Spherical LED chip, preparation method thereof and LED chip transfer method

Abstract

The application relates to a spherical LED chip and a preparation method and an LED chip transfer method thereof. The spherical LED chip comprises a spherical epitaxial layer, an electrode and an insulating layer. The spherical epitaxial layer comprises a first semiconductor layer, an active layer wrapped in the first semiconductor layer, and a second semiconductor layer wrapped in the active layer. The electrode comprises a first electrode and a second electrode arranged on one side of the spherical epitaxial layer, the first electrode is electrically connected with the first semiconductor layer, and the second electrode is electrically connected with the second semiconductor layer. The insulating layer comprises a first insulating layer arranged between the first electrode and the second semiconductor layer and the active layer, a second insulating layer arranged on one side of the spherical epitaxial layer, and a third insulating layer arranged on the other side of the spherical epitaxial layer. The electrodes are arranged on one side, so that when the spherical LED chip is placed in a fluid, the electrode side is more likely to keep a downward direction, the spherical LED chip is accurately and massively transferred to a groove of a back plate, and the assembly efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of mass transfer of chips, and more particularly to a spherical LED chip and its fabrication method and LED chip transfer method. Background Technology

[0002] Currently, Micro LED (Micro Light Emitting Diode) technology, also known as LED (Light Emitting Diode) miniaturization and matrixing technology, refers to a high-density, micro-sized LED array integrated on a single chip. For example, each pixel of an LED display can be addressed and individually driven to light up, making it a miniaturized version of an outdoor LED display, reducing pixel distance from millimeters to micrometers. The Micro LED array is fabricated using standard CMOS (Complementary Metal Oxide Semiconductor) integrated circuit manufacturing processes to create the LED display driver circuit. Then, an MOCVD (Metal-organic Chemical Vapor Deposition) machine is used to fabricate the LED array on the integrated circuit, thus realizing a miniaturized display screen—a scaled-down version of an LED display. However, existing mass transfer methods suffer from complex processes and operations, and difficulty in controlling precision, preventing accurate mass production.

[0003] Therefore, how to achieve precise mass transfer of LED chips and improve assembly efficiency is an urgent problem to be solved. Summary of the Invention

[0004] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a spherical LED chip and its preparation method and LED chip transfer method, aiming to solve the problems of complex and low accuracy of LED chip mass transfer operation in the related technologies.

[0005] A spherical LED chip includes a spherical epitaxial layer, electrodes, and an insulating layer; The spherical epitaxial layer includes a first semiconductor layer, an active layer enclosing the first semiconductor layer, and a second semiconductor layer enclosing the active layer. The electrode includes a first electrode and a second electrode disposed on one side of the epitaxial layer of the sphere and insulated from each other. The first electrode passes through the second semiconductor layer and the active layer and is electrically connected to the first semiconductor layer. The second electrode is electrically connected to the second semiconductor layer. The insulating layer includes a first insulating layer disposed between the first electrode and the second semiconductor layer and the active layer, a second insulating layer disposed on one side of the spherical epitaxial layer covering the exposed area of ​​the second semiconductor layer, and a third insulating layer disposed on the other side of the spherical epitaxial layer covering the exposed area of ​​the second semiconductor layer.

[0006] The electrodes of the aforementioned spherical LED chips are all located on one side of the epitaxial layer of the sphere. This increases the probability that the electrode side will remain facing downwards when the spherical LED chip is placed in a fluid, enabling precise and large-scale transfer of the spherical LED chips to the grooves of the backplate and improving the efficiency and accuracy of LED chip transfer.

[0007] Based on the same inventive concept, this application also provides a method for fabricating a spherical LED chip, the method comprising: A first semiconductor layer, forming a first hemisphere, is formed on a first substrate; An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the first hemisphere, and a second semiconductor layer covering the first hemisphere is formed on the active layer. An etching barrier layer is deposited on the surface of the second semiconductor layer; Remove the first substrate and form a second hemisphere first semiconductor layer in the region above the first semiconductor layer of the first hemisphere; An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the second hemisphere, and a second semiconductor layer covering the second hemisphere is formed on the active layer. On the second semiconductor layer of the second hemisphere, the following are formed respectively: a first electrode that passes through the second semiconductor layer and the active layer and is electrically connected to the first semiconductor layer, a second electrode that is electrically connected to the second semiconductor layer, a first insulating layer located between the first electrode and the second semiconductor layer and the active layer, and a second insulating layer that covers the exposed area of ​​the second semiconductor layer. Remove the etch barrier layer and form a third insulating layer on the second semiconductor layer of the first hemisphere.

