Micro light-emitting diode package structure and forming method thereof

Abstract

To provide a micro LED package structure.SOLUTION: The present invention provides a micro LED package structure and a method for forming the same. The micro-LED package structure includes a first micro-LED die, a light-transmitting layer, a first insulating layer, and a redistribution layer. The first micro-LED die has an electrode, an electrode surface, a light emitting surface, and a plurality of side surfaces, the electrode surface and the light emitting surface are opposite to each other, the plurality of side surfaces are located between the electrode surface and the light emitting surface, the electrode has an upper portion and a lower portion, and a step portion is disposed between the upper portion and the lower portion. The light-transmissive layer is disposed on the light-emitting surface. The first insulating layer surrounds a plurality of side surfaces of the first micro-LED die. The redistribution layer is disposed on the electrode of the first micro-LED die and extends along the top, bottom, and step portions.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to a light-emitting diode, and more particularly to a micro light-emitting diode package structure and a method for forming the same. [Background technology]

[0002] With the advancement of electronic devices, each component within an electronic device is gradually being miniaturized. Taking the micro light-emitting diode (LED) packaging structure as an example, the reduction in the size of LED devices significantly increases the process difficulty, leading to problems such as a decrease in yield. Therefore, although existing micro LED packaging structures have gradually met their specific applications, they do not meet all requirements. Therefore, there are still some issues to be overcome regarding micro LED packaging structures. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention provides a micro LED packaging structure and a method for forming the same. [Means for solving the problem]

[0004] In one embodiment, a micro LED package structure is provided. The micro LED package structure includes a first micro LED die, a light-transmitting layer, a first insulating layer, and a redistribution layer. The first micro LED die has an electrode, an electrode surface, a light-emitting surface, and multiple side surfaces, with the electrode surface and the light-emitting surface facing each other and the multiple side surfaces located between the electrode surface and the light-emitting surface. The electrode has an upper and lower portion, and a step is provided between the upper and lower portions. The light-transmitting layer is disposed on the light-emitting surface. The first insulating layer is disposed to surround the multiple side surfaces of the first micro LED die. The redistribution layer is disposed on the electrode of the first micro LED die and extends along the upper, lower, and step portions.

[0005] In one embodiment, a method for forming a micro LED package structure is provided. A plurality of micro LED dies are arranged side by side on a first substrate, each having an electrode surface, a light-emitting surface, and multiple side surfaces. The electrode surface and the light-emitting surface face each other, and the multiple side surfaces are located between the electrode surface and the light-emitting surface. A transparent layer is provided to cover the light-emitting surface and multiple side surfaces of the plurality of micro LED dies. The first substrate is removed to expose the electrode surfaces of the plurality of micro LED dies. A first insulating layer is provided on the electrode surfaces of the plurality of micro LED dies, the first insulating layer being in direct contact with and covering the micro LED dies. A plurality of re-distribution layers are provided on the first insulating layer, and the plurality of re-distribution layers are electrically connected to the electrode surfaces of the plurality of micro LED dies through the first insulating layer. A plurality of conductive elements are provided on the plurality of re-distribution layers, and the plurality of conductive elements and the plurality of re-distribution layers are electrically connected. [Effects of the Invention]

[0006] The micro LED package structure of the present invention can be applied in various types of electronic devices. In order to make the features and advantages of this disclosure more clearly understandable, various embodiments are given below and described in detail in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0007] [Figure 1]1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 2] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 3A] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 3B] FIG. 2 is a close-up view of a micro LED die according to some embodiments of the present invention. [Figure 3C] 1A-1D illustrate a micro LED die stamp transfer process according to some embodiments of the present invention. [Figure 3D] 1A-1D illustrate a micro LED die stamp transfer process according to some embodiments of the present invention. [Figure 3E] FIG. 10 shows the top surfaces of a blue LED and a green LED with periodically arranged concave and convex patterns. [Figure 4] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 5] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 6] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 7] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 8A] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 8B] FIG. 10 is a diagram showing the connection between the electrodes and the tin paste through the bonding process. [Figure 8C] 10 shows the connection between the electrode and the redistribution layer by electroplating, sputtering or electron beam process. [Figure 9]1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 10] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 11] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 12] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 13] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 14] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 15] 1A-1C are cross-sectional views of a micro LED package structure at various stages in a formation method according to some embodiments of the present invention. [Figure 16] 1 is a top view of a micro LED package structure according to some embodiments of the present invention. [Figure 17] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to another embodiment of the present invention. [Figure 18] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to another embodiment of the present invention. [Figure 19] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to another embodiment of the present invention. [Figure 20] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to another embodiment of the present invention. [Figure 21] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to another embodiment of the present invention. [Figure 22] FIG. 2 is a top view of a micro LED package structure according to another embodiment of the present invention. [Figure 23A] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 23B] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 23C] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 24A] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 24B] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 24C] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 24D] FIG. 10 is a cross-sectional view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 25] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 26] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 27] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 28] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 29] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 30] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 31] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 32] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 33] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 34] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 35] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 36] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 37] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 38] 10A-10C are cross-sectional views of micro LED package structures at different stages in a forming method according to yet another embodiment of the present invention. [Figure 39] FIG. 10 is a top view of a micro LED package structure according to yet another embodiment of the present invention. [Figure 40] 1 illustrates a display module according to some embodiments of the present invention. [Figure 41] 1 illustrates a splicing display device according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following detailed description, taken in conjunction with the accompanying drawings, provides a better understanding of the embodiments of the present disclosure. It should be noted that, in accordance with standard industry practice, some features may not be drawn to scale. In fact, the sizes of different features may be increased or decreased for clarity of illustration. The following provides numerous embodiments or examples of the provided micro LED package structures and methods for forming the same, and specific examples of components and their arrangements are described to simplify the embodiments of the present disclosure. However, these descriptions are not intended to limit the present disclosure. For example, when a first component is disposed on a second component as described, not only are there embodiments in which the first and second components are in direct contact with each other, but there are also embodiments in which an additional component is disposed between the first and second components and the first and second components are not in direct contact with each other. Furthermore, component symbols or letters may be repeated in the embodiments or examples of the present disclosure, but this is for clarity of explanation and not to indicate a relationship between different embodiments or examples.

[0009] The directional terms used herein, such as "up," "down," "left," "right," and similar terms, refer to directions based on the figures, and therefore, the directional terms used are for purposes of illustrating the present disclosure and are not intended to be limiting.

[0010] In some embodiments of the present disclosure, terms such as "mounted," "connected," and the like, unless otherwise defined, can refer to two components in direct contact with each other, as well as to additional components between the two components. The terms "mounted" and "connected" can also include cases where both structures are movable or where both structures are fixed.

[0011] Furthermore, terms such as "first," "second," and similar terms in this description and claims are used to identify different components or distinguish between different embodiments or ranges, and are not used to limit the upper or lower limits of the number of components, or to limit the manufacturing or arrangement order of components.

[0012] In the following context, the terms "approximately," "substantially," or similar terms mean within 10%, 5%, 3%, 2%, 1%, or 0.5% of a given value or range of values. Quantities herein are approximate quantities, and this meaning may be implicit even if "approximately" or "substantially" is not specifically stated.

[0013] Unless otherwise defined, the terms (technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art. Furthermore, terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0014] The following is a description of variations of the embodiments. The same or similar part symbols are used to indicate the same or similar parts in different drawings and described embodiments. Also, additional steps may be provided before, during, or after the method, and some described steps may be replaced or eliminated in the methods of other embodiments.

[0015] In existing technologies, packaging materials typically cover micro LED dies to protect them from external impurities. Packaging materials can also electrically isolate multiple micro LED dies from each other to ensure electrical stability. However, as micro LED die sizes shrink, it becomes difficult for packaging materials to adequately cover the micro LED dies. In particular, when miniaturizing the die, removing the original substrate of the micro LED significantly reduces the die thickness, making many of the process methods for handling and fixing the die (such as adjusting the height of the probe tip, suction nozzle suction, and pressure fixing) in conventional packaging techniques impractical for micro LEDs. Furthermore, unexpected gaps are likely to occur between the micro LED die and the packaging material, which can cause unnecessary light scattering and parasitic capacitance, as well as reduce heat dissipation efficiency. Furthermore, unexpected stresses can be generated in the packaging material, potentially damaging the micro LED dies during manufacturing or use, resulting in unexpected losses. SUMMARY OF THE INVENTION Accordingly, the present invention provides a micro LED die and a method for forming the same to ameliorate at least the above-mentioned problems in the current art.

