Display module and manufacturing method therefor

Abstract

This display module comprises: a substrate including a first pad and a common electrode pad; a light-emitting diode including a first electrode connected to the first pad, and a second electrode; a conductive connector, which is connected to the common electrode pad and is connected to a second electrode connected to the common electrode pad; an adhesive layer arranged on the substrate; and a conductive layer for connecting the second electrode to the conductive connector on the adhesive layer, wherein the second electrode of the light-emitting diode is positioned on the light-emitting diode side surface positioned between a light-emitting surface of the light-emitting diode and the light-emitting diode lower surface, which is opposite to the light-emitting surface, and the light-emitting surface of the light-emitting diode is exposed at the conductive layer, which encompasses the second electrode of the light-emitting diode.

Description

Display module and manufacturing method thereof

[0001] The present disclosure relates to a display module and a method for manufacturing the same.

[0002] Recently, light-emitting diode (LED) technology based on compound semiconductors such as GaN, GaAs, and GaP has been developing rapidly. Along with this technological advancement in LEDs, interest in LED display devices utilizing panel configuration technology that directly mounts (transfers) LEDs that emit light in the R (red), G (green), and B (blue) wavelength bands onto a circuit board has grown. In particular, miniaturization of LEDs is essential for outputting high-definition images from LED display devices, and thus, significant development infrastructure is being invested to perfect micro light-emitting diodes with an ultra-small size of 100 micrometers or less.

[0003] According to one aspect of the present disclosure, a display module may include a substrate including a first pad and a common electrode pad; a light emitting diode including a first electrode connected to the first pad and a second electrode; a conductive connector connected to the common electrode pad and connected to a second electrode connected to the common electrode pad; an adhesive layer on the substrate; and a conductive layer connecting the second electrode to the conductive connector on the adhesive layer; wherein the second electrode of the light emitting diode is located on a side of the light emitting diode that is located between a light emitting surface of the light emitting diode and a lower surface of the light emitting diode opposite the light emitting surface, and the light emitting surface of the light emitting diode is exposed from the conductive layer surrounding the second electrode of the light emitting diode.

[0004] According to one aspect of the present disclosure, a method for manufacturing a display module may include the steps of: providing an adhesive layer on a first surface of a substrate; transferring a light-emitting diode onto the adhesive layer; transferring a conductive connector onto the adhesive layer; thermally compressing the light-emitting diode and the conductive connector to the substrate so as to connect a first electrode of the light-emitting diode to a first pad of the substrate and a third electrode positioned below the conductive connector to a common electrode pad of the substrate; and forming a conductive layer on the adhesive layer so as to expose a light-emitting surface of the light-emitting diode and interconnect a second electrode of the light-emitting diode and a fourth electrode positioned at a side of the conductive connector.

[0005] According to one aspect of the present disclosure, a display module comprises: a substrate including a first pad and a common electrode pad; a light emitting diode including a first electrode connected to the first pad; a conductive connector connected to the common electrode pad; an adhesive layer on the substrate; and a conductive layer on the adhesive layer, the conductive layer being connected to a side surface of the light emitting diode, the side surface being between a light emitting surface of the light emitting diode and a lower surface of the light emitting diode opposite the light emitting surface, and the side surface of the light emitting diode being connected to the common electrode pad of the substrate by the conductive layer and the conductive connector.

[0006] The above and other aspects, features and advantages of specific embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings.

[0007] FIG. 1 is a front view showing a display module according to one embodiment of the present disclosure.

[0008] FIG. 2 is an enlarged view showing part A of a display module according to one embodiment of the present disclosure.

[0009] FIG. 3 is a cross-sectional view taken along the line B-B' shown in FIG. 2, showing a pixel according to one embodiment of the present disclosure.

[0010] FIG. 4 is a cross-sectional view showing a first micro light-emitting diode of a display module according to one embodiment of the present disclosure.

[0011] FIG. 5 is a cross-sectional view showing a first micro light-emitting diode of a display module according to one embodiment of the present disclosure.

[0012] FIGS. 6, 7 and 8 are drawings showing various shapes of a second electrode provided on a side of a first micro light-emitting diode according to an embodiment of the present disclosure.

[0013] FIGS. 9 and 10 are drawings illustrating a method for manufacturing a micro light-emitting diode according to one embodiment of the present disclosure.

[0014] FIG. 11 is a flowchart illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0015] FIGS. 12, 13, 14, 15, 16 and 17 are drawings illustrating a method for manufacturing a display module according to one embodiment.

[0016] FIGS. 18, 19 and 20 are drawings illustrating a method for manufacturing a display module according to an embodiment of the present disclosure.

[0017] FIGS. 21, 22, and 23 are drawings illustrating a method for manufacturing a display module according to an embodiment of the present disclosure.

[0018] FIGS. 24 and 25 are drawings illustrating a method for manufacturing a display module according to one embodiment of the present disclosure.

[0019] FIG. 26 is a drawing illustrating a method for manufacturing a display module according to one embodiment of the present disclosure.

[0020] FIGS. 27 and 28 are drawings illustrating a method for manufacturing a display module according to one embodiment of the present disclosure.

[0021] FIGS. 29, 30, and 31 are drawings illustrating a method for manufacturing a display module according to an embodiment of the present disclosure.

[0022] FIGS. 32, 33, and 34 are drawings illustrating a method for manufacturing a display module according to an embodiment of the present disclosure.

[0023] FIGS. 35, 36, and 37 are drawings illustrating a method for manufacturing a display module according to an embodiment of the present disclosure.

[0024] FIG. 38 is a cross-sectional view showing a pixel according to an embodiment of the present disclosure.

[0025] FIG. 39 is a block diagram illustrating a display device according to an embodiment of the present disclosure.

[0026] Non-limiting embodiments of the present disclosure are described below with reference to the accompanying drawings. However, it should be understood that this is not intended to limit the scope to specific embodiments, but rather encompasses various modifications, equivalents, and / or alternatives of one or more embodiments according to the present disclosure. In connection with the description of the drawings, similar reference numerals may be used for similar components.

[0027] In describing the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the present disclosure. Furthermore, one or more embodiments according to the present disclosure may be modified in various different forms, and the scope of the technical concepts of the present disclosure is not limited to the following embodiments. Rather, these embodiments are provided to further faithfully and completely convey the technical concepts of the present disclosure to those skilled in the art.

[0028] The terminology used in this disclosure is for the purpose of describing specific embodiments only and is not intended to limit the scope of the rights. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0029] In this disclosure, expressions such as “has,” “can have,” “includes,” or “may include” indicate the presence of a corresponding feature (e.g., a component such as a number, function, operation, or part), and do not exclude the presence of additional features.

[0030] In this disclosure, expressions such as "A or B," "at least one of A and / or B," or "one or more of A or / and B" can include all possible combinations of the listed items. For example, "A or B," "at least one of A and B," or "at least one of A or B" can all refer to cases where (1) only one A is included, (2) only one B is included, or (3) both A and B are included.

[0031] The expressions “first,” “second,” “first,” or “second,” etc., used in this disclosure can describe various components, regardless of order and / or importance, and are only used to distinguish one component from another, but do not limit the components.

[0032] The expression "configured to" as used in the present disclosure may be used interchangeably with, for example, "suitable for," "having the capacity to," "designed to," "adapted to," "made to," or "capable of." The term "configured to" may not necessarily mean only "specifically designed to" in terms of hardware.