[0008] In the above-mentioned method for fabricating spherical LED chips, by forming an electrode on one side of the epitaxial layer of the sphere, when the spherical LED chip is placed in a fluid, the electrode side is more likely to remain facing downwards, thereby achieving precise and massive transfer of the spherical LED chip to the groove of the backplate and improving the efficiency and accuracy of LED chip transfer.

[0009] Based on the same inventive concept, this application also provides an LED chip transfer method, comprising: Provides a suspension and spherical LED chips as described above; A backplate is provided, the backplate having a plurality of grooves adapted to the spherical LED chip; The backplate is placed horizontally in the suspension, and the spherical LED chips are dispersed into the suspension. The suspension is controlled to carry the spherical LED chip in a horizontal direction, so that the spherical LED chip is transferred onto the groove.

[0010] The aforementioned LED chip transfer method provides a spherical LED chip with an electrode set on one side of the spherical epitaxial layer. When the spherical LED chip is placed in a fluid, the electrode side is more likely to remain facing downwards, enabling the precise and massive transfer of the spherical LED chip to the groove of the backplate, thereby improving the efficiency and accuracy of LED chip transfer. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of a spherical LED chip provided in an embodiment of the present invention; Figure 2 A schematic diagram of the orthographic projection of the electrodes of a spherical LED chip provided in an embodiment of the present invention; Figure 3 Another orthographic projection schematic diagram of the electrodes of a spherical LED chip provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of an ellipsoidal LED chip provided in an embodiment of the present invention; Figure 5 A schematic diagram of the orthographic projection of the electrodes of an ellipsoidal LED chip provided in an embodiment of the present invention; Figure 6 A basic flowchart of a method for fabricating a spherical LED chip is provided as another optional embodiment of the present invention; Figure 7 A schematic diagram of a process for fabricating a spherical LED chip, provided as another optional embodiment of the present invention; Figure 8 A basic flowchart of a method for fabricating an ellipsoidal LED chip is provided as another optional embodiment of the present invention; Figure 9 A schematic diagram of a process for fabricating an ellipsoidal LED chip, provided as another optional embodiment of the present invention; Figure 10 A basic flowchart of an LED chip transfer method provided in another optional embodiment of the present invention; Figure 11 A schematic diagram of an LED chip transfer method provided in another optional embodiment of the present invention; Figure 12 This is a schematic diagram of another LED chip transfer method provided in another optional embodiment of the present invention.

[0012] Explanation of reference numerals in the attached figures: 10-sphere epitaxial layer, 11-first semiconductor layer, 12-active layer, 13-second semiconductor layer, 14-first electrode, 15-second electrode, 16-first insulating layer, 17-second insulating layer, 18-third insulating layer, 19-first substrate, 20-etch barrier layer, 21-sphere LED chip, 22-backplane, 23-groove, 24-first pad, 25-second pad. Detailed Implementation

[0013] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0015] In related technologies, LED display driver circuits are usually fabricated at the bottom layer using normal CMOS integrated circuit manufacturing processes, and then LED arrays are fabricated on the integrated circuit using an MOCVD machine. However, the mass transfer method suffers from complex processes and operations, and difficulty in controlling precision, making it impossible to achieve accurate mass production. Therefore, this application aims to provide a solution that can solve the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

[0016] This embodiment illustrates a spherical LED chip, comprising a spherical epitaxial layer, electrodes, and an insulating layer. The electrodes are all disposed on one side of the spherical epitaxial layer, increasing the probability that the electrode side will remain downward-facing when the spherical LED chip is placed in a fluid. This enables precise, large-scale transfer of the spherical LED chips to the grooves on the backplane, improving the efficiency and accuracy of LED chip transfer. For ease of understanding, this embodiment will be described below using... Figure 1 The spherical LED chip shown is an example for ease of understanding: Please see Figure 1 As shown, the spherical LED chip includes: 10. Sphere epitaxial layer, electrode and insulating layer; The spherical epitaxial layer 10 includes a first semiconductor layer 11, an active layer 12 enclosing the first semiconductor layer 11, and a second semiconductor layer 13 enclosing the active layer 12. The electrode includes a first electrode 14 and a second electrode 15 disposed on one side of the epitaxial layer 10 of the sphere and insulated from each other. The first electrode 14 passes through the second semiconductor layer 13 and the active layer 12 and is electrically connected to the first semiconductor layer 11. The second electrode 15 is electrically connected to the second semiconductor layer 13. The insulating layer includes a first insulating layer 16 disposed between the first electrode 14 and the second semiconductor layer 13 and the active layer 12, a second insulating layer 17 disposed on one side of the spherical epitaxial layer 10 covering the exposed area of ​​the second semiconductor layer 13, and a third insulating layer 18 disposed on the other side of the spherical epitaxial layer 10 covering the exposed area of ​​the second semiconductor layer 13.

