown. Figures 5-9 This is a schematic diagram illustrating the fabrication process of a flexible light-emitting diode according to an embodiment of this disclosure. The following is combined with... Figures 5-9 right Figure 4 The method shown will be explained in detail. For example... Figure 4 As shown, the method includes:

[0075] In step S21, a growth substrate 31 is provided.

[0076] For example, the growth substrate 31 can be a GaAs substrate, which facilitates subsequent removal.

[0077] In step S22, epitaxial growth is performed on the growth substrate to form an epitaxial structure 23.

[0078] During the epitaxial growth process, GaInP cutoff layer 230, n-type GaAs ohmic contact layer 231, n-type AlGaInP roughening layer 232, n-type AlGaInP current spreading layer 233, n-type AlGaInP window layer 234, n-type AlInP confinement layer 235, second AlGaInP waveguide layer 236, active layer 237, first AlGaInP waveguide layer 238, p-type AlInP confinement layer 239 and p-type GaP ohmic contact layer 240 can be formed sequentially on the growth substrate 31.

[0079] The epitaxial structure 23 comprises, in sequence, a p-type GaP ohmic contact layer 240, a p-type AlInP confinement layer 239, a first AlGaInP waveguide layer 238, an active layer 237, a second AlGaInP waveguide layer 236, an n-type AlInP confinement layer 235, an n-type AlGaInP window layer 234, an n-type AlGaInP current spreading layer 233, an n-type AlGaInP roughening layer 232, and an n-type GaAs ohmic contact layer 231. In subsequent processes, after removing the growth substrate 31, the GaInP cutoff layer 230 is also removed.

[0080] After epitaxial growth is completed, the epitaxial structure can be cleaned.

[0081] In step S23, an insulating layer 25 is formed on the p-type GaP ohmic contact layer 240.

[0082] The insulating layer 25 may have multiple second vias 25a exposing the p-type GaP ohmic contact layer 240, and the multiple second vias 25a are distributed in an array. The spacing between adjacent second vias 25a is 25μm to 30μm, and the diameter of the second via 25a is 7μm.

[0083] For example, the insulating layer 25 can be a SiOF layer. Specifically, SiO2 can be deposited on the surface of the p-type GaP ohmic contact layer 240, and CF4 can be introduced into the reaction chamber during the deposition process to form a SiOF layer. Then, the insulating layer 25 is etched to form a plurality of second vias 25a.

[0084] In step S24, a plurality of second conductive blocks 26 are formed in a plurality of second through holes 25a.

[0085] The second conductive block 26 can be filled in multiple second vias 25a by vapor deposition. The second conductive block 26 can be a multilayer structure, including Au layer, AuZn layer and Au layer stacked sequentially, with thicknesses of 50nm, 200nm and 400nm respectively, wherein the 50nm thick Au layer is close to the epitaxial structure 23.

[0086] After the vapor deposition is completed, annealing can be performed at a temperature of 480°C to form an ohmic contact between the second conductive block 26 and the p-type GaP ohmic contact layer 240.

[0087] In step S25, a first metal layer 221 is formed on the side of the epitaxial structure 23 away from the growth substrate 31.

[0088] The first metal layer 221 can be formed on the side of the epitaxial structure 23 away from the growth substrate 31 by vapor deposition. The first metal layer 221 is connected to the second conductive block 26 in the second via 25a.

[0089] For example, the first metal layer 221 includes a stacked Cr layer, Ti layer, Pt layer and Au layer, wherein the Cr layer is close to the epitaxial structure 23. The thicknesses of the Cr layer, Ti layer, Pt layer and Au layer can be 50 nm, 50 nm, 0.3 µm and 1 µm, respectively.

[0090] The structure after the formation of the first metal layer 221 can be referred to Figure 5 As shown.

[0091] In step S26, a second metal layer 222 is formed on the bearing surface of the flexible substrate 10.

[0092] For example, the flexible substrate 10 can be a PI substrate. The second metal layer 222 can be formed on the bearing surface of the flexible substrate 10 by vapor deposition.

[0093] For example, the second metal layer 222 includes a stacked Cr layer, Ti layer and Au layer, wherein the Cr layer is close to the flexible substrate 10. The thicknesses of the Cr layer, Ti layer and Au layer can be 50 nm, 0.2 µm and 1 µm, respectively.

[0094] In step S27, the first metal layer 221 and the second metal layer 222 are bonded to form the second electrode 22.

[0095] During bonding, the product can be placed in a bonding machine, and bonding can be performed at a bonding temperature of 320℃ and a pressure of 10000Kg.