[0033] In the present disclosure, a "module" or "part" performs at least one function or operation and may be implemented in hardware or software, or a combination of hardware and software. Furthermore, multiple "modules" or multiple "parts" may be integrated into at least one module and implemented as at least one processor, excluding any "modules" or "parts" that require specific hardware implementation.

[0034] Meanwhile, the various elements and areas in the drawings are schematically drawn. Therefore, the technical concept of the present disclosure is not limited by the relative sizes or spacing drawn in the attached drawings.

[0035] Hereinafter, one or more non-limiting embodiments according to the present disclosure will be described in detail with reference to the attached drawings so that a person having ordinary skill in the art to which the present disclosure pertains can easily practice the present disclosure.

[0036] FIG. 1 is a front view illustrating a display module (30) according to one or more embodiments of the present disclosure. Hereinafter, a plurality of light emitting diodes mounted on a substrate (50) of the display module (30) may be micro light emitting diodes having a size of 100 μm or less or 30 μm or less.

[0037] Referring to FIG. 1, a display module (30) may include a substrate (50) and a first micro LED (110), a second micro LED (120), and a third micro LED (130) arranged on the substrate (50). The first, second, and third micro LEDs (110, 120, 130) may form one pixel. Each of the first, second, and third micro LEDs (110, 120, 130) may be referred to as a sub-pixel. The substrate (50) may have a plurality of pixel areas provided in a roughly grid shape on a first surface (50a) of the substrate (50). Each of the plurality of pixel areas may be provided with one pixel.

[0038] The first, second, and third micro LEDs (110, 120, 130) may be arranged in a grid pattern with a constant pitch on the upper surface of the substrate (50). The size (width X length X height) of each of the first, second, and third micro LEDs (110, 120, 130) may be, for example, 30 μm X 30 μm X 10 μm or less. Here, the width X length may be the area of ​​the light-emitting surface (111, 121, 131) of each of the first, second, and third micro LEDs (110, 120, 130).

[0039] The horizontal and vertical lengths of the first, second, and third micro LEDs (110, 120, 130) may be the same, but are not limited thereto. The horizontal and vertical lengths of the first, second, and third micro LEDs (110, 120, 130) may not be the same. For example, the horizontal X vertical length of the first, second, and third micro LEDs (110, 120, 130) may be 30㎛ X 10㎛ or 10㎛ X 30㎛. For example, when the horizontal and vertical lengths of the first, second, and third micro LEDs (110, 120, 130) are 30㎛ X 30㎛ or less, the heights of the first, second, and third micro LEDs (110, 120, 130) may be configured to be approximately 10㎛ or less.

[0040] Fig. 2 is an enlarged view showing a portion A of a display module (30) according to an embodiment of the present disclosure. Fig. 3 is a cross-sectional view taken along the line B-B' shown in Fig. 2, showing pixels according to an embodiment of the present disclosure.

[0041] Referring to FIGS. 2 and 3, the first, second, and third micro LEDs (110, 120, 130) included in one pixel can emit light of different wavelength bands. For example, the first micro LED (110) can emit red light. The second micro LED (120) can emit green light. The third micro LED (130) can emit blue light.

[0042] The sizes of the first, second, and third micro LEDs (110, 120, 130) may all be substantially the same, but are not limited thereto. The sizes of the first, second, and third micro LEDs (110, 120, 130) may have different sizes depending on the wavelength band to which they are applied.

[0043] In the case of a pentile array, the sizes of the first, second, and third micro LEDs (110, 120, 130) including four micro LEDs in one pixel may have different sizes depending on the wavelength band to which they are applied. The first micro LED (110) emitting red light may have a first size. The third micro LED (130) emitting blue light may have a second size smaller than the first size. The second micro LED (120) emitting green light may have a third size smaller than the second size. There may be two second micro LEDs (120). In this case, a total of four micro LEDs may be included in one pixel.

[0044] The arrangement order of the first, second, and third micro LEDs (110, 120, 130) is described as being arranged from left to right, but is not limited thereto. For example, the first, second, and third micro LEDs (110, 120, 130) may be arranged sequentially from right to left. The second, third, and first micro LEDs (120, 130, 110) may be arranged sequentially from right to left.

[0045] Each of the first, second, and third micro LEDs (110, 120, 130) may include a first electrode (113, 123, 133) and a second electrode (115, 125, 135) electrically connected to a plurality of TFT circuits provided on the substrate (50). The first electrode (113, 123, 133) may be an anode electrode, and the second electrode (115, 125, 135) may be a cathode electrode.

[0046] The first electrode (113, 123, 133) may be provided on the lower surfaces (114, 124, 134) of the first, second, and third micro LEDs (110, 120, 130). Here, the 'lower surfaces (114, 124, 134)' of the first, second, and third micro LEDs (110, 120, 130) may be surfaces on the opposite side of the light-emitting surfaces (111, 121, 131) of the first, second, and third micro LEDs (110, 120, 130).

[0047] The second electrodes (115, 125, 135) may be provided on the side surfaces (112, 122, 132) of the first, second, and third micro LEDs (110, 120, 130). The second electrodes (115, 125, 135) may surround the side surfaces (112, 122, 132) of the first, second, and third micro LEDs (110, 120, 130) in a closed loop shape, as shown in FIG. 2. The second electrodes (115, 125, 135) may be electrically connected to the conductive layer (170).

[0048] The conductive layer (170) can be electrically connected to a conductive connector (140) that is connected to a common electrode pad (54) of the substrate (50). Accordingly, the second electrodes (115, 125, 135) can be electrically connected to the common electrode pad (54) of the substrate (50).

[0049] A conductive layer (170) may be applied to the upper surface of the adhesive layer (160). The conductive layer (170) may be cured to contact and electrically connect the second electrodes (115, 125, 135) of the first, second, and third micro LEDs (110, 120, 130) and the fourth electrode (145) of the conductive connector (140), respectively. The conductive layer (170) may include an ink, a paste, or a semi-cured film containing conductive particles. The conductive particles may include at least one of Ag, Au, Cu, In, Sn, Ni, Co, Cr, Fe, Mo, and graphene. The conductive layer (170) may be formed on the adhesive layer (160) by at least one of inkjet printing, spray coating, spin coating, and slot die coating.

[0050] The conductive connector (140) may have a third electrode (143) disposed on the lower surface (144) of the conductive connector (140). The third electrode (143) may be electrically connected to the common electrode pad (54) of the substrate (50). The conductive connector (140) may have a fourth electrode (145) disposed on the side surface (142) of the conductive connector (140). The fourth electrode (145) may be electrically connected to the conductive layer (170).

[0051] According to some embodiments, the conductive connector (140) may not include the third electrode (143) and the fourth electrode (145). In this case, the lower surface (144) of the conductive connector (140) may be directly electrically connected to the common pad (54) of the substrate (50), and the side surface (142) of the conductive connector (140) may be directly electrically connected to the conductive layer (170). In this case, the conductive connector (140) may be made of a material that can minimize electrical resistance (e.g., ohmic resistance) to the common pad (54) and the conductive layer (170).

[0052] A reflective layer (117, 127, 137) may be provided on the side surfaces (112, 122, 132) of the first, second, and third micro LEDs (110, 120, 130). In this case, the reflective layer (117, 127, 137) may be disposed on the lower side of the second electrode (115, 125, 135). The reflective layer (117, 127, 137) may be in contact with the second electrode (115, 125, 135), but is not limited thereto. For example, the upper portion of the reflective layer (117, 127, 137) and the lower portion of the second electrode (115, 125, 135) may be non-contacted by spacing them apart. In this way, the reflective layer (117, 127, 137) and the second electrode (115, 125 135) can be provided together on the side surfaces (112, 122, 132) of the first, second, and third micro LEDs (110, 120, 130).