[0017] In this example, the first electrode 14 and the second electrode 15 can be metal electrodes. It should be understood that the first electrode 14 and the second electrode 15 are located on one side of the spherical epitaxial layer 10, so the density on the side containing the electrodes is greater than the density on the side without the electrodes. That is to say, the mass of the spherical LED chip on the side containing the electrodes is greater than the mass on the other side.

[0018] In this example, both the first electrode 14 and the second electrode 15 include magnetic materials, which include at least one of permanent magnet alloys, neodymium iron boron permanent magnet materials, permanent magnet ferrites, rare earth permanent magnet materials, and composite permanent magnet materials. The first electrode 14 has a first magnetic property, and the second electrode 15 has a second magnetic property, and the first and second magnetic properties are different. The second electrode 15 can surround the first electrode 14, that is, the orthographic projection of the second electrode 15 is a ring, not limited to a circular ring, a polygonal ring, or an irregularly shaped ring. The orthographic projection of the second electrode 15 can be a triangular ring, a circular ring, a quadrilateral ring, or other rings. The orthographic projection of the second electrode 15 can also be a non-closed shape. The second electrode 15 can include multiple spaced electrode portions, and the line connecting the centers of the multiple electrode portions forms a closed shape. Furthermore, the orthographic projections of the centers of gravity of the first electrode 14 and the second electrode 15 can be set to coincide, which can better ensure that the first electrode 14 is vertically downward and improve the accuracy of transfer. The materials of the first electrode 14 and the second electrode 15 can be any one or more of Ag, Al, Rh, Cr, Pt, Au, Ti, and Ni, or they can be alloy materials. The first electrode 14 and the second electrode 15 can be single-layer or multi-layer structures. In this embodiment, the first electrode 14 is a columnar electrode, which can be a cylindrical electrode, a triangular prism electrode, a polygonal columnar electrode, or an irregularly shaped columnar electrode, depending on the actual application requirements. In this example, such as Figure 2 As shown, the orthographic projection of the first electrode 14 can be set to a circle, and the orthographic projection of the second electrode 15 can be a triangular ring. Figure 2 (a-1) Alternatively, the orthographic projection of the first electrode 14 can be set to a square, and the orthographic projection of the second electrode 15 can be an annular shape. Figure 2(a-2), or the orthographic projection of the first electrode 14 can be a triangle and the orthographic projection of the second electrode 15 can be a quadrilateral ring ( Figure 2 (a-3).

[0019] In this example, such as Figure 3 As shown, the orthographic projection of the first electrode 14 can also be set to a circle, and the orthographic projection of the second electrode 15 can be a non-closed shape. Figure 3 (b-1) or the first electrode portion is a cuboid, and the second electrode 15 may include two separately disposed electrode portions, that is, the orthographic projection of the first electrode 14 is a rectangle and the orthographic projection of the second electrode 15 may be two separate rectangles ( Figure 3 (b-2).

[0020] In this example, the density of at least one of the first insulating layer 16 and the second insulating layer 17 is greater than the density of the third insulating layer 18. Alternatively, both the first insulating layer 16 and the second insulating layer 17 may be configured to have a density greater than the density of the third insulating layer 18, further ensuring a greater mass on the electrode side of the spherical LED chip. The first insulating layer 16 and the second insulating layer 17 can be made of the same material. For example, the first insulating layer 16 and the second insulating layer 17 can be made of silicon oxide with a density between 2.2 and 2.66, such as 2.3, 2.4, 2.6, or other densities. The third insulating layer 18 can be made of silicon nitride, or silicon oxide with a density between 3.44 and 3.5, such as 3.45, 3.47, 3.48, or other densities.

[0021] In this example, the spherical epitaxial layer 10 is either a spherical epitaxial layer or an ellipsoidal epitaxial layer. It should be understood that in this example, it is sufficient to ensure that the outer contour of the spherical LED chip is spherical or ellipsoidal; therefore, the spherical epitaxial layer 10 can also be an irregularly shaped spherical epitaxial layer. Figure 4 This is a schematic diagram of the structure of an ellipsoidal LED chip provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the spherical epitaxial layer 10 is an ellipsoidal epitaxial layer, and the spherical LED chip is an ellipsoidal LED chip.