[0016] 1-3A, 4-8A, and 9-15 are cross-sectional views of micro LED package structures at various stages of a forming method according to some embodiments of the present invention. As shown in FIG. 1, a first substrate 10 is provided. In one embodiment, the first substrate 10 is or comprises: a Group IV element or Group IV compound, such as silicon (Si), diamond (C), silicon carbide (SiC), a Group III-V compound, such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), gallium phosphide (GaP), gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), other suitable materials, or combinations thereof, although the present disclosure is not limited thereto. In one embodiment, the first substrate 10 is or comprises a flexible substrate, a soft substrate, a rigid substrate, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, the first substrate 10 is or comprises glass, quartz, sapphire, ceramic, other suitable material, or combinations thereof, although the present disclosure is not limited in this respect. In one embodiment, the first substrate 10 is or includes polyimide (PI), polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), or other suitable materials, or combinations thereof, although the present disclosure is not limited thereto. For example, the first substrate 10 is a sapphire substrate. In one embodiment, the first substrate 10 is or comprises a transparent, translucent, or opaque substrate, although the present disclosure is not limited in this respect.

[0017] As shown in FIG. 2, in one embodiment, a first debond layer 11 is disposed on a first substrate 10 . In one embodiment, first release layer 11 is or comprises a thermal release, UV release, or other suitable material, or a combination thereof, although the present disclosure is not limited in this respect. It should be noted that although FIG. 2 shows an embodiment in which first release layer 11 completely covers the top surface of first substrate 10, the present disclosure is not limited thereto. In other embodiments, the first release layer 11 partially covers the top surface of the first substrate 10. For example, the first release layer 11 partially covers the top surface of the first substrate 10 corresponding to the location of the micro LED die to be subsequently installed.

[0018] As shown in FIG. 3A, in one embodiment, multiple micro LED dies 13 are disposed side by side on a first release layer 11 on a first substrate 10. These are the first micro light-emitting diode die, the second micro light-emitting diode die and the third micro light-emitting diode die. In one embodiment, the micro LED die 13 is or includes a flip chip micro LED die 13. For example, a plurality of micro LED dies 13 may be first placed on an adhesive layer (not shown) of a temporary substrate (not shown), and then the adhesive layer and the temporary substrate thereon may be removed by a laser transfer process or a similar process to transfer the plurality of micro LED dies 13 onto the first release layer 11, although the present disclosure is not limited thereto. Alternatively, the plurality of micro LED dies 13 may be transferred onto the first release layer 11 by a pick-up process.

[0019] 3B, which is an enlarged view of a micro LED die according to some embodiments of the present invention. As shown, in some embodiments, the flip-chip micro LED die 13 may have two reflective layers, for example, a first reflective layer 131 and a second reflective layer 132. The first reflective layer 131 is disposed on the micro LED die (e.g., semiconductor stack layer 133). The first reflective layer 131 reflects light emitted from the light emitting diode die (e.g., semiconductor stack layer 133), thereby increasing the external quantum efficiency (EQE) of the light emitting diode and the luminous efficiency of the light emitting diode. The second reflective layer 132 is disposed on the first reflective layer 131. The second reflective layer 132 can reflect laser light, where the wavelength of the laser light is less than 420 nm, and the first reflective layer 131 is closer to the active layer of the micro LED die 13 (e.g., located in the semiconductor stack layer 133) than the second reflective layer 132. Therefore, during the laser transfer process, the second reflective layer 132 is used to reflect the laser light to prevent the laser light from damaging the micro LED die 13. In one embodiment, the flip chip micro LED die 13 has only a first reflective layer 131 that reflects light emitted from the light emitting diode die (e.g., semiconductor stack layer 133), and does not have a second reflective layer 132 that reflects the wavelength of laser light.

[0020] 3C and 3D, which are diagrams illustrating a micro LED die stamp transfer process, respectively, according to some embodiments of the present invention. As shown in the figure, in one embodiment, the micro LED die 13 can be transferred onto the first release layer 11 by stamp transfer. The substrate used to transfer the micro LED die 13 includes a mounting substrate 160, an adhesive layer 170, and a sacrificial layer 140. The adhesive layer 170 is disposed on the mounting substrate 160, and the sacrificial layer 140 is disposed above the adhesive layer 170. In one embodiment, the sacrificial layer 140 is etched to form a support frame 142 that supports the micro LED die 13. When the micro LED die 13 is transferred onto the first release layer 11 by stamp transfer, the micro LED die 13 has a support fracture point obtained by fracture of the support frame 142. As shown in FIG. 3C, in one embodiment, the bearing fracture point is located on the light-emitting surface 13A of the micro LED die 13. As shown in FIG. 3D, in one embodiment, the bearing fracture point is located between both electrodes 130 of the micro LED die 13. However, the present disclosure is not limited to this. The support frame 142 can be connected to any position of the micro LED die 13, and thus can remain at the support fracture point at various positions after fracture. For example, in one embodiment, the bearing fracture point is located on the side of the micro LED die 13. In one embodiment, the support fracture points are located at diagonal positions on the sides of the micro LED die 13. In one embodiment, the micro LED die 13 has multiple support fracture points.

[0021] 3A , in one embodiment, each of the micro LED dies 13 has a light-emitting surface 13A, an electrode surface 13B, and a plurality of side surfaces 13C. The electrode surface 13B and the light-emitting surface 13A face each other, and the side surfaces 13C are located between the electrode surface 13B and the light-emitting surface 13A. Note that the electrode surface 13B refers to the surface of the micro LED die 13 itself on which the electrode 130 is installed, not the surface of the electrode 130. In one embodiment, the electrode surface 13B of the micro LED die 13 is arranged for electrical connection with other electronic elements via the electrodes 130, and the light emitting surface 13A is arranged for generating a light source. In these embodiments, the electrode surface 13B of the micro LED die 13 faces towards the first substrate 10, and the light emitting surface 13A faces away from the first substrate 10.

[0022] In one embodiment, the micro LED die 13 is a red LED, a blue LED, or a green LED. In one embodiment, the light emitting surfaces 13A of the red, blue, and green LEDs have a roughened structure. In one embodiment, the light-emitting surface 13A of the blue or green LED in the micro LED die 13 has a uniformly roughened structure. Referring also to FIG. 3E, FIG. 3E illustrates the periodically arranged textured upper surfaces (i.e., the light-emitting surfaces 13A) of the blue and green LEDs according to some embodiments of the present invention. For example, the blue and green LEDs themselves do not have an epitaxial substrate such as a patterned sapphire substrate (PSS) (e.g., the micro LED die 13 has a semiconductor stack layer 133 but no patterned sapphire substrate), and the light-emitting surfaces 13A have a periodically arranged textured pattern generated after peeling off the patterned sapphire substrate with a laser beam. Specifically, the textured pattern increases light extraction and adjusts the beam angle of the micro LED die 13. In one embodiment, the light-emitting surface 13A of the red LED in the micro LED die 13 has a non-uniform roughened structure (e.g., a non-uniform pattern). In one embodiment, chemical etching is performed on the light-emitting surface 13A to create a non-uniform roughened structure on the light-emitting surface 13A of the red LED in the micro-LED die 13.

[0023] It should be noted that although FIG. 3A and subsequent figures show multiple micro LED dies 13 with equal thickness, the present disclosure is not limited thereto. In one embodiment, the micro LED dies 13 may have different thicknesses. For example, any two of the red LED, blue LED, and green LED in the micro LED die 13 may have different thicknesses. For example, the blue LED and the green LED may have the same thickness, but the blue LED and the red LED may have different thicknesses, and the green LED and the red LED may have different thicknesses. Under such circumstances, the redistribution layer installed later can make the light-emitting surfaces 13A of the micro LED dies 13 with different thicknesses level with each other to maintain a desirable display effect.

[0024] 3A , in one embodiment, an adhesive layer 12 may be further disposed between the micro LED die 13 and the first release layer 11. For example, the adhesive layer 12 may be first disposed on the micro LED die 13, and then the micro LED die 13 together with the adhesive layer 12 may be transferred onto the first release layer 11. Alternatively, the adhesive layer 12 may be first disposed on the first release layer 11, and then the micro LED die 13 may be attached onto the adhesive layer 12. In one embodiment, adhesive layer 12 is or includes polyimide (PI), polybenzoxazole (PBO), epoxy, or other suitable material, or a combination thereof, although the present disclosure is not limited thereto.