[0096] In step S28, a temporary substrate 32 is provided, and the bottom surface of the flexible substrate 10 is bonded to the temporary substrate 32.

[0097] The temporary substrate 32 is a rigid substrate, such as a glass substrate. The flexible substrate 10 is relatively soft. The flexible substrate 10 is bonded to the rigid temporary substrate 32, and the temporary substrate 32 provides support, which is beneficial for subsequent processes.

[0098] During bonding, a layer of photoresist can be coated on the temporary substrate 32, and then the bottom surface of the flexible substrate 10 can be bonded to the photoresist at room temperature and a pressure of 2000Kg.

[0099] In step S29, the growth substrate 31 is removed.

[0100] Specifically, the product can be placed in a mixed solution of ammonia and hydrogen peroxide for 30-50 minutes to remove the GaAs substrate. Then, the product is placed in a mixed solution of hydrochloric acid and phosphoric acid to remove the GaInP stop layer 230, exposing the n-type GaAs ohmic contact layer 231.

[0101] Subsequently, the n-type GaAs ohmic contact layer 231 can be etched to expose a portion of the n-type AlGaInP roughened layer 232 away from the p-type GaP ohmic contact layer 240, facilitating subsequent roughening of the n-type AlGaInP roughened layer 232. Its structure can be referenced... Figure 6 As shown. When etching the n-type GaAs ohmic contact layer 231, for example, a mixed solution of phosphoric acid and hydrogen peroxide can be used for etching.

[0102] In step S30, a first electrode 21 is formed on the side of the epitaxial structure 23 away from the flexible substrate 10.

[0103] Specifically, the first electrode 21 can be formed on the surface of the n-type GaAs ohmic contact layer 231 away from the n-type AlGaInP roughening layer 232 by vapor deposition. After vapor deposition, annealing can be performed at 260°C to form an ohmic contact between the first electrode 21 and the n-type GaAs ohmic contact layer 231.

[0104] As an example, the first electrode 21 includes an Au layer, an AuGe layer, an Au layer, a Pt layer and an Au layer stacked sequentially on an n-type GaAs ohmic contact layer 231, wherein the thicknesses of each layer are 20 nm, 150 nm, 400 nm, 10 nm and 2.5 µm, respectively.

[0105] After the first electrode 21 is formed, photolithography can be used to process the epitaxial structure 23 to define the light-emitting area and the size of the cutting path, which facilitates the cutting of multiple independent flexible light-emitting diodes in subsequent processes.

[0106] In step S31, the n-type AlGaInP roughening layer 232 is roughened.

[0107] By roughening the surface of the n-type AlGaInP roughened layer 232, which is far from the p-type GaP ohmic contact layer 240, uniformly distributed pyramid-shaped protrusions are formed, which is beneficial to improving the light extraction efficiency of the flexible light-emitting diode.

[0108] During the roughening process, the roughening solution can be a mixed solution of ammonium fluoride, potassium iodate, potassium sulfate, ammonium acetate, and glycerol. In the roughening solution, the concentration of ammonium fluoride is 45%–55%, the concentration of potassium iodate is 5%–10%, the concentration of potassium sulfate is 10%–15%, the concentration of ammonium acetate is 2%–3%, the concentration of glycerol is 2%–3%, and the remainder is water.

[0109] In step S32, a protective layer 27 is formed on the surface of the epitaxial structure 23.

[0110] For example, the protective layer 27 can be a SiN layer. The protective layer 27 covers the sides of the epitaxial structure 23 and a portion of the surface away from the flexible substrate 10, exposing a portion of the first electrode 21 and the n-type AlGaInP roughened layer 232. The structure after forming the protective layer 27 can be referred to... Figure 7 As shown.

[0111] In step S33, the epitaxial structure 23 is etched to form a groove 23a that exposes the first metal layer 221.

[0112] like Figure 8 As shown, by forming a groove 23a, the orthographic projection of the second electrode 22 on the bearing surface is located outside the orthographic projection of the epitaxial structure 23 on the bearing surface, that is, the second electrode 22 extends laterally relative to the epitaxial structure 23.

[0113] In step S34, a portion of the first metal layer 221 located in the groove is removed to form a plurality of first conductive blocks 223 on the side of the second metal layer 222 away from the flexible substrate 10.

[0114] Specifically, this is achieved through a patterning process, where a single metal layer is fabricated into a first metal layer 221 and multiple first conductive blocks 223 in a single process. The structure after forming the first conductive blocks 223 can be referenced. Figure 9

[0115] In step S35, a plurality of first through holes 10a are formed on the bottom surface of the flexible substrate 10 to expose the second electrode 22.