[0022] The ellipsoidal LED chip includes: 10. Sphere epitaxial layer, electrode and insulating layer; The spherical epitaxial layer 10 includes a first semiconductor layer 11, an active layer 12 enclosing the first semiconductor layer 11, and a second semiconductor layer 13 enclosing the active layer 12. The electrodes include a first electrode 14 and a second electrode 15 disposed on one side of the spherical epitaxial layer 10 and insulated from each other. The first electrode 14 passes through the second semiconductor layer 13 and the active layer 12 and is electrically connected to the first semiconductor layer 11. The second electrode 15 is electrically connected to the second semiconductor layer 13. The insulating layer includes a first insulating layer 16 disposed between the first electrode 14 and the second semiconductor layer 13 and the active layer 12, a second insulating layer 17 disposed on one side of the spherical epitaxial layer 10 covering the exposed area of ​​the second semiconductor layer 13, and a third insulating layer 18 disposed on the other side of the spherical epitaxial layer 10 covering the exposed area of ​​the second semiconductor layer 13.

[0023] It should be understood that, because the ellipsoidal LED chip is ellipsoidal, and stability increases with a lower center of gravity, it is typically positioned with its major axis horizontal and its minor axis vertical. Therefore, the ellipsoidal LED chip can be divided into two sides along its major axis, with the first electrode 14 and the second electrode 15 located on one side of the spherical epitaxial layer 10. Consequently, the density on the side containing the electrodes is greater than the density on the side without the electrodes. In other words, the mass of the ellipsoidal LED chip on the side containing the electrodes is greater than the mass on the other side.

[0024] In this example, both the first electrode 14 and the second electrode 15 comprise magnetic materials, which include at least one of the following: permanent magnet alloy, neodymium iron boron permanent magnet material, permanent magnet ferrite, rare earth permanent magnet material, and composite permanent magnet material. The first electrode 14 possesses a first magnetic property, and the second electrode 15 possesses a second magnetic property, and the first and second magnetic properties are different. The materials of the first electrode 14 and the second electrode 15 can be any one or more of Ag, Al, Rh, Cr, Pt, Au, Ti, and Ni, or they can be alloy materials.

[0025] The first electrode portion is a cuboid, and the second electrode 15 may include two separately disposed electrode portions, such as... Figure 5 As shown, the orthographic projection of the first electrode 14 is a rectangle, and the orthographic projection of the second electrode 15 can be two separate rectangles. The extension direction of the first electrode 14 is parallel to the minor axis direction of the ellipsoidal LED chip, and the extension direction of the second electrode 15 is parallel to the major axis direction of the ellipsoidal LED chip.

[0026] In this example, the densities of both the first insulating layer 16 and the second insulating layer 17 can be set to be greater than the density of the third insulating layer 18, to ensure that the mass of the spherical LED chip including the electrode side is greater as much as possible. The first insulating layer 16 and the second insulating layer 17 can be made of the same material. For example, the first insulating layer 16 and the second insulating layer 17 can be made of silicon oxide with a density between 2.2 and 2.66, such as a density of 2.3, 2.4, 2.6 or other densities. The third insulating layer 18 can be made of silicon nitride, and can be made of silicon oxide with a density between 3.44 and 3.5, such as a density of 3.45, 3.47, 3.48 or other densities.

[0027] In this example, a current spreading layer may also be provided between the second semiconductor layer 13 and the insulating layer, and an electron blocking layer may be provided between the active layer 12 and the second semiconductor layer 13, depending on actual needs.

[0028] The electrodes of the aforementioned spherical LED chips are all located on one side of the epitaxial layer of the sphere, which increases the probability that the electrode side will remain facing downward when the spherical LED chip is placed in a fluid. Furthermore, the density of at least one of the first and second insulating layers is greater than the density of the third insulating layer, which further increases the probability of keeping the electrode side facing downward. This enables the precise and massive transfer of the spherical LED chips to the grooves of the backplate, improving the efficiency and accuracy of LED chip transfer.

[0029] This embodiment also provides a method for fabricating a spherical LED chip, such as... Figure 6 As shown, Figure 6 This is a basic flowchart of a method for fabricating a spherical LED chip provided in this embodiment. Figure 7 for Figure 6 The method includes a process diagram corresponding to each step, and the method comprises: S201: A first semiconductor layer in the shape of a first hemisphere is formed on a first substrate.

[0030] The formation of a first semiconductor layer 11 with a first hemisphere on a first substrate 19 includes: growing a first semiconductor layer on the first substrate 19, forming a spherical particle on the first semiconductor layer, and using the spherical particle as a mask to etch the first semiconductor layer to obtain the first semiconductor layer 11 with a first hemisphere.

[0031] S202: An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the first hemisphere, and a second semiconductor layer covering the first hemisphere is formed on the active layer.