[0053] The reflective layers (117, 127, 137) can reflect light emitted from the active layers (110c, 120c, 130c) of the first, second, and third micro LEDs (110, 120, 130) to the light-emitting surfaces (111, 121, 131). The reflective layers (117, 127, 137) can include a distributed Bragg reflector (DBR). The DBR can be deposited in the form of a thin film on the side surfaces (112, 122, 132) of the first, second, and third micro LEDs (110, 120, 130) by, for example, a method such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). The DBR may include a multilayer structure formed by alternately stacking high-refractive-index materials (e.g., TiO2, GaN) and low-refractive-index materials (e.g., SiO2, Al2O3). For example, the thickness of each layer of the DBR may be formed to correspond to 1 / 4 of a specific wavelength to be reflected. Accordingly, the DBR may satisfy the resonance condition by reflecting light of a specific wavelength through multiple layers, thereby improving reflectivity. The optical performance of the first, second, and third micro LEDs (110, 120, 130) may be improved by the reflective layer (117, 127, 137).

[0054] An adhesive layer (160) may be attached to a first surface (50a) of a substrate (50). The adhesive layer (160) may include, for example, an anisotropic conductive film (ACF) or an anisotropic conductive paste. The adhesive layer (160) may include a non-conductive resin layer (161) having adhesive properties (e.g., a polymer-based adhesive) and a plurality of conductive balls (163) (e.g., micro-conductive balls) uniformly arranged within the non-conductive resin layer (161).

[0055] The non-conductive resin layer (161) of the adhesive layer (160) can be heated by heat when the first, second, and third micro LEDs (110, 120, 130) are thermally compressed to the substrate (50). In this case, the first, second, and third micro LEDs (110, 120, 130) can be drawn inward from the surface of the non-conductive resin layer (161). When the non-conductive resin layer (161) is cured, the first, second, and third micro LEDs (110, 120, 130) can be firmly fixed to the substrate (50).

[0056] The non-conductive resin layer (161) can have a color with high light absorption (e.g., black or a black-based color). The non-conductive resin layer (161) can absorb external light (e.g., natural light or light emitted from indoor lights around the display module (30). Accordingly, the boundaries between adjacent micro LEDs are clearly defined, thereby reducing interference from ambient light sources or light reflection, thereby improving the screen contrast ratio and clarity of the display module (30). The non-conductive resin layer (161) can separate the light emitted from adjacent first, second, and third micro LEDs (110, 120, 130) from each other, thereby improving the spreading of the light to the adjacent micro LEDs.

[0057] The non-conductive resin layer (161) may be configured to be transparent. In this case, a black matrix may be provided on the non-conductive resin layer (161). The black matrix may be configured to surround the light-emitting surfaces (111, 121, 131) of the first, second, and third micro LEDs (110, 120, 130) so as not to obscure the light-emitting surfaces (111, 121, 131).

[0058] A plurality of conductive balls (163) of the adhesive layer (160) can electrically connect the first electrodes (113, 123, 133) of the first, second, and third micro LEDs (110, 120, 130) and the first, second, and third pads (51, 52, 53) of the substrate (50). The plurality of conductive balls (163) may be formed of an insulating material (e.g., synthetic resin, glass, ceramic) and a conductive metal (e.g., Au, Ag, Cu, Ni) coated on the surface of the insulating material, or may be formed of a carbon-based material such as graphene or carbon nanotubes. The conductive balls (163) may have a size of about 2 to 10 μm. The conductive balls (163) may allow current to flow only in the thickness direction of the adhesive layer (160) (e.g., the vertical direction of the film).

[0059] The substrate (50) may include a plurality of TFT (thin film transistor) circuits. The substrate (50) may include a first surface (50a) on which first, second, and third micro LEDs (110, 120, 130) of the substrate (50) are mounted, and a second surface (50b) of the substrate (50) opposite the first surface (50a). A power supply circuit for supplying power to the plurality of TFT circuits, a data driver, a gate driver, and a timing controller for controlling each drive driver may be disposed on the second surface (50b) of the substrate (50).

[0060] The TFT circuit may include a plurality of TFTs for driving the first, second, and third micro LEDs (110, 120, 130). A plurality of TFTs may be provided in one pixel area. The TFT circuit may be located on the inside of the substrate (50). For example, the TFT circuit may be formed in an area adjacent to the first surface (50a) of the substrate (50). However, the TFT circuit is not limited thereto, and may be manufactured in the form of a separate film and attached to the first surface (50a) of the substrate (50). The first, second, third, and fourth pads (51, 52, 53, 54) arranged on the first surface (50a) of the substrate (50) may be electrically connected to a plurality of TFTs included in the TFT circuit. The TFT is not limited to a specific structure or type. For example, TFT can be implemented as LTPS TFT (Low-temperature polycrystalline silicon TFT), oxide TFT, Si TFT (poly silicon, a-silicon), organic TFT, graphene TFT, etc. TFT circuit can only include P-type (or N-type) MOSFET (metal oxide semiconductor field effect transistor) in CMOS (complementary metal oxide semiconductor) process on Si wafer.

[0061] The first, second, and third micro LEDs (110, 120, 130) may have substantially the same overall structure, although they may emit different colors of light. Hereinafter, the structure of the first micro LED (110) will be described.

[0062] FIG. 4 is a cross-sectional view showing a first micro LED (110) of a display module (30) according to one embodiment of the present disclosure.

[0063] Referring to FIG. 4, the first micro LED (110) may include a semiconductor portion (SC), a first electrode (113), a second electrode (115), and a reflective layer (117).

[0064] The semiconductor portion (SC) may include an n-type semiconductor layer (110a), a p-type semiconductor layer (110b), and an active layer (110c). Each of the n-type semiconductor layer (110a) and the p-type semiconductor layer (110b) may be implemented with a compound semiconductor of group III-V, group II-VI, etc. For example, each of the n-type semiconductor layer (110a) and the p-type semiconductor layer (110b) may be implemented with a nitride semiconductor. Each of the n-type semiconductor layer (110a) and the p-type semiconductor layer (110b) may be an n-GaN semiconductor layer and a p-GaN semiconductor layer, respectively. However, each of the n-type semiconductor layer (110a) and the p-type semiconductor layer (110b) is not limited thereto, and may be formed of various materials according to various characteristics required for the micro LED.

[0065] The n-type semiconductor layer (110a) is a semiconductor in which free electrons are used as carriers for transferring charges, and can be made by doping with an n-type dopant such as Si, Ge, Sn, or Te. The p-type semiconductor layer (110b) is a semiconductor in which holes are used as carriers for transferring charges, and can be made by doping with a p-type dopant such as Mg, Zn, Ca, or Ba.

[0066] The n-type semiconductor layer (110a) may include a light-emitting surface (111) that serves as a passage through which light generated in the active layer (110c) is emitted to the outside of the micro LED (110). The light-emitting surface (111) may be approximately flat and formed approximately parallel to the active layer (110c). In the present disclosure, the 'top surface of the semiconductor portion (SC)' and the 'light-emitting surface of the semiconductor portion (SC)' may be treated identically to the 'light-emitting surfaces (111) of the first, second, and third micro LEDs (110, 120, 130)' and may use the same reference numeral 111. The 'side surface of the semiconductor portion (SC)' may be treated identically to the 'side surface (112) of the first, second, and third micro LEDs (110, 120, 130)' and may use the same reference numeral 112.