[0025] 4 , in one embodiment, the adhesive layer 12 and the first release layer 11 that are not covered by the micro LED die 13 are first removed. For example, depending on the materials of the adhesive layer 12 and / or the first release layer 11, the adhesive layer 12 and the first release layer 11 may be removed using methods such as heating, laser, UV light, etc., but the present disclosure is not limited thereto. In other embodiments, the adhesive layer 12 and the first release layer 11 may be removed using a combination of physical methods or alone. Following the above process, a transparent layer 14 is provided to cover the light-emitting surface 13A and the side surface 13C of the micro LED die 13. For example, by compression molding, laminating, transfer molding, or other suitable methods, or a combination thereof, a light-transmitting layer 14 is blanket-formed on the micro LED die 13 to cover the light-emitting surface 13A and side surface 13C of the micro LED die 13, the side surface of the adhesive layer 12, the side surface of the first release layer 11, and the first substrate 10 exposed between the two micro LED dies 13.

[0026] In one embodiment, light-transmitting layer 14 is or includes epoxy, silicone, polyurethane, or other suitable material, or combinations thereof, although the present disclosure is not limited thereto. In one embodiment, the Shore D of the light-transmitting layer 14 is less than or equal to 90. For example, the Shore D of the light-transmitting layer 14 is 90, 80, 70, 60, 50, 40, 30, or any range of the above values. If the Shore D of the light-transmitting layer 14 is greater than 90, excessive stress may occur during the solidification process of the light-transmitting layer 14, causing the chip to tear.

[0027] In one embodiment, light emitted by the micro LED die 13 is transmitted through the light-emitting surface 13A and then outward through the transparent layer 14. Therefore, the light transmittance (e.g., light transmittance in the visible light range) of the transparent layer 14 is 80% or more to provide a desirable display effect, but the present disclosure is not limited thereto. For example, the light transmittance of the transparent layer 14 may be 80%, 85%, 90%, 95%, 100%, or any range of the aforementioned values.

[0028] 5 , in one embodiment, first, the second substrate 16 is attached onto the light-transmitting layer 14, and the first substrate 10 is inverted. For example, first, the second release layer 15 is provided on the second substrate 16, and then the second substrate 16 is attached onto the light-transmitting layer 14 via the second release layer 15. Alternatively, the second release layer 15 may be provided on the light-transmitting layer 14, and then the second substrate 16 may be attached onto the second release layer 15.

[0029] In one embodiment, the second substrate 16 is or includes a Group IV element or compound, such as silicon, diamond, silicon carbide, a Group III-V compound, such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), gallium phosphide (GaP), gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or other suitable material, or a combination thereof, although the present disclosure is not limited thereto. In one embodiment, second substrate 16 is or comprises a flexible substrate, a soft substrate, a rigid substrate, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, second substrate 16 is or comprises glass, quartz, sapphire, ceramic, or other suitable material, or combinations thereof, although the present disclosure is not limited in this respect. In one embodiment, the second substrate 16 is or includes, but is not limited to, polyimide (PI), polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), or other suitable materials or combinations thereof. For example, the second substrate 16 is a sapphire substrate. In one embodiment, second substrate 16 is or comprises an optically transparent substrate, a semi-transparent substrate, or an opaque substrate, although the present disclosure is not limited in this respect. In one embodiment, the material of second substrate 16 is similar to or the same as the material of first substrate 10, although the present disclosure is not limited in this respect.

[0030] In one embodiment, second release layer 15 is or comprises a thermal release, UV release, or other suitable material, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, the material of second release layer 15 is similar to or the same as the material of first release layer 11, although the present disclosure is not limited in this respect.

[0031] Following the above steps, the first substrate 10 is removed. In one embodiment, the first substrate 10 is removed by a laser lift-off process, other suitable processes, or a combination thereof, but the present disclosure is not limited thereto. For example, the first substrate 10 is removed by removing the gel (if present, the gel is not shown) between the first substrate 10 and the micro LED die 13. It should be noted that the above methods are merely examples, and the present disclosure is not limited thereto. In some other embodiments, a portion of the first substrate 10 can be directly removed and separated from the micro LED die 13 by physical destruction.

[0032] As shown in FIG. 6, in one embodiment, after removing the first substrate 10, the first release layer 11, the adhesive layer 12, and a portion of the light-transmitting layer 14 are removed to expose the electrode surface 13B and a portion of the side surface 13C of the micro LED die 13. In one embodiment, the materials are removed by an etching process, a polishing process, or other suitable process, or a combination thereof, although the present disclosure is not limited in this respect.

[0033] In one embodiment, after removing a portion of the light-transmitting layer 14, the ratio between the thickness t1 of the remaining light-transmitting layer 14 and the thickness t2 of the micro LED die 13 is between 1:1 and 30:1, although the present disclosure is not limited thereto. For example, the ratio between the thickness t1 of the light-transmitting layer 14 and the thickness t2 of the micro LED die 13 may be 1:1, 3:1, 5:1, 7:1, 10:1, 15:1, 20:1, 25:1, any number between the aforementioned numbers, or any range of numbers. In one embodiment, the ratio between the thickness t1 of the light-transmitting layer 14 and the width w1 of the micro LED die 13 is between 30:1 and 0.4:1, but the present disclosure is not limited thereto. For example, the ratio between the thickness t1 of the light-transmitting layer 14 and the width w1 of the micro LED die 13 may be 30:1, 20:1, 15:1, 10:1, 5:1, 2:1, 1:1, 0.4:1, any value between the above values, or any range of values. Achieving a specific relationship between the thickness of the light-transmitting layer 14 and the thickness / width of the micro LED die 13 can effectively improve the display effect of the entire device.

[0034] As shown in FIG. 7 , in one embodiment, the first insulating layer 17 is disposed on the electrode surface 13B of the micro LED die 13, such that the first insulating layer 17 directly contacts the electrode surface 13B of the micro LED die 13 and exposes the electrode 130 of the micro LED die 13. In one embodiment, the micro LED die 13 has two electrodes 130, and the two electrodes 130 are spaced apart from each other. Under such circumstances, the first insulating layer 17 fills the gap between the two electrodes 130, such that the electrode surface 13B of the micro LED die 13 is completely covered by the first insulating layer 17, except for the electrodes 130. In one embodiment, the first insulating layer 17 is continuous and surrounds the sides of the micro LED die 13. In one embodiment, the first insulating layer 17 is continuous and surrounds the sides of the electrodes 130 of the micro LED die 13.

[0035] In one embodiment, a first contact surface S1 is formed between the first insulating layer 17 and the transparent layer 14, and a second contact surface S2 is formed between the first insulating layer 17 and the electrode surface 13B of the micro LED die 13, and the first contact surface S1 and the second contact surface S2 are not coplanar. Specifically, the horizontal height of the remaining transparent layer 14 is made lower than that of the electrode surface 13B by the aforementioned removal process, so that the horizontal height of the first contact surface S1 in FIG. 7 is lower than that of the second contact surface S2, and the first insulating layer 17 also partially covers the side surface 13C of the micro LED die 13. By having the first insulating layer 17 partially cover the side surface 13C of the micro LED die 13, the contact area between the first insulating layer 17 and the micro LED die 13 is increased, thereby improving the density between the two elements. In one embodiment, the first insulating layer 17 is continuous and surrounds a portion of the side surface 13C of the micro LED die 13.

[0036] In one embodiment, first insulating layer 17 is or includes epoxy resin, polyimide (PI), polybenzoxazole (PBO), silicon, silicon dioxide, silicon nitride, or combinations thereof, although the present disclosure is not limited thereto. In one embodiment, the material of the first insulating layer 17 is different from the material of the light-transmitting layer 14. In other embodiments, the material of the first insulating layer 17 may be similar to the material of the light-transmitting layer 14, but at least some physical properties of the two are different. For example, the hardness of the first insulating layer 17 may be different from the hardness of the light-transmitting layer 14. Alternatively, the light transmittance of the first insulating layer 17 may be different from the light transmittance of the light-transmitting layer 14.

[0037] In one embodiment, the Shore D of the first insulating layer 17 is greater than or equal to 40. For example, the Shore D of the first insulating layer 17 is 40, 50, 60, 70, 80, 90, 100, or any range of the aforementioned values. If the Shore D of the first insulating layer 17 is less than the aforementioned values, the first insulating layer 17 may stretch inward due to stress during subsequent processing, potentially causing the chip to tear.