[0032] An active layer 12 and a second semiconductor layer 13 are sequentially grown on the first semiconductor layer 11 using an MOCVD machine.

[0033] S203: Deposit an etch barrier layer on the surface of the second semiconductor layer.

[0034] The etch barrier layer 20 provides another substrate that conforms to the outer contour of the second semiconductor layer. Specifically, the etch barrier layer 20 may include silicon nitride.

[0035] S204: Remove the first substrate and form the first semiconductor layer of the second hemisphere in the region above the first semiconductor layer of the first hemisphere.

[0036] Specifically, the process involves growing a first semiconductor layer 11 in a region above the first semiconductor layer 11 of the first hemisphere, forming a spherical particle on the first semiconductor layer 11, and using the spherical particle as a mask to etch the first semiconductor layer to obtain the first semiconductor layer 11 of the second hemisphere.

[0037] S205: An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the second hemisphere, and a second semiconductor layer covering the second hemisphere is formed on the active layer.

[0038] The first semiconductor layer 11, the active layer 12, and the second semiconductor layer 13 of the second hemisphere are etched according to the mask with the preset pattern.

[0039] S206: On the second semiconductor layer of the second hemisphere, a first electrode electrically connected to the first semiconductor layer through the second semiconductor layer and the active layer, a second electrode electrically connected to the second semiconductor layer, a first insulating layer located between the first electrode and the second semiconductor layer and the active layer, and a second insulating layer covering the exposed area of ​​the second semiconductor layer are formed respectively.

[0040] It should be understood that the formation of the first electrode hole is also included before the formation of the first electrode 14.

[0041] Specifically, photoresist can be applied based on step S204, and the photoresist can block part of the first semiconductor layer 11, which is equivalent to reserving the position of the first electrode hole. Then, an active layer 12 covering the first semiconductor layer is formed, and a second semiconductor layer 13 covering the second hemisphere of the active layer 12 is formed on the active layer 12. Then, the photoresist is removed, which is equivalent to forming the first electrode hole through the second semiconductor layer and the active layer.

[0042] In another embodiment, based on step S204, the active layer 12 and the second semiconductor layer 13 can be etched to form a first electrode hole through the second semiconductor layer 13 and the active layer 12.

[0043] After forming the first electrode hole, a first insulating layer 16 is deposited on the hole wall of the first electrode hole, and a second insulating layer 17 is deposited covering the exposed area of ​​the second semiconductor layer 13. A first electrode 14 electrically connected to the first semiconductor layer 11 is formed at the first electrode hole, a portion of the second insulating layer 17 is removed to form a second electrode hole, and a second electrode 15 electrically connected to the second semiconductor layer 13 is formed at the second electrode hole.

[0044] S207: Remove the etch barrier layer and form a third insulating layer on the second semiconductor layer above the first semiconductor layer of the first hemisphere.

[0045] The density of at least one of the first insulating layer 16 and the second insulating layer 17 is greater than the density of the third insulating layer 18, thereby increasing the probability of keeping the electrode side facing downwards. To further increase the probability of keeping the electrode side facing downwards, the density of both the first insulating layer 16 and the second insulating layer 17 can be set to be greater than the density of the third insulating layer 18.

[0046] This embodiment also provides a method for fabricating an ellipsoidal LED chip, such as... Figure 8 As shown, Figure 8 This is a basic flowchart of a method for fabricating an ellipsoidal LED chip provided in this embodiment. Figure 9 for Figure 8 The method includes process diagrams for each step, and the method itself includes: S301: A first semiconductor layer in the shape of a first semi-ellipsoid is formed on a first substrate.

[0047] The formation of a first semiconductor layer 11 with a first semi-ellipsoid on a first substrate 19 includes: growing a first semiconductor layer on the first substrate 19, forming a spherical particle on the first semiconductor layer, and using the spherical particle as a mask to etch the first semiconductor layer to obtain the first semiconductor layer 11 with a first semi-ellipsoid.

[0048] S302: An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the first semi-ellipsoid, and a second semiconductor layer covering the first semi-ellipsoid is formed on the active layer.

[0049] An active layer 12 and a second semiconductor layer 13 are sequentially grown on the first semiconductor layer 11 using an MOCVD machine.

[0050] S303: An etch barrier layer is deposited on the surface of the second semiconductor layer.

[0051] The etch barrier layer 20 provides another substrate that conforms to the outer contour of the second semiconductor layer. Specifically, the etch barrier layer 20 may include silicon nitride.

[0052] S304: Remove the first substrate and form a second semi-ellipsoidal first semiconductor layer in the region above the first semiconductor layer of the first semi-ellipsoid.