[0067] The n-type semiconductor layer (110a) can be electrically connected to the second electrode (115). The second electrode (115) can be made of any one of Al, Ti, Cr, Ni, Pd, Ag, Ge, and Au, or an alloy thereof. Electrically conductive oxides such as ITO (indium tin oxide) and ZnO can be used for ohmic contacts between the second electrode (115) and the n-type semiconductor layer (110a).

[0068] The p-type semiconductor layer (110b) can be electrically connected to the first electrode (113). The first electrode (113) can be made of any one of Al, Ti, Cr, Ni, Pd, Ag, Ge, and Au, or an alloy thereof. Electrically conductive oxides such as ITO (indium tin oxide) and ZnO can be used for ohmic contacts between the first electrode (113) and the p-type semiconductor layer (110b).

[0069] The n-type semiconductor layer (110a), the p-type semiconductor layer (110b), and the active layer (110c) may be composed of various semiconductors having band gaps corresponding to specific regions within the spectrum. For example, the first micro LED (110) having an optical wavelength of 600-750 nm (red) may include one or more layers based on an AlInGaP-based semiconductor. The second micro LED (120) and the third micro LED (130), each having an optical wavelength of 500-570 nm (green) and an optical wavelength of 450-490 nm (blue), may include one or more layers based on an AlInGaN-based semiconductor.

[0070] The active layer (110c) may be positioned between the n-type semiconductor layer (110a) and the p-type semiconductor layer (110b). The active layer (110c) is a layer where electrons, which are carriers of the n-type semiconductor layer (110a), and holes, which are carriers of the p-type semiconductor layer (110b), meet. When electrons and holes meet in the active layer (110c), a potential barrier is formed as the electrons and holes recombine. In this case, when the electrons and holes transition to a lower energy level by overcoming the potential barrier according to the voltage applied to the first micro LED (110), light of a corresponding wavelength (e.g., red light) is emitted. The active layer (110c) may include a multi-quantum well structure, but the present disclosure is not limited thereto. For example, the active layer (110c) may include one of a single quantum well structure and a quantum dot structure. When the active layer (110c) includes a multi-quantum well structure, the well layer / barrier layer of the active layer (110c) may be formed in a structure such as InGaN / GaN, InGaN / InGaN, or GaAs / AlGaAs, but is not limited to such a structure. The number of quantum wells included in the active layer (110c) is also not limited to a specific number.

[0071] The side surface (112) of the semiconductor portion (SC) may be configured to be inclined from the light-emitting surface (111) (e.g., the upper surface) of the semiconductor portion (SC) toward the lower surface, which is the opposite side of the light-emitting surface (111) (e.g., the upper surface) of the semiconductor portion (SC). For example, the side surface (112) of the semiconductor portion (SC) may form an acute angle with the light-emitting surface (111) (e.g., the upper surface) of the semiconductor portion (SC). However, the present invention is not limited thereto, and the side surface (112) of the semiconductor portion (SC) may form an obtuse angle with the light-emitting surface (111) (e.g., the upper surface) of the semiconductor portion (SC).

[0072] A second electrode (115) and a reflective layer (117) may be provided together on the side surface (112) of the semiconductor portion (SC). As shown in FIG. 4, the second electrode (115) may be disposed on the upper side surface (112) of the semiconductor portion (SC), and the reflective layer (117) may be disposed on the lower side surface (112) of the semiconductor portion (SC). In this case, the height (H1) of the second electrode (115) may be substantially the same as the height (H2) of the conductive layer (170). The light-emitting surface (111) (e.g., the upper surface) of the semiconductor portion (SC) may be completely exposed without being covered by the second electrode (115) or the conductive layer (170).

[0073] The height (H1) of the second electrode (115) may be smaller than the height (H3) of the reflective layer (117). However, the present invention is not limited thereto, and the height (H1) of the second electrode (115) may be smaller than or equal to the height (H3) of the reflective layer (117). In this case, the height (H1) of the second electrode (115) may have a height that does not contact the active layer (110c) and the p-type semiconductor layer (110b).

[0074] FIG. 5 is a cross-sectional view showing a first micro LED (110') of a display module (30) according to one embodiment of the present disclosure.

[0075] Referring to FIG. 5, the first micro LED (110') may have a second electrode (115') and a reflective layer (117') covering a side surface (112') of the first micro LED (110'). The height (H1') of the second electrode (115') may be different from the height (H2') of the conductive layer (170'). For example, the height (H1') of the second electrode (115') may be smaller than the height (H2') of the conductive layer (170'). In this case, the upper end of the second electrode (115') may be located at a position lower by a constant distance (G) from the light-emitting surface (111') of the first micro LED (110'). The upper surface of the conductive layer (170') may be at substantially the same height as the light-emitting surface (111') of the first micro LED (110'). The upper end of the second electrode (115') may be covered by a conductive layer (170'). As shown in FIG. 5, even when the height (H1') of the second electrode (115') is different from the height (H2') of the conductive layer (170'), the light-emitting surface (111') of the first micro LED (110') may be completely exposed without being covered by the conductive layer (170').

[0076] FIGS. 6, 7, and 8 are drawings showing various shapes of a second electrode provided on a side of a first micro LED according to an embodiment of the present disclosure.

[0077] Referring to FIG. 6, the first micro LED (110-1) may be formed of a plurality of second electrodes (115-1) provided on the side surface (112-1). For example, the second electrode (115-1) may include first, second, third, and fourth portions (115a-1, 115b-1, 115c-1, 115d-1) (e.g., each portion may be an 'electrode') arranged at the first, second, third, and fourth corners (C1, C2, C3, C4) of the light-emitting surface (111-1), respectively. In this case, the first, second, third, and fourth portions (115a-1, 115b-1, 115c-1, 115d-1) may be arranged symmetrically with respect to the center of the light-emitting surface (111-1). According to one embodiment, a plurality of second electrodes (115-1) may be collectively referred to as a second electrode (115).

[0078] Referring to FIG. 7, the first micro LED (110-2) may be formed with a plurality of second electrodes (115-2) provided on the side surface (112-2). For example, the second electrode (115-2) may include first and second portions (115a-2, 115b-2) (e.g., each portion may be an 'electrode') respectively disposed at the first corner (C1) and the fourth corner (C4) diagonally disposed with respect to the first corner (C1) among the first, second, third, and fourth corners (C1, C2, C3, C4) of the light-emitting surface (111-2). In this case, the first portion (115a-2) may be formed to have a constant length toward the second and third corners (C2, C3) adjacent to the first corner (C1) of the light-emitting surface (111-2). The second portion (115b-2) may be formed to have a constant length toward the second and third corners (C2, C3) adjacent to the fourth corner (C4) of the light-emitting surface (111-2). The first and second portions (115a-2, 115b-2) of the second electrode (115-2) may be arranged diagonally symmetrically with respect to each other. According to one embodiment, a plurality of second electrodes (115-2) may be collectively referred to as a second electrode (115).

[0079] Referring to FIG. 8, the first micro LED (110-3) may be formed of a plurality of second electrodes (115-3) provided on the side surface (112-3). For example, the second electrode (115-3) may include first and second portions (115a-3, 115b-3) respectively disposed on first and second sides (S1, S2) facing each other of the light-emitting surface (111-3). The first and second portions (115a-3, 115b-3) of the second electrode (115-3) may be disposed symmetrically with respect to the horizontal center axis of the light-emitting surface (111-3) parallel to the X-axis of FIG. 8. According to one embodiment, the plurality of second electrodes (115-3) may be collectively referred to as a second electrode (115).

[0080] FIGS. 9 and 10 are drawings illustrating a method for manufacturing a micro LED according to an embodiment of the present disclosure.