[0038] In one embodiment, the optical transmittance (e.g., optical transmittance in the visible light range) of the first insulating layer 17 is 70% or less, for example, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, or any range of values ​​therein. In one embodiment, the light transmittance of the first insulating layer 17 may be lower than the light transmittance of the light transmitting layer 14 . In one embodiment, the first insulating layer 17 is made of or has a material with an optical absorptivity of greater than 90%, thereby adjusting the optical transmittance of the first insulating layer 17. For example, black dispersed particles such as carbon black are added to the first insulating layer 17 to reduce the optical transmittance of the first insulating layer 17 to less than 10%, thereby making the first insulating layer 17 black. By making the first insulating layer 17 black, the proportion of black in each micro LED package structure in the top view can be increased, thereby improving the display effect of the entire device, such as improving the contrast of a display device having the micro LED package structure. In one embodiment, the proportion of black in the micro LED package structure reaches 80% or more.

[0039] As shown in FIG. 8A, in one embodiment, a plurality of re-distribution layers 18 are disposed on the first insulating layer 17, and the re-distribution layers 18 pass through the first insulating layer 17 and are electrically connected to the electrodes 130 on the electrode surface 13B of the micro LED die 13, respectively.

[0040] In one embodiment, the redistribution layer 18 is formed on the electrode 130 by a plating process such as electroplating, sputtering, or electron beam evaporation. Under these circumstances, the contact surface between the redistribution layer 18 and the electrode 130 may have a clear boundary or may be a flat surface. FIG. 8B illustrates the electrode 130 and the tin paste SP connected by a bonding process. Specifically, in FIG. 8B, the electrode 130 and the tin paste SP have a blurred interface compared to the rough interface created by the bonding process. FIG. 8C illustrates the electrode and the redistribution layer connected by an electroplating, sputtering, or electron beam process. The contact surface between the redistribution layer 18 and the electrode 130 formed by the electroplating, sputtering, or electron beam process has a smooth interface (the clear interface shown in FIG. 8C). That is, the roughness of the contact surface between the redistribution layer 18 and the electrode 130 is less than the roughness of the contact surface created by the bonding process. For example, the maximum roughness of the contact surface between the re-distribution layer 18 and the electrode 130 does not exceed 1 μm, but the present disclosure is not limited thereto. Since the contact surface between the re-distribution layer 18 and the electrode 130 has a clear boundary and a flat surface, the reliability of the micro LED package structure 1 is improved.

[0041] In one embodiment, the re-distribution layer 18 is conformally formed on the surface of the electrode 130, such that the re-distribution layer 18 conforms to the surface shape of the electrode 130. For example, as shown in FIG. 8C , the electrode 130 of the micro LED die 13 has an upper portion 130A and a lower portion 130B, and the upper portion 130A and the lower portion 130B have a step. Under such circumstances, the re-distribution layer 18 is disposed on the electrode 130 along the upper portion 130A, the lower portion 130B, and the step between them, and has a shape similar to the electrode 130.

[0042] As shown in FIG. 9, in one embodiment, the redistribution layer 18 has vertical connections 18A and horizontal connections 18B, where the vertical connections 18A are electrically connected to the micro LED die 13 and the horizontal connections 18B are electrically connected to other electronic elements, such as the conductive elements 20 presented below. In one embodiment, when the total thicknesses of the semiconductor stack layers of the micro LED die 13 are different from each other, the extending lengths (or thicknesses) of the vertical connecting portions 18A of the redistribution layer 18 are different. Thus, the light emitting surfaces 13A of the micro LED dies 13 are substantially coplanar, and the horizontal connections 18B of the re-distribution layers 18 corresponding to the micro LED dies 13 are also substantially coplanar.

[0043] In one embodiment, the redistribution layer 18 is or comprises a conductive material, such as, but not limited to, a metal, a metal compound, or other suitable conductive material, or a combination thereof. For example, the metal may be tin (Sn), copper (Cu), gold (Au), silver (Ag), nickel (Ni), indium (In), platinum (Pt), palladium (Pd), iridium (Ir), titanium (Ti), chromium (Cr), tungsten (W), aluminum (Al), molybdenum (Mo), magnesium (Mg), zinc (Zn), germanium (Ge), or an alloy thereof. For example, the metal compound may be tantalum nitride (TaN), titanium nitride (TiN), tungsten silicide (WSi2), indium tin oxide (ITO), etc.

[0044] 9, in one embodiment, a second insulating layer 19 is disposed on the first insulating layer 17, and the second insulating layer 19 covers the re-distribution layer 18. That is, the re-distribution layer 18 is embedded in the second insulating layer 19. In one embodiment, the second insulating layer 19 is or comprises an epoxy resin, a polyimide, a polybenzoxazole, a silicone resin, a silicon oxide, a silicon nitride, or a combination thereof, although the present disclosure is not limited thereto. In one embodiment, the material of second insulating layer 19 is similar to or the same as the material of first insulating layer 17, although the present disclosure is not limited in this respect.

[0045] In one embodiment, the optical transmittance (e.g., optical transmittance in the visible light range) of second insulating layer 19 is 70% or less, for example, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, or any range of values ​​therein. In one embodiment, the light transmittance of second insulating layer 19 may be less than the light transmittance of light transmitting layer 14 . In one embodiment, the second insulating layer 19 is made of or contains a material with an optical absorption coefficient of greater than 90%, thereby adjusting the optical transmittance of the second insulating layer 19. For example, black dispersed particles such as carbon black may be added to the second insulating layer 19 to reduce the optical transmittance of the second insulating layer 19 to less than 10%, thereby making the second insulating layer 19 black. Making the second insulating layer 19 black increases the proportion of black in each micro LED package structure in the top view, thereby improving the display effect of the entire device.

[0046] In one embodiment, the optical transmittance of the second insulating layer 19 is greater than that of the first insulating layer 17. For example, the first insulating layer 17 can be opaque black, and the second insulating layer 19 can be transparent or translucent of any color. Under these circumstances, a high proportion of black can be maintained in each micro LED package structure in the top view. In one embodiment, the high percentage of black is 80% or more, although the present disclosure is not limited in this respect. In one embodiment, the first insulating layer 17 can be opaque black and the second insulating layer 19 can be semi-transparent or opaque black, further increasing the proportion of black in each micro LED package structure in a top view.

[0047] As shown in FIG. 10, a plurality of conductive elements 20 are disposed on the second insulating layer 19 and the redistribution layer 18 to electrically connect the conductive elements 20 and the redistribution layer 18 . In one embodiment, conductive element 20 is a bonding pad, although the present disclosure is not limited thereto. In one embodiment, the conductive element 20 is or comprises a conductive material. For example, the conductive material may be, but is not limited to, a metal, a metal compound, or any other suitable conductive material, or a combination thereof. For example, the metal may be tin, copper, gold, silver, nickel, indium, platinum, palladium, iridium, titanium, chromium, tungsten, aluminum, molybdenum, magnesium, zinc, germanium, or an alloy thereof. For example, the metal compound may be tantalum nitride, titanium nitride, tungsten silicide, indium tin oxide, or the like. In one embodiment, the material of the conductive element 20 is similar to or the same as the material of the redistribution layer 18, although the present disclosure is not limited in this respect.

[0048] As shown in FIG. 11, in one embodiment, a hard mask layer 21 is disposed on the second insulating layer 19, with the hard mask layer 21 surrounding the conductive elements 20. In one embodiment, the patterned hard mask layer 21 is formed by a lithography process, other suitable processes, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, hard mask layer 21 comprises silicon oxide, although the present disclosure is not limited in this respect. In one embodiment, the hard mask layer 21 exposes a portion of the second insulating layer 19, making the exposed second insulating layer 19 a cut area for use in subsequent processes. In one embodiment, three micro LED dies 13 are defined as a set, and the second insulating layer 19 between the sets of micro LED dies 13 is exposed (i.e., not covered by the hard mask layer 21). It should be noted that the above quantities are merely examples, and the present disclosure is not limited thereto.

[0049] 12, using the hard mask layer 21 as a protective layer, the second insulating layer 19 between one set of micro LED dies 13 (e.g., three shown in FIG. 12) and another set of micro LED dies 13 (not shown), as well as the underlying first insulating layer 17, transparent layer 14, and second release layer 15, are cut down to the second substrate 16. For example, plasma dicing can be used to perform the above process, but the present disclosure is not limited thereto. In other embodiments, the cutting process between the two sets of micro LED dies 13 can be performed using a laser, a knife, or other suitable method or tool, or a combination thereof. In one embodiment, there are multiple sets of micro LED dies 13 on one second substrate 16, and the light-transmitting layer 14, the first insulating layer 17, and the second insulating layer 19 of one set of micro LED dies 13 are covered, and after this cutting process, they are separated (not continuous) from the corresponding elements covering the other set of micro LED dies 13.