[0053] Specifically, the process involves growing a first semiconductor layer 11 on a region above the first semiconductor layer 11 of the first semi-ellipsoid, forming a spherical particle on the first semiconductor layer 11, and using the spherical particle as a mask to etch the first semiconductor layer to obtain the first semiconductor layer 11 of the second semi-ellipsoid.

[0054] S305: An active layer covering the first semiconductor layer is formed on the second semi-ellipsoidal first semiconductor layer, and a second semiconductor layer covering the active layer is formed on the active layer.

[0055] The first semiconductor layer 11, the active layer 12, and the second semiconductor layer 13 of the second semi-ellipsoid are etched according to the mask with the preset pattern.

[0056] S306: On the second semiconductor layer of the second semi-ellipsoid, a first electrode electrically connected to the first semiconductor layer through the second semiconductor layer and the active layer is formed, a second electrode electrically connected to the second semiconductor layer, a first insulating layer located between the first electrode and the second semiconductor layer and the active layer, and a second insulating layer covering the exposed area of ​​the second semiconductor layer.

[0057] It should be understood that the formation of the first electrode hole is also included before the formation of the first electrode 14.

[0058] Specifically, photoresist can be applied based on step S204, and the photoresist can partially block the first semiconductor layer 11, which is equivalent to reserving the position of the first electrode hole. Then, an active layer 12 covering the first semiconductor layer is formed, and a second semiconductor layer 13 covering the second semi-ellipsoid of the active layer 12 is formed on the active layer 12. Then, the photoresist is removed, which is equivalent to forming the first electrode hole passing through the second semiconductor layer and the active layer.

[0059] In another embodiment, based on step S204, the active layer 12 and the second semiconductor layer 13 can be etched to form a first electrode hole through the second semiconductor layer 13 and the active layer 12.

[0060] After forming the first electrode hole, a first insulating layer 16 is deposited on the hole wall of the first electrode hole, and a second insulating layer 17 is deposited covering the exposed area of ​​the second semiconductor layer 13. A first electrode 14 electrically connected to the first semiconductor layer 11 is formed at the first electrode hole, a portion of the second insulating layer 17 is removed to form a second electrode hole, and a second electrode 15 electrically connected to the second semiconductor layer 13 is formed at the second electrode hole.

[0061] S307: Remove the etch barrier layer and form a third insulating layer on the second semiconductor layer above the first semiconductor layer of the first semi-ellipsoid.

[0062] The density of at least one of the first insulating layer 16 and the second insulating layer 17 is greater than the density of the third insulating layer 18, thereby increasing the probability of keeping the electrode side facing downwards. To further increase the probability of keeping the electrode side facing downwards, the density of both the first insulating layer 16 and the second insulating layer 17 can be set to be greater than the density of the third insulating layer 18.

[0063] In the aforementioned method for fabricating spherical LED chips, by forming an electrode on one side of the epitaxial layer of the sphere, the electrode side is more likely to remain facing downwards when the spherical LED chip is placed in a fluid. Furthermore, by setting the density of at least one of the first and second insulating layers to be greater than the density of the third insulating layer, the probability of the electrode side remaining facing downwards is further increased. This enables precise and mass transfer of the spherical LED chips to the grooves of the backplane, improving the efficiency and accuracy of LED chip transfer. Since the light-emitting surface of the spherical LED chip is necessarily spherical, the spherical LED shell as the light-emitting surface helps reduce total internal reflection within the spherical LED chip, thus improving light extraction efficiency.

[0064] This embodiment also provides an LED chip transfer method, such as... Figure 10 As shown, Figure 10 This is a basic flowchart of an LED chip transfer method provided in this embodiment. Figure 11 for Figure 10 The method corresponds to the schematic diagram, and the method includes: S401: Provides a suspension and a spherical LED chip as described above.

[0065] The density of the suspension can be set to be greater than that of the third insulating layer, and less than that of the first insulating layer 16 and the second insulating layer 17. Specifically, the suspension can be any one of alcohols, polyols, ketones, or halogenated hydrocarbons. The suspension can be used to transport the spherical LED chip 21 in a fluid form, and on the other hand, it can ensure that the spherical LED chip 21 is in a suspended state at the corresponding welding position, facilitating alignment. The provided spherical LED chip can be a spherical LED chip or an ellipsoidal LED chip.

[0066] S402: Provides a backplate with several grooves that fit the spherical LED chips.

[0067] It should be understood that the groove 23 that is adapted to the spherical LED chip 21 means that the outer contour of the spherical LED chip 21 and the shape of the groove 23 on the back plate 22 are exactly matched, so that the spherical LED chip 21 and the groove 23 on the back plate 22 can be precisely aligned.