[0116] First, a layer of photoresist can be formed on the surface of the light-emitting structure 20 as a protective layer. Then, an etching solution is used to etch the surface, separating the flexible substrate 10 from the temporary substrate 32. Next, a photolithography process is used to process the bottom surface of the flexible substrate 10, creating multiple first through-holes 10a to expose the second electrode 22. The structure after forming the first through-holes 10a can be referenced. Figure 1 As shown.

[0117] The flexible LEDs can then be annealed at a temperature of 200°C to further improve the adhesion between the first metal layer 221 and the second metal layer 222. After annealing, they can be cut to form multiple flexible LEDs.

[0118] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes.

Claims

1. A flexible light-emitting diode, characterized in that, The device includes a flexible substrate (10) and a light-emitting structure (20). The flexible substrate (10) has a supporting surface and a bottom surface. The light-emitting structure (20) is located on the supporting surface. The light-emitting structure (20) includes a first electrode (21), a second electrode (22), and an epitaxial structure (23). The first electrode (21) is located on the surface of the epitaxial structure (23) away from the flexible substrate (10). The second electrode (22) is located between the epitaxial structure (23) and the flexible substrate (10). The bottom surface of the flexible substrate (10) has a plurality of first through holes (10a) exposing the second electrode (22).

2. The flexible light-emitting diode according to claim 1, characterized in that, The second electrode (22) is located outside the orthographic projection of the epitaxial structure (23) on the bearing surface in the orthographic projection of the bearing surface.

3. The flexible light-emitting diode according to claim 2, characterized in that, The second electrode (22) includes a first metal layer (221) and a second metal layer (222). The second metal layer (222) is located on the bearing surface, and the first metal layer (221) is located on the surface of the epitaxial structure (23) near the flexible substrate (10). The first metal layer (221) and the second metal layer (222) are bonded together.

4. The flexible light-emitting diode according to claim 3, characterized in that, The epitaxial structure (23) and the first metal layer (221) coincide in the orthographic projection of the bearing surface. The side of the second metal layer (222) away from the flexible substrate includes a main region and an edge region located on at least one side of the main region. The main region coincides with the first metal layer (221). The second electrode also includes a plurality of first conductive blocks (223), which are located in the edge region and connected to the second metal layer (222).

5. The flexible light-emitting diode according to claim 4, characterized in that, The thickness of the first conductive block (223) is the same as that of the first metal layer (221), and the material of the first conductive block (223) is the same as that of the first metal layer (221).

6. The flexible light-emitting diode according to any one of claims 1 to 5, characterized in that, The first electrode (21) includes an AuGe layer, wherein the germanium content of the AuGe layer is 5% to 10%.

7. A method for fabricating a flexible light-emitting diode, characterized in that, include: A flexible substrate (10) is provided, the flexible substrate (10) having a supporting surface and a bottom surface opposite each other; A light-emitting structure (20) is formed on the flexible substrate (10). The light-emitting structure (20) is located on the bearing surface. The light-emitting structure (20) includes a first electrode (21), a second electrode (22), and an epitaxial structure (23). The first electrode (21) is located on the surface of the epitaxial structure (23) away from the flexible substrate (10). The second electrode (22) is located between the epitaxial structure (23) and the flexible substrate (10). A plurality of first through holes (10a) are formed on the bottom surface of the flexible substrate (10) to expose the second electrode (22).

8. The preparation method according to claim 7, characterized in that, The formation of the light-emitting structure (20) on the flexible substrate (10) includes: Provide a growth substrate (31); Epitaxial growth is performed on the growth substrate to form an epitaxial structure (23). A first metal layer (221) is formed on the side of the epitaxial structure (23) away from the growth substrate (31), and a second metal layer (222) is formed on the bearing surface of the flexible substrate. The first metal layer (221) and the second metal layer (222) are bonded together to form the second electrode (22). Remove the growth substrate (31); The first electrode (21) is formed on the side of the epitaxial structure (23) away from the flexible substrate (10).

9. The preparation method according to claim 8, characterized in that, Before removing the growth substrate (31), the method further includes: Provide a temporary substrate (32); The bottom surface of the flexible substrate (10) is bonded to the temporary substrate (32).

10. The preparation method according to claim 8, characterized in that, After forming the first electrode (21) on the side of the epitaxial structure (23) away from the flexible substrate (10), the method further includes: The epitaxial structure (23) is etched to form a groove (23a) that exposes the first metal layer (221). The first metal layer (221) located in the groove is partially removed to form a plurality of first conductive blocks (223) on the side of the second metal layer (222) away from the flexible substrate (10).

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