[0050] 13 and 14 , in one embodiment, first, the third substrate 23 is attached onto the conductive element 20, and the second substrate 16 is inverted. For example, first, the third release layer 22 is provided on the third substrate 23, and then the third substrate 23 is attached onto the conductive element 20 via the third release layer 22. Alternatively, first, the third release layer 22 can be provided on the conductive element 20, and then the third substrate 23 can be attached onto the third release layer 22.

[0051] In one embodiment, the third substrate 23 is or comprises a Group IV element or compound, such as silicon, diamond, silicon carbide, a Group III-V compound, such as gallium nitride (GaN), aluminum gallium nitride (AlGan), aluminum nitride (AlN), gallium phosphide (GaP), gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), or other suitable material, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, the third substrate 23 is or comprises a flexible substrate, a soft substrate, a rigid substrate, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, third substrate 23 is or comprises glass, quartz, sapphire, ceramic, or other suitable material, or combinations thereof, although the present disclosure is not limited in this respect. In one embodiment, the third substrate 23 is or includes polyimide (PI), polycarbonate (PC), polyethylene terephthalate (PET), polypropylene (PP), or other suitable material, or a combination thereof, although the present disclosure is not limited thereto. For example, the third substrate 23 is a sapphire substrate. In one embodiment, the third substrate 23 is or comprises a light-transmitting substrate, a semi-light-transmitting substrate, or an opaque substrate, although the present disclosure is not limited thereto. In one embodiment, the material of the third substrate 23 is similar to or the same as the material of the first substrate 10, although the present disclosure is not limited in this respect. In one embodiment, the third release layer 22 is or comprises a thermal release, UV release, or other suitable material, or a combination thereof, although the present disclosure is not limited in this respect. In one embodiment, the material of third release layer 22 is similar to or the same as the material of first release layer 11, although the present disclosure is not limited in this respect.

[0052] Following the above process, the second substrate 16 is removed. For example, depending on the type of second release layer 15, the second release layer 15 may be made to lose its adhesiveness by heating, UV light, laser, or other methods, and then the second substrate 16 on top of it may be removed. Then, the second release layer 15 may be removed by a physical or chemical method. It should be noted that the second release layer 15 and the second substrate 16 may also be removed simultaneously in the same process using an appropriate method, and are not limited to the above method.

[0053] 15, in one embodiment, the third substrate 23 is removed. For example, depending on the type of third release layer 22, heating, UV light, laser, or other methods may be used to cause the third release layer 22 to lose its adhesiveness, and the third substrate 23 thereon may be removed. Subsequently, the third release layer 22 is removed by a physical or chemical method. Note that the third release layer 22 and the third substrate 23 may also be removed simultaneously in the same process using an appropriate method, and the method is not limited to the above.

[0054] Also referring to Figure 16, Figure 16 is a top view of a micro LED package structure according to some embodiments of the present invention, and Figure 15 is a cross-sectional view taken along A-A' in Figure 16. As shown in Figure 16, after the above-mentioned processes, a micro LED package structure 1 is formed. In one embodiment, the conductive element 20 is a negative conductive element 20b or a positive conductive element 20a. The micro LED package structure 1 has three micro LED dies 13 arranged side by side, and one electrode 130 of each micro LED die 13 is commonly electrically connected to one common negative conductive element 20b, and the other electrode 130 of each micro LED die 13 is respectively connected to the positive conductive element 20a. In one embodiment, the shape of the conductive elements 20 may be the same in top view. In one embodiment, the shape of the conductive element 20 in top view may vary. In one embodiment, the common conductive element 20 is square in shape and has one triangular notch, and the other non-common conductive elements 20 are square in shape. In one embodiment, the triangular notch of the common conductive element 20 is located at the upper left, upper right, lower left, or lower right corner of the square. In one embodiment, the common conductive element 20 is square in shape with two triangular notches. It should be noted that the configuration shown in FIG. 16 is merely an example, and the present disclosure is not limited thereto. In other embodiments, the micro LED package structure 1 has more or less than three micro LED dies 13, and the multiple micro LED dies 13 are individually connected to different conductive elements 20. In one embodiment, the electrode connection manner of the micro LED die 13 in the micro LED package structure 1 may be different from that described above. For example, one electrode 130 of each micro LED die 13 is commonly connected to a common positive conductive element, and the other electrode 130 of each micro LED die 13 is individually connected to a negative conductive element (not shown).

[0055] The above-mentioned process can realize a micro LED package structure 1 with simple processes. Meanwhile, by having the first insulating layer 17 cover the micro LED die 13 over a large area and partially in a horizontal orientation, it is possible to ensure stress control around the micro LED die 13 and provide better insulation between the micro LED die 13 and other elements, thereby realizing a micro LED package structure 1 with a high yield. In addition, compared with an electrical characteristic test for a single micro LED die 13, by performing the electrical characteristic test on the micro LED package structure 1 as a unit, the test contacts are transferred from six small-area electrodes 130 to four large-area conductive elements 20, which greatly reduces the difficulty of the test and reduces the cost of the test.

[0056] 17 to 21 are cross-sectional views of micro LED package structures at various stages in a method for forming the same in accordance with another embodiment of the present invention. Note that FIG. 17 is a process subsequent to FIG. 9, and all previous processes are shown in FIGS. 1 to 9, and will not be described in detail here. In addition, processes similar to those described above will not be described in detail here. The main difference between this embodiment and the previous embodiment is that the conductive elements 24 in this embodiment are metal pillars, rather than bonding pads as in the previous embodiment. It should be noted that using metal pillar conductive elements 24 can increase the thickness and volume of the metal layer, which brings significant benefits in current distribution, cooling of the LED, stress relief, pressure relief during subsequent die bonding, and improving component lifespan. In one embodiment, the metal pillar conductive element 24 is formed by electroplating, evaporation, screen printing, vacuum spraying, or other methods, and its thickness is several to several tens of times that of the bonding pad conductive element 20 in the other embodiment described above. In one embodiment, the thickness of the metal pillar conductive element 24 is 5 μm to 100 μm.

[0057] Continuing to refer to FIG. 9, in one embodiment, as shown in FIG. 17, a plurality of conductive elements 24 are disposed on the second insulating layer 19 and the redistribution layer 18, and the conductive elements 24 and the redistribution layer 18 are electrically connected. In one embodiment, the conductive elements 24 are metal posts, although the present disclosure is not limited in this respect. In one embodiment, the material of the conductive element 24 is similar to or the same as the material of the redistribution layer 18, although the present disclosure is not limited in this respect.

[0058] In one embodiment, a filler material layer 25 is further disposed on the second insulating layer 19 , the filler material layer 25 surrounding the conductive elements 24 . In one embodiment, filler material layer 25 is or includes polyimide (PI), epoxy, other suitable materials, or combinations thereof, although the present disclosure is not limited in this respect.

[0059] In one embodiment, the light transmittance of filler material layer 25 (e.g., light transmittance in the visible light range) is 70% or less, such as 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, or any range of values ​​therein. In one embodiment, the filler material layer 25 is made of or has a material with a light absorption rate of greater than 90%, thereby adjusting the light transmittance of the filler material layer 25. For example, adding black dispersed particles such as carbon black to the filler material layer 25 reduces the light transmittance of the filler material layer 25 to less than 10%, thereby making the filler material layer 25 appear black. Making the filler material layer 25 appear black optically shields elements (e.g., the redistribution layer 18) located below the filler material layer 25, which can facilitate the optical equipment of an imaging device, for example, to better align the conductive elements 24 with other electronic elements during a subsequent bonding process.

[0060] In one embodiment, filler material layer 25 is or includes a material with high light absorption. In one embodiment, the light absorptivity of the filler material layer 25 is greater than the light absorptivity of the second insulating layer 19 .

[0061] As shown in FIG. 18 , in one embodiment, similar to the above, cutting is performed on the filler material layer 25 between one set of micro LED dies 13 (e.g., three as shown in FIG. 18 ) and another set of micro LED dies 13 (not shown), as well as the second insulating layer 19, first insulating layer 17, light-transmitting layer 14, and second release layer 15 underneath. For example, plasma dicing can be used to perform the above steps, although the present disclosure is not limited thereto. In other embodiments, the cutting process between the two sets of micro LED dies 13 can be performed using, for example, a laser, a knife, or other suitable method or tool, or a combination thereof.