[0068] In this example, when the spherical LED chip is an ellipsoidal LED chip, such as Figure 12 As shown, the shape of the groove 23 also matches the outer contour of the ellipsoidal LED chip, so that the ellipsoidal LED chip and the groove 23 on the back plate 22 can be precisely aligned.

[0069] It should be understood that if the height of the groove 23 is too low, the spherical LED chip 21 cannot be stably aligned with the groove 23, which may cause the spherical LED chip 21 to flow with the suspension. Therefore, the maximum height of the groove 23 perpendicular to the extension direction of the back plate 22 can be set between the height of the first electrode 14 perpendicular to the extension direction of the back plate 22 and half the height of the spherical LED chip 21 perpendicular to the extension direction of the back plate 22. The groove 23 includes a first pad 24 for alignment with the first electrode 14 and a second pad 25 for alignment with the second electrode 15.

[0070] In this example, the magnetism of the first electrode 14 and the first pad 24 can be set to be different, and the magnetism of the second electrode 15 and the second pad 25 can be set to be different. Since the magnetism of the first electrode 14 and the first pad 24 are different, and the magnetism of the second electrode 15 and the second pad 25 are different, the magnetic force can make the alignment of the first electrode 14 and the first pad 24, and the second electrode 15 and the second pad 25 more precise, thereby facilitating the alignment of the spherical LED chip 21 and the groove 23 on the backplate 22.

[0071] The pattern of the first pad 24 can be set to match the pattern of the first electrode 14, and the pattern of the second pad 25 can be set to match the pattern of the second electrode 15. For spherical LED chips 21 of different colors, a first electrode 14, first pad 24, second electrode 15, and second pad 25 can be designed to uniquely correspond to the color. Since the overlap between electrodes and pads with different patterns is small, the mutual adsorption force is also small. When a mismatch occurs, vibration can cause the mismatched spherical LED chip 21 to detach from the backplate 22 and re-adsorb, realizing the transfer of spherical LED chips 21 of different colors and achieving the effect of improving yield. For example, the first electrode 14 of the red spherical LED chip 21 can be set to be cylindrical and the second electrode 15 to be annular; the first electrode 14 of the blue spherical LED chip 21 can be set to be multi-dimensional cylindrical and the second electrode 15 to be multi-ringed; and the first electrode 14 of the green spherical LED chip 21 can be set to be triangular prism and the second electrode 15 to be triangular ringed. Then, the corresponding patterns of the first pad 24 and second pad 25 can be set on the backplate 22. Of course, the shapes of the first electrode 14 and the second electrode 15 of the spherical LED chip 21 of different colors can be freely set according to actual needs.

[0072] Since the pixels are composed of spherical LED chips 21 of three different colors (R, G, and B), during transfer, the spherical LED chips 21 of different colors can be made into different sizes, and the back plate 22 is provided with grooves 23 corresponding to the sizes of the spherical LED chips 21 of different colors. During assembly via suspension transfer, since the spherical LED chips 21 of different colors (R, G, and B) are of different sizes, the transfer begins with the largest spherical LED chip 21. For example, the largest red spherical LED chip 21 is transferred first, then the second largest green spherical LED chip 21, and then the smallest blue spherical LED chip 21. Of course, the sizes of the three types of spherical LED chips 21 (R, G, and B) can be freely set.

[0073] S403: Place the backplate horizontally in the suspension and disperse the spherical LED chips into the suspension.

[0074] S404: Control the suspension to carry the spherical LED chip in the horizontal direction so that the spherical LED chip is transferred to the groove.

[0075] After the spherical LED chip 21 is transferred onto the groove 23, the process also includes removing the suspension. Specifically, in one example, the suspension can be removed by heating to evaporate it, leaving only the spherical LED chip 21 on the groove 23. Then, the first electrode 14 is electrically connected to the first pad 24, and the second electrode 15 is electrically connected to the second pad 25, thereby ensuring the normal use of the spherical LED chip 21.

[0076] The aforementioned LED transfer method provides that the electrodes of the spherical LED chips are all disposed on one side of the epitaxial layer of the sphere, so that when the spherical LED chip is placed in a fluid, the electrode side is more likely to remain facing downwards. Furthermore, the density of at least one of the first and second insulating layers is greater than the density of the third insulating layer, further increasing the probability of the electrode side remaining facing downwards. Additionally, the density of the provided suspension is greater than the density of the third insulating layer, and the density of the suspension is less than the density of the first and second insulating layers, further increasing the probability of the electrode side remaining facing downwards. The maximum height of the backplate groove is between the height of the first electrode and half the height of the spherical LED chip, thus accurately and reliably attracting the spherical LED chips that fall into the groove. The magnetism of the first electrode is different from the magnetism of the first pad, and the magnetism of the second electrode is different from the magnetism of the second pad, avoiding misalignment between the spherical LED chip and the pad of the backplate. Therefore, the method achieves precise and large-scale transfer of spherical LED chips to the groove of the backplate, improving the efficiency and accuracy of LED chip transfer.