[0081] Referring to FIG. 9, a plurality of micro LEDs (e.g., a first micro LED (110), a second micro LED (120), and a third micro LED (130)) may be epitaxially grown on an epitaxial substrate (300). The epitaxial substrate (300) may be, for example, a sapphire (Al2O3) substrate. A buffer layer (310) may be formed on the epitaxial substrate (300) to resolve lattice mismatch between the epitaxial substrate (300) and the epitaxial layer (330). The buffer layer (310) may be an aluminum nitride (AlN) or GaN buffer layer. The epitaxial layer (330) may be a semiconductor portion (SC) that is a gallium nitride (GaN)-based compound semiconductor.

[0082] An epitaxial layer (330) is grown on a buffer layer (310). The epitaxial layer (330) can be used as a semiconductor portion (SC) of the first micro LED (110). The epitaxial layer (330) is formed of n-type doped GaN and can include an n-type semiconductor layer (110a) grown on the buffer layer (310) using a dopant such as silicon (Si). The n-type semiconductor layer (110a) can be performed by a method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The epitaxial layer (330) can include an active layer (110c) grown on the n-type semiconductor layer (110a). The active layer (110c) may be formed of, for example, indium gallium nitride (InGaN) and may have a multi-layer quantum well structure. The quantum well structure may form a thin InGaN layer between GaN barrier layers. The wavelength of the emitted light may be controlled by adjusting the indium composition of the InGaN. In this case, the active layer (110c) may obtain light emission characteristics of a desired wavelength by adjusting growth conditions (e.g., temperature, pressure, precursor concentration). The active layer (110c) may emit light of one color (e.g., red, green, blue) depending on the light emission characteristics of the wavelength. The epitaxial layer (330) may include a p-type semiconductor layer (110b) grown on the active layer (110c). The p-type semiconductor layer (110b) may be formed of p-type doped GaN using a dopant such as magnesium (Mg). The p-type semiconductor layer (110b) can supply holes so that electrons and holes generated in the active layer (110c) can recombine.

[0083] After surface treatment of the upper surface of the p-type semiconductor layer (110b) (e.g., the side opposite to the side in contact with the active layer (110c)), a first electrode (113) is deposited on the upper surface of the p-type semiconductor layer (110b).

[0084] In order to use the epitaxial layer (330) as a plurality of micro LEDs, an isolation process is performed to form a semiconductor portion (SC) of a certain size. In this case, the side surface (112) of the semiconductor portion (SC) may be formed to form an acute angle with respect to the light-emitting surface (111). A reflective layer (117) is deposited on the side surface (112) of the semiconductor portion (SC). In this case, the reflective layer (117) may be located on the lower portion of the side surface (112) of the semiconductor portion (SC) (e.g., an area adjacent to the first electrode (113) among the entire area of ​​the side surface (112) of the semiconductor portion (SC)).

[0085] Referring to FIG. 10, for example, a plurality of semiconductor portions (SC) are separated from an epi substrate (300) through a dicing process. The plurality of semiconductor portions (SC) may be arranged at regular intervals so that a first electrode (113) is attached to an adhesive layer (410) on a first carrier substrate (400).

[0086] A second electrode (115) is deposited on the upper portion of the side surface (112) of the semiconductor portion (SC) (e.g., an area adjacent to the light-emitting surface (112)). The second electrode (115) may be formed in the last step of the manufacturing process of the first, second, and third micro LEDs (110, 120, 130).

[0087] The first, second, and third micro LEDs (110, 120, 130) arranged on the first carrier substrate (400) are transferred to the second carrier substrate (450) before being transferred to the substrate (50). The first, second, and third micro LEDs (110, 120, 130) transferred to the second carrier substrate (450) can have their light-emitting surfaces (112, see FIG. 12) attached to the adhesive layer (470, see FIG. 12) of the second carrier substrate (450).

[0088] FIG. 11 is a flowchart illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure. FIGS. 12, 13, 14, 15, 16, and 17 are drawings illustrating a method for manufacturing a display module according to one embodiment.

[0089] The second carrier substrate (450) is placed on the upper side of the substrate (50). The carrier substrate (450) and / or the substrate (50) are moved to align the first, second, and third micro LEDs (110, 120, 130) of the second carrier substrate (450) to correspond to the first pads (51, 52, 53) of the substrate (50).

[0090] Referring to FIG. 12, a laser beam (L) is irradiated onto the second carrier substrate (450) to transfer the first, second, and third micro LEDs (110, 120, 130) arranged on the second carrier substrate (450) to the substrate (50) (operation 1101 of FIG. 11).

[0091] The method of transferring the first, second, and third micro LEDs (110, 120, 130) onto the substrate (50) is not limited to the laser transfer method, and a pick and place method, a transfer printing method, a roll-to-roll transfer method, and an electrostatic transfer method can be applied. The pick and place transfer method is a method of picking up individual micro LEDs using a mechanical arm (e.g., a robot arm) or a vacuum suction device and transferring them to a desired location. When the pick and place transfer method is used, the first, second, and third micro LEDs (110, 120, 130) can be transferred from the first carrier substrate (400) to the substrate (50) without going through the second carrier substrate (450). The transfer printing method is a method of transferring all or a plurality of micro LEDs at once using a substrate on which micro LEDs are arranged, and a flexible medium such as a silicone rubber pad or a polymer film is used to separate the micro LEDs from the carrier substrate and then transfer them to the substrate. The roll-to-roll transfer method is a method of transferring micro LEDs to a substrate (50) by winding and unwinding a flexible carrier substrate into a roll shape through a roller. The electric field transfer method is a method of picking up micro LEDs by controlling the strength of an electric field and transferring them to a substrate (50).

[0092] Referring to FIG. 13, the first, second, and third micro LEDs (110, 120, 130) may be separated from the second carrier substrate (450) and attached to an adhesive layer (160) of the substrate (50). The adhesive layer (160) may include, for example, an anisotropic conductive film (ACF) or an anisotropic conductive paste. The adhesive layer (160) may include a non-conductive resin layer (161) having adhesive properties (e.g., a polymer-based adhesive) and a plurality of conductive balls (163) (e.g., micro-conductive balls) uniformly arranged within the non-conductive resin layer (161).

[0093] Referring to FIG. 14, when a plurality of micro LEDs are transferred to a defined position of the substrate (50) (e.g., a position corresponding to the first pad (51, 52, 53)), a conductive connector (140) is transferred to a defined position of the substrate (50) (e.g., a position corresponding to the common electrode pad (54)) (operation 1102 of FIG. 11).

[0094] Referring to FIG. 15, the first, second, and third micro LEDs (110, 120, 130) and the conductive connector (140) are thermally compressed toward the substrate (50) by the pusher (500) (operation 1103 of FIG. 11). In this case, the substrate (50) may be heated by a heater built into a stage supporting the substrate (50) and / or a heater built into the pusher (500). As the substrate (50) is heated, the non-conductive resin layer (161) of the adhesive layer (160) may be transformed into a liquid or jelly form. The first, second, and third micro LEDs (110, 120, 130) and the conductive connector (140) may be drawn into the non-conductive resin layer (161) by the pressure of the pusher (500).

[0095] The first, second and third micro LEDs (110, 120, 130) can be electrically connected to the first pad (51, 52, 53) of the substrate (50) by at least one conductive ball (163). The conductive connector (140) can be electrically connected to the common electrode pad (54) of the substrate (50) by at least one conductive ball (163). The first, second and third micro LEDs (110, 120, 130) and the conductive connector (140) can be physically firmly fixed to the substrate (50) as the non-conductive resin layer (161) is cured.