[0062] As shown in FIGS. 19 and 20, in one embodiment, first, the third substrate 23 is attached onto the conductive element 24, and the second substrate 16 is turned over. For example, first, the third release layer 22 is placed on the third substrate 23, and then the third substrate 23 is bonded to the conductive element 24 via the third release layer 22. Alternatively, the third release layer 22 can be placed on the conductive element 24 first, and then the third substrate 23 can be bonded to the third release layer 22. Following the above steps, the second substrate 16 is removed.

[0063] As shown in FIG. 21, in one embodiment, the third substrate 23 is removed. For example, depending on the type of the third release layer 22, the third release layer 22 may be made to lose its adhesiveness by heating, UV light, laser, etc., and the third substrate 23 thereon may be removed. Subsequently, the third release layer 22 is removed by a physical or chemical method. It should be noted that the third release layer 22 and the third substrate 23 can be removed simultaneously in the same process by using an appropriate method, and are not limited to the above-mentioned method.

[0064] In addition to the advantages of this embodiment over the previous embodiment, the conductive element 24 in this embodiment has a larger volume, which allows for better electrical connection between the conductive element 24 and other elements. Also referring to Figure 22, Figure 22 is a top view of a micro LED package structure according to some embodiments of the present invention, and Figure 22 is a cross-sectional view taken along line B-B' in Figure 21. In one embodiment, the shape of the conductive element 24 in the top view is the same. In one embodiment, the shape of the conductive elements 24 varies in top view. In one embodiment, the common conductive element 24 is square in shape with one triangular notch, and the other non-common conductive elements 24 are square in shape. In one embodiment, the triangular notch of the common conductive element 24 is located at the upper left, upper right, lower left, or lower right corner of the square. In one embodiment, the common conductive element 24 is square in shape with two triangular notches. It should be noted that the present disclosure is not limited to the specific shape, size, material, etc. of the conductive element, and a person skilled in the art can select an appropriate conductive element to replace the above-described conductive element 20, conductive element 24, and / or conductive element 37 as needed.

[0065] The above has already generally described a micro LED package structure with a specific redistribution structure and a method for forming the same according to some embodiments of the present invention. The above micro LED package structure is manufactured using the redistribution last (RDL last) method. The following text will present some variations of the micro LED package structure according to another embodiment of the present invention, and will depict a micro LED package structure manufactured by another redistribution last method. Specifically, the main difference between the following various embodiments and the above-described embodiments is that the micro LED package structures in the following embodiments may further include additional elements or features, or may form the various elements or features in a different formation sequence.

[0066] 23A-23C are cross-sectional views of micro LED package structures according to further embodiments of the present invention. In one embodiment, the micro LED packaging structure further includes reflective structures (for example, reflective structures 26a to 26c below), and the reflective structures are disposed around the micro LED die 13.

[0067] As shown in Figure 23A, the reflective structure 26a is disposed around the micro LED die 13. In one embodiment, the bottom surface of the reflective structure 26a may be flush with the electrode surface 13B of the micro LED die 13, although the present disclosure is not limited thereto. Alternatively, as shown in Figure 23B, the reflective structure 26b is conformally disposed on the bottom surface (e.g., electrode surface 13B) of the micro LED die 13 and between two micro LED dies 13, exposing the electrodes 130 of the micro LED dies 13. Under such circumstances, the reflective structure 26b has a larger coverage area than the reflective structure 26a, achieving a more favorable light reflection effect.

[0068] In one embodiment, the reflective structure 26 a or reflective structure 26 b includes a reflective material such as, but not limited to, silver (Ag), aluminum (Al), copper (Cu), chromium (Cr), titanium (Ti), or the like, or a combination thereof. Alternatively, the reflective material may be or include, but not limited to, white paint or other white materials, or the like, or a combination thereof. In one embodiment, before forming the first insulating layer 17 (e.g., during the formation process of FIG. 6 ), the reflective structure 26 a or the reflective structure 26 b can be formed on the micro LED die 13 by electroplating, chemical vapor deposition, sputtering, resistive heating evaporation, electron beam evaporation, or other suitable formation process, or a combination thereof. In one embodiment, the reflecting structure 26a or the reflecting structure 26b includes multiple film layers with different refractive indices to form a distributed Bragg reflector.

[0069] Alternatively, as shown in Figure 23C, a reflective structure 26c may be provided to replace the first insulating layer 17. Under such circumstances, the micro LED package structure does not have a first insulating layer, and the reflective structure 26c is used for electrical isolation and light reflection at the same time. In one embodiment, a reflective material can be directly applied to replace the first insulating layer 17. For example, during the fabrication process of Figure 7, no dielectric material is applied, thus eliminating the formation of the first insulating layer 17, and instead applying a reflective material to form the reflective structure 26c. Under these circumstances, the reflective structure 26c can have multiple film layers with different refractive indices to form a distributed Bragg reflector.

[0070] 24A and 24B are cross-sectional views of a micro LED package structure according to yet another embodiment of the present invention. In one embodiment, the light-transmitting layer 14 of the micro LED package structure has a roughened structure to improve the display effect. For example, an uneven surface or a surface with a specific curvature can converge or scatter the light beams from the micro LED die 13. As shown in FIG. 24A , the light-transmitting layer 14 has an irregularly roughened surface 14s2. Under these circumstances, the light beams emitted from the micro LED die 13 are dispersed by the influence of the roughened surface 14s2, resulting in a uniform light beam divergence.

[0071] 24B, the light-transmitting layer 14 may have a regularly roughened surface 14s3. For example, the light-transmitting layer 14 may have a plurality of lens units that protrude from the roughened surface 14s3 of the light-transmitting layer 14 in an array. However, the present disclosure is not limited to this. In other embodiments, the number of lens units in the light-transmitting layer 14 corresponds to the number of micro LED dies 13. For example, when the number of micro LED dies 13 is three, the number of lens units is also three, and in this case, each lens unit corresponds to one micro LED die 13 and is installed on the micro LED die 13 to achieve the light control effect.

[0072] In one embodiment, an optical layer (not shown) may be disposed on the light-transmitting layer 14 to improve the optical transmittance of light emitted by the micro LED die 13 through the light-transmitting layer 14. Figures 24C and 24D are cross-sectional views of a micro LED package structure according to yet another embodiment of the present invention. Figure 24D is an enlarged view of region A in Figure 24C. As shown, the conductive element 24 has a recessed structure CS at a position adjacent to the second insulating layer 19, and a filler material layer 25 surrounds the conductive element 24 and is filled into the recessed structure CS of the conductive element 24. In one embodiment, the inner recessed structures CS are located at both ends of the conductive element 24, and the filler material layer 25 is filled into the inner recessed structures CS located at both ends of the conductive element 24. In one embodiment, the inner recessed structure CS is disposed in a ring shape around the periphery of the conductive element 24, and the filling material layer 25 is filled into the inner recessed structure CS located around the periphery of the conductive element 24. In one embodiment, the internal concave structure CS gradually tapers from the edge of the conductive element 24 toward the interior of the conductive element 24 . In one embodiment, the inner concave structure CS is cone-shaped in cross section. In some embodiments, the filler material layer 25 has fillers 250 (e.g., the black parts in FIG. 24D ) and diffusing particles 251 (Filler) (e.g., the white parts in FIG. 24D ). In some embodiments, the diffusing particles comprise titanium dioxide (TiO2), silicon dioxide (SiO2), boron oxide (BN), aluminum oxide (Al2O3), or zirconia (ZrO2). In some embodiments, the diffusing particles include hollow silicon dioxide (SiO2) or solid silicon dioxide (SiO2). In some embodiments, filler material layer 25 has diffusing particles of two or more different sizes, such as two different sizes, three different sizes, four different sizes, or five or more different sizes. In some embodiments, the diffusing particles are spherical or rectangular. In some embodiments, filler material layer 25 has spherical diffusing particles of two or more different radii. In some embodiments, the filler material layer 25 fills the area of ​​the inner recessed structure CS and may comprise only filler 250 . In some embodiments, the filler material layer 25 fills the area of ​​the inner concave structure CS and can include fillers 250 and diffusing particles 251 (Filler).