[0077] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A spherical LED chip, characterized in that, Includes an epitaxial layer of the sphere, electrodes, and an insulating layer; The spherical epitaxial layer includes a first semiconductor layer, an active layer enclosing the first semiconductor layer, and a second semiconductor layer enclosing the active layer. The electrode includes a first electrode and a second electrode disposed on one side of the epitaxial layer of the sphere and insulated from each other. The first electrode passes through the second semiconductor layer and the active layer and is electrically connected to the first semiconductor layer. The second electrode is electrically connected to the second semiconductor layer. The insulating layer includes a first insulating layer disposed between the first electrode, the second semiconductor layer, and the active layer; a second insulating layer disposed on one side of the spherical epitaxial layer to cover the exposed area of ​​the second semiconductor layer; and a third insulating layer disposed on the other side of the spherical epitaxial layer to cover the exposed area of ​​the second semiconductor layer. The density of at least one of the first insulating layer and the second insulating layer is greater than the density of the third insulating layer.

2. The spherical LED chip as described in claim 1, characterized in that, The second electrode surrounds the first electrode.

3. The spherical LED chip as described in claim 1 or 2, characterized in that, Both the first electrode and the second electrode comprise magnetic materials. The first electrode has a first magnetic property, and the second electrode has a second magnetic property. The first magnetic property and the second magnetic property are different.

4. The spherical LED chip as described in claim 1 or 2, characterized in that, The spherical epitaxial layer is either a spherical epitaxial layer or an ellipsoidal epitaxial layer.

5. A method for fabricating a spherical LED chip, characterized in that, The method includes: A first semiconductor layer, forming a first hemisphere, is formed on a first substrate; An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the first hemisphere, and a second semiconductor layer covering the first hemisphere is formed on the active layer. An etching barrier layer is deposited on the surface of the second semiconductor layer; Remove the first substrate and form a second hemisphere first semiconductor layer in the region above the first semiconductor layer of the first hemisphere; An active layer covering the first semiconductor layer is formed on the first semiconductor layer of the second hemisphere, and a second semiconductor layer covering the second hemisphere is formed on the active layer. On the second semiconductor layer of the second hemisphere, the following are formed respectively: a first electrode that passes through the second semiconductor layer and the active layer and is electrically connected to the first semiconductor layer, a second electrode that is electrically connected to the second semiconductor layer, a first insulating layer located between the first electrode and the second semiconductor layer and the active layer, and a second insulating layer that covers the exposed area of ​​the second semiconductor layer. Remove the etch barrier layer and form a third insulating layer on the second semiconductor layer of the first hemisphere.

6. The method for fabricating a spherical LED chip as described in claim 5, characterized in that, The first semiconductor layer formed on the first substrate as a first hemisphere includes: A first semiconductor layer is grown on the first substrate, a spherical particle is formed on the first semiconductor layer, and the spherical particle is used as a mask to etch the first semiconductor layer to obtain the first semiconductor layer of the first hemisphere.

7. A method for transferring LED chips, characterized in that, include: Provides a suspension and a spherical LED chip as described in any one of claims 1-4; A backplate is provided, the backplate having a plurality of grooves adapted to the spherical LED chip; The backplate is placed horizontally in the suspension, and the spherical LED chips are dispersed into the suspension. The suspension is controlled to carry the spherical LED chip in a horizontal direction, so that the spherical LED chip is transferred onto the groove.

8. The LED chip transfer method as described in claim 7, characterized in that, The groove includes a first pad for alignment with the first electrode and a second pad for alignment with the second electrode; The magnetism of the first electrode is different from that of the first pad, and the magnetism of the second electrode is different from that of the second pad.

9. The LED chip transfer method as described in claim 7 or 8, characterized in that, The density of the suspension is greater than the density of the third insulating layer, and the density of the suspension is less than the density of the first insulating layer and the density of the second insulating layer.

10. The LED chip transfer method as described in claim 7 or 8, characterized in that, The maximum height of the groove along the direction perpendicular to the back plate is between the height of the first electrode along the direction perpendicular to the back plate and half the height of the spherical LED chip along the direction perpendicular to the back plate.

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