[0096] The upper surface of the non-conductive resin layer (161) may be positioned at a height approximately corresponding to the upper end of the reflective layer (117). In this case, the second electrodes (115, 125, 135) of the first, second, and third micro LEDs (110, 120, 130) may be exposed without being covered by the non-conductive resin layer (161).

[0097] Referring to FIG. 16, low-viscosity liquid ink (171) containing a conductive member (e.g., conductive particles) is applied to the upper surface of the adhesive layer (160) through a nozzle (600). The low-viscosity liquid ink (171) can fill the space between the first, second, and third micro LEDs (110, 120, 130) protruding from the upper surface of the non-conductive resin layer (161) and the conductive connector (140).

[0098] Referring to FIG. 17, a low-viscosity liquid ink (171) may be cured to form a conductive layer (170) (operation 1104 of FIG. 11). The conductive layer (170) may be electrically connected to the second electrodes (115, 125, 135) of the first, second, and third micro LEDs (110, 120, 130) and the fourth electrode (145) of the conductive connector (140), respectively.

[0099] The light-emitting surfaces (111, 121, 131) of the first, second, and third micro LEDs (110, 120, 130) can be fully exposed without being covered by the conductive layer (170). When a transparent electrode is formed on the light-emitting surface of the micro LED, the light transmittance of the transparent electrode is low, which may result in loss of brightness, and power consumption may be increased to compensate for the loss of brightness. According to an embodiment of the present disclosure, the micro LED can improve the reduction in brightness due to the transparent electrode since the light-emitting surface is fully exposed without being covered by a configuration such as a transparent electrode, and power consumption can be improved because there is no need to increase power to compensate for the reduction in brightness.

[0100] The connection between the first electrodes (113, 123, 133) of the first, second, and third micro LEDs (110, 120, 130) and the first pads (51, 52, 54) of the substrate (50), and the connection between the third electrode (143) of the conductive connector (140) and the common electrode pad (54) of the substrate (50) may be made by an anisotropic conductive film or an anisotropic conductive paste, but is not limited thereto, and may be made by the embodiments described with reference to FIGS. 18 to 23 below.

[0101] FIGS. 18, 19 and 20 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0102] Referring to FIG. 18, three first pads (51-4, 52-4, 53-4) and a common electrode pad (54-4) may be provided on the substrate (50-4). The three first pads (51-4, 52-4, 53-4) and one common electrode pad (54-4) may be configured to correspond to one pixel. The substrate (50) may include a plurality of first pads (51-4, 52-4, 53-4) and a plurality of common electrode pads (54-4) corresponding to a plurality of pixels.

[0103] An adhesive layer (160-4) covering the first pads (51-4, 52-4, 53-4) and the common electrode pad (54-4) may be applied to the upper surface of the substrate (50-4). The adhesive layer (160-4) may be a non-conductive film (NCF). The adhesive layer (160-4) may have a black or black-based color to absorb external light and improve the mixing of lights emitted from the first, second, and third micro LEDs (110-4, 120-4, 130-4).

[0104] Referring to Fig. 19, the first pad (51-4) may be provided with a plurality of contact protrusions (51a-4) on the upper surface. The plurality of contact protrusions (51a-4) may be formed integrally with the first pad (51-4) and may have elasticity. The plurality of contact protrusions (51a-4) may protrude from the upper surface of the first pad (51-4) at a constant height (e.g., about 1 to 3 μm). The plurality of contact protrusions (51a-4) may be uniformly arranged on the upper surface of the first pad (51-4) at a constant interval from each other. The remaining first pads (52-4, 53-4) and the common electrode pad (54-4) may each include a plurality of contact protrusions (52a-4, 53a-4, 54a-4) similar to the first pad (51-4).

[0105] Referring to FIG. 20, the first, second, and third micro LEDs (110-4, 120-4, 130-4) and the conductive connector (140-4) transferred onto the adhesive layer (160-4) of the substrate (50-4) can be thermally compressed. The first, second, and third micro LEDs (110-4, 120-4, 130-4) and the conductive connector (140-4) can be introduced into the adhesive layer (160-4) while being pressed toward the substrate (50-4) by the pusher (500-4).

[0106] A plurality of contact protrusions (51a-4, 52a-4, 53a-4) of the first pads (51-4, 52-4, 53-4) contact the first electrodes (113-4, 123-4, 133-4) of the first, second, and third micro LEDs (110-4, 120-4, 130-4). A plurality of contact protrusions (54a-4) of the common electrode pad (54-4) contact the third electrode (143-4) of the conductive connector (143-4).

[0107] In this case, the contact area of ​​the plurality of contact protrusions (51a-4, 52a-4, 53a-4) of the first pads (51-4, 52-4, 53-4) with the first electrodes (113-4, 123-4, 133-4) of the first, second, and third micro LEDs (110-4, 120-4, 130-4) may increase as they are deformed by pressure. The connectivity may be improved as the plurality of contact protrusions (51a-4, 52a-4, 53a-4) of the first pads (51-4, 52-4, 53-4) are brought into close contact with the first electrodes (113-4, 123-4, 133-4) of the first, second, and third micro LEDs (110-4, 120-4, 130-4) due to elasticity.

[0108] The contact area of ​​the plurality of contact protrusions (54a-4) of the common electrode pad (54-4) with the third electrode (143-4) of the conductive connector (143-4) can increase as they are deformed by pressure. The connectivity can be improved as the plurality of contact protrusions (54a-4) of the common electrode pad (54-4) are brought into close contact with the third electrode (143) of the conductive connector (140-4) due to elasticity.

[0109] FIGS. 21, 22 and 23 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0110] Referring to FIG. 21, the first pads (51-5, 52-5, 53-5) and the common electrode pad (54-5) of the substrate (50-5) may have solder (161-5, 162-5, 163-5, 164-5) applied to the upper surfaces thereof, respectively. The solder (161-5, 162-5, 163-5, 164-5) may also be applied to the first electrodes (113-5, 123-5, 133-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the third electrode (143-5) of the conductive connector (140-5).

[0111] Referring to FIG. 22, the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the conductive connector (140-5) are transferred to the substrate (50-5). In this case, the first electrodes (113-5, 123-5, 133-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) can contact the solders (161-5, 162-5, 163-5) on the first pads (51-5, 52-5, 53-5) of the substrate (50-5). The third electrode (143-5) of the conductive connector (140-5) can contact the solders (143-5) on the common electrode pads (54-5) of the substrate (50-5).

[0112] By performing the reflow process, the first, second, and third micro LEDs (110-5, 120-5, 130-5) can be physically and electrically connected to the first pads (51-5, 52-5, 53-5) of the substrate (50-5) via solders (161-5, 162-5, 163-5). The third electrode (143-5) of the conductive connector (140-5) can be physically and electrically connected to the common electrode pad (54-5) of the substrate (50-5) via solders (143-5).

[0113] Referring to FIG. 23, an insulating layer (160-5) may be applied on the substrate (50-5). In this case, the insulating layer (160-5) may be filled between the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the conductive connector (140-5). The insulating layer (160-5) may be formed to a height that does not cover the second electrodes (115-5, 125-5, 135-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the fourth electrode (145-5) of the conductive connector (140-5). The insulating layer (160-5) may have a black or black-based color to absorb external light and improve the mixing of light emitted from the first, second, and third micro LEDs (110-5, 120-5, 130-5). The insulating layer (160-5) may be an NCF having adhesive properties.