[0073] In one embodiment, the concave structure CS is a structural feature created by forming an interface between the seed layer of the conductive element 24 and the conductive element 24 itself, although the present disclosure is not limited thereto. This structural feature can increase the adhesion between the conductive element 24 and the filler material layer 25 (e.g., increase the contact area). The filler material layer 25 is filled into the concave structure CS located on the conductive element 24, which can improve the reliability of the micro LED package structure. Figures 25 to 38 are cross-sectional views of micro LED package structures at various stages of a forming method according to further embodiments of the present invention, respectively. It should be noted that the materials and functions of the elements and components shown in Figures 25 to 38 are similar or identical to those of the elements and components shown in Figures 1 to 22, respectively, and therefore will not be described in detail here. For example, the first substrate 30 is a light-transmitting substrate similar or identical to the first substrate 10. First insulating layer 34 is similar to or the same as first insulating layer 17. Filler material layer 38 is similar to or the same as filler material layer 25. In addition, the steps similar to those described above will not be described in detail here.The main difference between this embodiment and the previous embodiment is that the steps of the forming method of this embodiment are different from those of the previous embodiment.

[0074] As shown in Figure 25, a first substrate 30 is provided. As shown in Figure 26, in one embodiment, a first debond layer 31 is disposed on the first substrate 30. As shown in Figure 26, an adhesive layer 32 is disposed on the first debond layer 31, and multiple micro LED dies 33 are arranged side by side on the adhesive layer 32. As shown in Figure 27, in these embodiments, the light-emitting surface 33A of the micro LED die 33 faces the first substrate 30, and the electrode surface 33B faces the opposite side of the first substrate 30. That is, the light-emitting surface 33A of the micro LED die 33 faces and contacts the adhesive layer 32.

[0075] 28, a portion of the adhesive layer 32 is removed. Specifically, for example, the portion of the adhesive layer 32 that is not covered by the micro LED die 33 can be removed by an etching removal process.

[0076] As shown in FIG. 29 , a first insulating layer 34 is disposed on the electrode surface 33B of the micro LED die 33, and the first insulating layer 34 is in direct contact with the electrode surface 33B and the side surface 33C of the micro LED die 33, and exposes the electrode 330 of the micro LED die 33. In one embodiment, the first insulating layer 34 is continuous and uninterrupted, surrounding the side surface 33C of the micro LED die 33. In one embodiment, when the thicknesses of the micro LED dies 33 are different, for example, the thicknesses of the red micro LED die, the blue micro LED die, and the green micro LED die are different, a first insulating layer 34 is formed on the micro LED die 33, and the depths of the holes 340 exposing the electrodes 330 of the micro LED die 33 are made different. In one embodiment, any two of the red, blue, and green LEDs in the micro LED die 13 have different thicknesses. For example, the blue LED and the green LED have the same thickness, but the blue LED and the red LED have different thicknesses, and the green LED and the LED have different thicknesses. The redistribution layer, which will be described later, can make the light-emitting surfaces 13A of these micro LED dies 13 with different thicknesses uniform to maintain a desirable display effect. In one embodiment, the thickness of the blue LED and the green LED is greater than the thickness of the red LED.

[0077] 30 , a plurality of re-distribution layers 35 are disposed on the first insulating layer 34, and the re-distribution layers 35 pass through the first insulating layer 34 and are electrically connected to the electrodes 330 on the electrode surfaces 33B of the micro LED dies 33, respectively. Similar to the above, the extending lengths (or thicknesses) of the vertical connecting portions 35A of the re-distribution layers 35 are different, thereby making the light-emitting surfaces 33A of the micro LED dies 33 substantially coplanar, and making the horizontal connecting portions 35B of the re-distribution layers 35 corresponding to the respective micro LED dies 33 substantially coplanar.

[0078] In one embodiment, when the thickness of the micro LED die 33 is the same, for example, the thickness of the red LED, blue LED, and LED die is the same.

[0079] In one embodiment, when the thicknesses of the micro LED dies 33 are the same, a first insulating layer 34 is formed on the micro LED dies 33, and the depths of the holes 340 exposing the electrodes 330 of the micro LED dies 33 are the same. A plurality of re-distribution layers 35 are disposed on the first insulating layer 34, and the re-distribution layers 35 pass through the first insulating layer 34 and are electrically connected to the electrodes 330 on the electrode surfaces 33B of the micro LED dies 33, respectively. The extension lengths (or thicknesses) of the vertical connection portions 35A of the re-distribution layers 35 are the same. This makes the light-emitting surfaces 33A of the micro LED dies 33 substantially coplanar, and also makes the horizontal connection portions 35B of the re-distribution layers 35 corresponding to the respective micro LED dies 33 substantially coplanar.

[0080] 31, the second insulating layer 36 is disposed on the first insulating layer 34, and the second insulating layer 36 covers the re-distribution layer 35. In other words, the re-distribution layer 35 is embedded in the second insulating layer 36.

[0081] 32, a plurality of conductive elements 37 are disposed on the first insulating layer 34 and the re-distribution layer 35, and the conductive elements 37 are electrically connected to the re-distribution layer 35. In one embodiment, the conductive elements 37 are metal posts, although the present disclosure is not limited thereto.

[0082] As shown in FIG. 33, a filler material layer 38 is placed on the second insulating layer 36, the filler material layer 38 surrounding and completely covering the conductive elements 37.

[0083] 34, a portion of filler material layer 38 is removed to expose the top surface of conductive element 37. For example, but not limited to, the filler material layer 38 may be removed by chemical mechanical polishing, etching, or any other suitable method, or a combination thereof. In one embodiment, after the top surface of conductive element 37 is exposed, the top surface of filler material layer 38 and conductive element 37 are flush with each other.

[0084] 35, the conductive pad 39 is disposed on the conductive element 37, and the upper surface of the conductive pad 39 and the upper surface of the fill material layer 38 are on different planes. The conductive pad 39 is electrically connected to the conductive element 37. In one embodiment, the conductive pad 39 vertically covers the conductive element 37 and a portion of the fill material layer 38. That is, when viewed from above, the conductive pad 39 overlaps and is in direct contact with the conductive element 37, and an end or periphery of the conductive pad 39 overlaps and is in direct contact with a portion of the fill material layer 38. In one embodiment, the top area of ​​the conductive pad 39 is larger than the top area of ​​the conductive element 37. As a result, in a top view direction, the conductive pad 39 completely overlaps and is in direct contact with the conductive element 37, and two ends or the entire periphery of the conductive pad 39 overlap and are in direct contact with a portion of the filler material layer 38. Also referring to FIG. 39, FIG. 39 is a top view of a micro LED package structure according to some embodiments of the present invention, and FIG. 39 is a cross-sectional view taken along CC' in FIG. 38. In one embodiment, the number of conductive pads 39 is four, one of which is a common conductive pad 39 . In one embodiment, the shapes of the conductive pads 39 in the top view may be the same. In one embodiment, the shape of the conductive pads 39 in the top view may vary. In one embodiment, the common conductive pad 39 is square in shape and has one triangular notch, and the other non-common conductive pads 39 are square in shape. In one embodiment, the triangular notch of the common conductive pad 39 can be located at the upper left corner, upper right corner, lower left corner, or lower right corner of the square. In one embodiment, the common conductive pad 39 is square in shape and has two triangular notches.

[0085] In one embodiment, in the top view direction, the conductive pads 39 overlap the redistribution layer 35 . In one embodiment, in the top view direction, some micro LED dies 33 overlap with two conductive pads 39, for example, the arrangement manner is similar to that shown in Fig. 16, but the present disclosure is not limited thereto. It should be noted that although the embodiments of Figs. 1 to 22 do not specifically show conductive pads, the conductive pads of this embodiment can also be applied to the above-mentioned embodiments.

[0086] In one embodiment, the conductive pads 39 are or include a conductive material, such as, but not limited to, a metal, a metal compound, or other suitable conductive material, or a combination thereof. For example, the metal may be tin (Sn), copper (Cu), gold (Au), silver (Ag), nickel (Ni), indium (In), platinum (Pt), palladium (Pd), iridium (Ir), titanium (Ti), chromium (Cr), tungsten (W), aluminum (Al), molybdenum (Mo), magnesium (Mg), zinc (Zn), germanium (Ge), or an alloy thereof. For example, the metal compound may be tantalum nitride (TaN), titanium nitride (TiN), tungsten silicide (WSi2), indium tin oxide (ITO), etc.

[0087] 36, the first substrate 30 is turned over and removed. For example, depending on the type of first release layer 31, the first release layer 31 may be made to lose its adhesiveness by heating, UV light, laser, etc., and the first substrate 30 thereon may be removed.