[0114] The second electrodes (115-5, 125-5, 135-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the fourth electrode (145-5) of the conductive connector (140-5) can be firmly fixed on the substrate (50-5) as the insulating layer (160-5) is cured. The second electrodes (115-5, 125-5, 135-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the fourth electrode (145-5) of the conductive connector (140-5) can be electrically connected to the common electrode pad (54-5) of the substrate (50-5) by the conductive layer (170, see FIG. 3) formed on the insulating layer (160-5).

[0115] According to one embodiment of the present disclosure, the connection between the second electrodes (115-5, 125-5, 135-5) of the first, second and third micro LEDs (110-5, 120-5, 130-5) and the first pads (51-5, 52-5, 53-5) of the substrate (50-5) and the connection between the fourth electrode (145-5) of the conductive connector (140-5) and the common electrode pad (54-5) can be made by nanocarbon connection.

[0116] Nanocarbon connections can be implemented using nanoscale carbon-based materials (e.g., carbon nanotubes (CNTs), graphene) to connect the second electrodes (115-5, 125-5, 135-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) to the first pads (51-5, 52-5, 53-5) of the substrate (50-5) and the fourth electrode (145-5) of the conductive connector (140-5) to the common electrode pad (54-5).

[0117] Nanocarbon material can be produced in the form of ink and applied to the upper surface of the first pad (51-5, 52-5, 53-5) and the common electrode pad (54-5) of the substrate (50-5) by screen printing, inkjet printing, or dipping.

[0118] The nanocarbon material applied to the upper surface of each of the first pads (51-5, 52-5, 53-5) and the common electrode pad (54-5) can be aligned in a specific direction using an electric field or a magnetic field to strengthen the electrical connection between the second electrodes (115-5, 125-5, 135-5) of the first, second, and third micro LEDs (110-5, 120-5, 130-5) and the first pads (51-5, 52-5, 53-5) of the substrate (50-5) and the electrical connection between the fourth electrode (145-5) of the conductive connector (140-5) and the common electrode pad (54-5).

[0119] The conductive layer (170) connecting the second electrode (115, 125, 125) of the first, second, and third micro LEDs (110, 120, 130) and the fourth electrode (145) of the conductive connector (140) can be formed using conductive low-viscosity liquid ink (171), but is not limited thereto, and can be formed by the embodiments described with reference to FIGS. 24 to 37 below.

[0120] FIGS. 24 and 25 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0121] According to one embodiment of the present disclosure, a conductive member, for example, a conductive paste (171-6) applied on a substrate (50-6) can be formed into a conductive layer (170-6) by plasma etching.

[0122] Referring to FIG. 24, the upper surface of the adhesive layer (160-6) and the upper surfaces of the first, second, and third micro LEDs (110-6, 120-6, 130-6) and the conductive connector (140-6) can be coated with conductive paste (171-6). In this case, the light-emitting surfaces (111-6, 121-6, 131-6) of the first, second, and third micro LEDs (110-6, 120-6, 130-6) and the upper surface (141-6) of the conductive connector (140-6) can be covered with the conductive paste (171-6). The conductive paste (171-6) can also be replaced with a conductive film.

[0123] Referring to Fig. 25, after the conductive paste (171-6) is cured, the substrate (50-6) is placed in a vacuum chamber (520-6). After a reactive gas (e.g., CF4, SF6, O2) is injected into the vacuum chamber (520-6), a high-frequency current is used to turn the gas into a plasma state. The plasma generated within the vacuum chamber (520-6) may be composed of ionized particles. These particles may collide with the upper surface of the conductive paste (171-6). Accordingly, a reaction occurs depending on the chemical composition of the conductive paste (171-6), and the particles are chemically reacted to be converted into volatile compounds, which can then be removed by a vacuum pump.

[0124] Since plasma etching enables vertical and precise etching using a directional ion beam, a portion of the conductive paste (171-6) can be removed vertically from the upper surface of the conductive paste (171-6) toward the lower surface by a constant thickness. The upper portion of the conductive paste (171-6) corresponding to the depth corresponding to the light-emitting surfaces (111-6, 121-6, 131-6) of the first, second, and third micro LEDs (110-6, 120-6, 130-6) among the entire thickness of the conductive paste (171-6) can be removed.

[0125] By plasma etching, the light-emitting surfaces (111-6, 121-6, 131-6) of the first, second, and third micro LEDs (110-6, 120-6, 130-6) can be completely exposed. In this case, the upper surface (141-6) of the conductive connector (140-6) can also be exposed. In this way, the conductive paste (171-6) can be formed into the conductive layer (170-6) by plasma etching.

[0126] Even if the conductive paste (171-6) covering the upper surface (141-6) of the conductive connector (140-6) is not removed by plasma etching, the brightness of the first, second, and third micro LEDs (110-6, 120-6, 130-6) is not affected.

[0127] FIG. 26 is a drawing explaining a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0128] According to one embodiment of the present disclosure, a conductive paste (or conductive film) applied on a substrate (50-7) can be formed into a conductive layer (170-7) by laser etching.

[0129] The upper surface of the adhesive layer (160-7) and the light-emitting surfaces (111-7, 121-7, 131-7) of the first, second, and third micro LEDs (110-7, 120-7, 130-7) and the upper surface (141-7) of the conductive connector (140-7) can be coated with a conductive paste (or conductive film).

[0130] Referring to FIG. 26, a laser beam can be irradiated onto the conductive paste (or conductive film) covering the light-emitting surfaces (111-7, 121-7, 131-7) of the first, second, and third micro LEDs (110-7, 120-7, 130-7) and the upper surface (141-7) of the conductive connector (140-7). Accordingly, the conductive paste (or conductive film) covering the light-emitting surfaces (111-7, 121-7, 131-7) of the first, second, and third micro LEDs (110-7, 120-7, 130-7) and the upper surface (141-7) of the conductive connector (140-7) can be removed.

[0131] Even if the conductive paste (or conductive film) covering the upper surface (141-7) of the conductive connector (140-7) is not removed by the laser beam, it does not affect the brightness of the first, second, and third micro LEDs (110-7, 120-7, 130-7). Therefore, only the conductive paste (or conductive film) covering the light-emitting surfaces (111-7, 121-7, 131-7) of the first, second, and third micro LEDs (110-7, 120-7, 130-7) may be removed by the laser beam.

[0132] FIGS. 27 and 28 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0133] According to one embodiment of the present disclosure, a photosensitive conductive ink (171-8) applied on a substrate (50-8) can be formed into a conductive layer (170-8) through photolithography.

[0134] Referring to FIG. 27, the upper surface of the adhesive layer (160-8) and the light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8) and the upper surface (141-8) of the conductive connector (140-8) can be coated with a photosensitive conductive ink (171-8). After the coated photosensitive conductive ink (171-8) is heated to evaporate the solvent, the photosensitive conductive ink (171-8) can be cured at a constant temperature (e.g., about 90 to 100° C.) for a constant period of time to increase the viscosity of the photosensitive conductive ink (171-8) so that it can be attached to the substrate (50-8).

[0135] As a pretreatment step for removing a portion of the cured photosensitive conductive ink (171-8), a mask (700) having a plurality of openings (710) through which ultraviolet rays pass is placed on the upper side of the photosensitive conductive ink (171-8). In this case, the plurality of openings (710) of the mask (700) may be placed to correspond to an area to be used as the conductive layer (170-8) among the entire area of ​​the photosensitive conductive ink (171-8). The light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8) and the upper surface (141-8) of the conductive connector (140-8) may be covered by the mask (700).