[0088] 37, portions of the adhesive layer 32 and the first insulating layer 34 are removed to expose the light-emitting surface 33A of the micro LED die 33. The adhesive layer 32 and the first insulating layer 34 are removed by a removal process such as etching, polishing, or any other suitable method, or a combination thereof. After the adhesive layer 32 and the first insulating layer 34 are removed, the upper surface 34A of the first insulating layer 34 is flush with the light-emitting surface 33A, although the present disclosure is not limited thereto. In one embodiment, the adhesive layer 32 and a portion of the first insulating layer 34 are removed to ensure that the adhesive layer 32 on the light-emitting surface 33A is completely removed until the upper surface 34A of the first insulating layer 34 is lower than the light-emitting surface 33A. Under these circumstances, the upper surface 34A of the first insulating layer 34 contacts the side surface 33C of the micro-LED die 33. In one embodiment, the first insulating layer 34 is continuous and surrounds the side surface 33C of the micro LED die 33. The first insulating layer 34 is filled between the electrodes 330 of the micro LED die 33. Therefore, the first insulating layer 34 prevents the micro LED die 33 from falling off before the aforementioned process of removing the adhesive layer 32 and a portion of the first insulating layer 34. Also, after removing the adhesive layer 32 and a portion of the first insulating layer 34, the first insulating layer 34 fixes the micro LED die 33 in the micro LED package structure 1. As shown in Figure 38, a light-transmitting layer 40 is provided to cover the light-emitting surface 33A of the micro LED die 33 to form the micro LED package structure 1. In one embodiment, when the top surface 34A of the first insulating layer 34 is lower than the light-emitting surface 33A, the light-transmitting layer 40 can cover the light-emitting surface 33A and the side surface 33C of the micro-LED die 33. In one embodiment, the sides of the light-transmitting layer 40, the sides of the first insulating layer 34, the second insulating layer 36 and the filler material layer 38 are flush with each other. In one embodiment, the micro LED packaging structure 1 is a cube or a rectangular parallelepiped.

[0089] Figure 40 illustrates a display module according to some embodiments of the present invention. The micro LED package structure 1 is applied as a pixel unit in a display device. In one embodiment, the micro LED package structure 1 of the present invention is applied in a display module 2 and used as a pixel unit. As shown in Figure 38, the display module 2 includes the micro LED package structure 1 and a printed circuit board PCB. The micro LED package structure 1 is electrically connected to the printed circuit board PCB. In one embodiment, a bonding material electrically connects the micro LED package structure 1 and the printed circuit board PCB. In one embodiment, a packaging material EL is used to cover these micro LED packaging structures 1 to form a display module 2. In one embodiment, the material of the packaging material EL is similar to or the same as the material of the light-transmitting layers 14, 40, although the present disclosure is not limited in this respect. In one embodiment, the material of the packaging material is different from the material of the light-transmitting layers 14, 40, although the present disclosure is not limited in this respect. In one embodiment, the packaging material EL is a transparent material, although the present disclosure is not limited thereto.

[0090] It should be noted that although FIG. 40 shows a possible structure and arrangement of the display module 2, the present disclosure is not limited thereto. In other embodiments, the micro LED package structure 1 of the present invention can be applied in various display modules that are familiar to those skilled in the art. In one embodiment, the display module 2 of the present invention can be attached to display devices of various sizes.

[0091] 41 is a diagram illustrating a splicing display device according to some embodiments of the present invention. In one embodiment, the micro LED package structure 1 of the present invention can be applied in a display module 2, and multiple display modules 2 can be applied in multiple display devices. As shown in the figure, multiple display devices having multiple display modules 2 can be jointly applied to the splicing display device.

[0092] The components in this embodiment may be used in any combination as long as they are consistent with the spirit of the invention and do not conflict with it. Furthermore, the scope of protection of this disclosure is not limited to the manufacturing methods, devices, manufactures, compositions of matter, apparatuses, methods, and procedures that are limited to specific embodiments in the description. Those skilled in the art can understand from the contents of this disclosure that manufacturing methods, devices, manufactures, compositions of matter, apparatuses, methods, and procedures currently or in the future may be used based on this disclosure if they perform essentially equivalent functions or achieve essentially equivalent results in this embodiment. Therefore, the scope of protection of this disclosure includes the above-mentioned manufacturing methods, devices, manufactures, compositions of matter, apparatuses, methods, and procedures. Any embodiment or claim of this disclosure does not necessarily achieve all of the objectives, advantages, and / or features disclosed in this disclosure.

[0093] The above description outlines several embodiments to allow those skilled in the art to better understand the scope of the disclosed embodiments. It should be understood by those skilled in the art that other processes and structures can be designed or modified based on the disclosed embodiments to achieve the same objectives and advantages as the embodiments described herein. It should be understood by those skilled in the art that such equivalent processes and structures do not depart from the spirit and scope of the present disclosure, and various modifications, substitutions, and replacements may be made without violating the spirit and scope of the present disclosure. [Explanation of symbols]

[0094] 1 Micro LED package structure, 2 Display module, 10, 30 First substrate, 11, 31 First release layer, 12, 32 Adhesive layer, 13, 33 Micro LED die, 13A, 33A Light-emitting surface, 13B, 33B Electrode surface, 13C, 33C Side surface, 14 Light-transmitting layer, 14s2, 14s3 Roughened surface, 15 Second release layer, 16 Second substrate, 17, 34 First insulating layer, 18, 35 Redistribution layer, 18A, 35A Vertical connection portion, 18B, 35B Horizontal connection portion, 19, 36 Second insulating layer, 20, 20a, 20b, 24, 37 Conductive element, 21 Hard mask layer, 22 Third release layer, 23 Third substrate, 25, 38 Filler material layer, 26a, 26b, 26c Reflective structure, 39 Conductive pad, 40 Transparent layer, 130 electrode, 130A upper part, 130B lower part, 131 first reflective layer, 132 second reflective layer, 133 semiconductor stack layer, 140 sacrificial layer, 142 support frame, 160 mounting substrate, 170 adhesive layer, 330 electrode, 340 hole, A area, A-A', B-B', C-C' lines, EL package material, PCB printed circuit board, S1 first contact surface, S2 second contact surface, SP tin paste, t1, t2 thickness, w1 width.

Claims

1. A micro light emitting diode package structure, comprising: a first micro light-emitting diode die having an electrode, an electrode surface, a light-emitting surface, and a plurality of side surfaces, the electrode surface and the light-emitting surface facing each other, and the plurality of side surfaces being located between the electrode surface and the light-emitting surface, the electrode having an upper portion and a lower portion, and a step being provided between the upper portion and the lower portion; a light-transmitting layer disposed on the light-emitting surface; a first insulating layer provided so as to surround the plurality of side surfaces; a redistribution layer disposed on the electrode and extending along the upper portion, the lower portion, and the step portion.

2. 10. The micro light-emitting diode package structure according to claim 1, further comprising a second micro light-emitting diode die and a third micro light-emitting diode die disposed alongside the first micro light-emitting diode die.

3. 2. The micro light-emitting diode package structure of claim 1, wherein the redistribution layer includes a vertical connection and a horizontal connection, and the vertical connection penetrates the first insulating layer and is electrically connected to the first micro light-emitting diode die.

4. the first insulating layer has an upper surface; The micro light-emitting diode package structure of claim 1 , wherein the top surface is substantially coplanar with the light-emitting surface.

5. 4. The micro light-emitting diode package structure according to claim 3, further comprising a second insulating layer disposed below the first insulating layer and covering the re-distribution layer.

6. 6. The micro light-emitting diode packaging structure as claimed in claim 5, wherein the horizontal connector is disposed between the first insulating layer and the second insulating layer.

7. 4. The micro light emitting diode package structure according to claim 3, further comprising: a conductive element disposed below the redistribution layer and electrically connected to the redistribution layer.

8. A micro light emitting diode package structure, comprising: a light-transmitting substrate; a first micro light-emitting diode die disposed on the light-transmitting substrate, the first micro light-emitting diode die having an electrode, an electrode surface, a light-emitting surface and a plurality of side surfaces, the electrode surface and the light-emitting surface facing each other, the light-emitting surface facing the light-transmitting substrate, the electrode having an upper portion and a lower portion, and a step between the upper portion and the lower portion; a first insulating layer surrounding the plurality of sides of the first micro light emitting diode die; a redistribution layer disposed on the electrode and extending along the upper portion, the lower portion, and the step portion.

9. The micro light-emitting diode package structure of claim 8 , further comprising an adhesive layer in contact with the light-emitting surface.

10. 10. The micro light-emitting diode package structure of claim 9, further comprising a second insulating layer disposed below the first insulating layer and covering the re-distribution layer.

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