[0136] A pattern is transferred to the photosensitive conductive ink (171-8) by irradiating the substrate (50-8) with ultraviolet rays through a mask (700). The photosensitive conductive ink (171-8) exposed to ultraviolet rays chemically changes. In this case, the photosensitive conductive ink (171-8) may correspond to a negative photoresist.

[0137] Referring to FIG. 28, a portion of the conductive ink (171-8) that has not been exposed to ultraviolet rays is removed by a developer. A portion of the photosensitive conductive ink (171-8) covering the light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8) and the upper surface (141-8) of the conductive connector (140-8) can be removed by the developer.

[0138] The photosensitive conductive ink (171-8) remaining on the substrate (50-8) can function as a conductive layer (170-8). The height of the conductive layer (170-8) can be slightly higher than the light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8). Due to the height difference between the conductive layer (170-8) and the light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8), the conductive layer (170-8) can improve the mixing of colors of the lights emitted from the first, second, and third micro LEDs (110-8, 120-8, 130-8).

[0139] Even if a portion of the photosensitive conductive ink (171-8) covering the upper surface (141-8) of the conductive connector (140-8) is not removed, the brightness of the first, second, and third micro LEDs (110-8, 120-8, 130-8) is not affected. Therefore, only the conductive ink (171-8) covering the light-emitting surfaces (111-8, 121-8, 131-8) of the first, second, and third micro LEDs (110-8, 120-8, 130-8) may be removed.

[0140] FIGS. 29, 30 and 31 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0141] According to one embodiment of the present disclosure, a photosensitive conductive ink (171-9) applied on a substrate (50-9) can be formed into a conductive layer (170-9) through photolithography.

[0142] Referring to FIG. 29, the light-emitting surfaces (111-9, 121-9, 131-9) of the first, second, and third micro LEDs (110-9, 120-9, 130-9) and the upper surface (141-9) of the conductive connector (140-9) can be patterned to be covered with a photoresist (800).

[0143] Referring to FIG. 30, the upper surface of the adhesive layer (160-9) and the photoresist (800) can be coated with a photosensitive conductive ink (171-9). After coating, the coated photosensitive conductive ink (171-9) can be cured before exposure.

[0144] As a pretreatment step for removing a portion of the cured photosensitive conductive ink (171-9), a mask (700, see FIG. 27) having a plurality of openings (710, see FIG. 27) through which ultraviolet rays pass is provided on the upper side of the photosensitive conductive ink (171-9). The light-emitting surfaces (111-9, 121-9, 131-9) of the first, second, and third micro LEDs (110-9, 120-9, 130-9) and the upper surface (141-9) of the conductive connector (140-9) can be covered by the mask (700).

[0145] A pattern is transferred to the photosensitive conductive ink 171-9 by irradiating the substrate (50-9) with ultraviolet rays through a mask (700). A portion of the photosensitive conductive ink (171-9) exposed to the ultraviolet rays is chemically changed. In this case, a portion of the photosensitive conductive ink (171-9) may correspond to a negative photoresist. A first development may be performed to remove a portion of the photosensitive conductive ink (171-9) exposed to the ultraviolet rays using a first developer. For example, a portion of the photosensitive conductive ink (171-9) may be removed by plasma etching or laser etching.

[0146] Referring to FIG. 31, a second development process can be performed to remove the photoresist (800) using a second developer. A portion of the photosensitive conductive ink (171-9) that was not removed from the photoresist (800) during the first development process may remain. This portion of the remaining photosensitive conductive ink (171-9) can be removed together with the photoresist (800) during the second development process. Accordingly, the light-emitting surfaces (111-9, 121-9, 131-9) of the first, second, and third micro LEDs (110-9, 120-9, 130-9) can be completely exposed. Even if the photosensitive conductive ink (171-9) or photoresist (800) covering the upper surface (141-9) of the conductive connector (140-9) is not removed, the brightness of the first, second, and third micro LEDs (110-9, 120-9, 130-9) is not affected. Therefore, only a portion of the photosensitive conductive ink (171-9) and the photoresist (800) covering the light-emitting surfaces (111-9, 121-9, 131-9) of the first, second, and third micro LEDs (110-9, 120-9, 130-9) may be removed.

[0147] FIGS. 32, 33, and 34 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0148] According to one embodiment of the present disclosure, a transparent electrode material (e.g., ITO, IZGO (Indium Zinc Gallium Oxide)) deposited on a substrate (50-10) can be formed into a conductive layer (170-10) through plasma etching.

[0149] Referring to FIG. 32, the light-emitting surfaces (111-10, 121-10, 131-10) of the first, second, and third micro LEDs (110-10, 120-10, 130-10) and the upper surface (141-10) of the conductive connector (140-10) can be patterned to be covered with a photoresist (810).

[0150] Referring to FIG. 33, the upper surface of the adhesive layer (160-10) and the photoresist (810) can be coated with a transparent electrode material (171-10).

[0151] Referring to FIG. 31, the transparent electrode material (171-10) covering the photoresist (810) can be removed by plasma etching. For example, the transparent electrode material (171-10) can also be removed by laser etching.

[0152] A development process can be performed to remove the photoresist (810) covering the light-emitting surfaces (111-10, 121-10, 131-10) of the first, second, and third micro LEDs (110-10, 120-10, 130-10) using a developing solution. Accordingly, the light-emitting surfaces (111-10, 121-10, 131-10) of the first, second, and third micro LEDs (110-10, 120-10, 130-10) can be completely exposed.

[0153] Even if the transparent electrode material (171-10) or photoresist (810) covering the upper surface (141-10) of the conductive connector (140-10) is not removed, the brightness of the first, second, and third micro LEDs (110-10, 120-10, 130-10) is not affected. Therefore, only the transparent electrode material (171-10) and photoresist (810) covering the light-emitting surfaces (111-10, 121-10, 131-10) of the first, second, and third micro LEDs (110-10, 120-10, 130-10) may be removed.

[0154] FIGS. 35, 36 and 37 are drawings illustrating a method for manufacturing a display module (30) according to one embodiment of the present disclosure.

[0155] Referring to FIG. 35, the first, second, and third micro LEDs (110-11, 120-11, 130-11) separated from the second carrier substrate (450, see FIG. 12) and laser-transferred to the substrate (50-11) may leave a residue (900) as part of the adhesive layer (470, see FIG. 12) on the light-emitting surface (111-11, 121-11, 131-11). According to one embodiment of the present disclosure, the residue (900) can be used in a pattern such as a photoresist (800, 810, see FIGS. 29 and 32). The residue (900) may be polyimide (PI).

[0156] Referring to FIG. 36, the upper surface of the adhesive layer (160-11) and the residue (900) can be coated with a transparent electrode material (171-11).

[0157] Referring to FIG. 37, the transparent electrode material (171-11) covering the residue (900) can be removed by plasma etching. For example, the transparent electrode material (171-11) can also be removed by laser etching.

[0158] The residue (900) covering the light-emitting surfaces (111-11, 121-11, 131-11) of the first, second, and third micro LEDs (110-11, 120-11, 130-11) can be removed through a descum process. The descum process can effectively decompose and remove polymer materials such as PI using oxygen plasma. Accordingly, the light-emitting surfaces (111-11, 121-11, 131-11) of the first, second, and third micro LEDs (110-11, 120-11, 130-11) can be completely exposed.

[0159] Even if a portion or residue (900) of the transparent electrode material (171-11) covering the upper surface (141-11) of the conductive connector (140-11) is not removed, the brightness of the first, second, and third micro LEDs (110-11, 120-11, 130-11) is not affected. Therefore, only the transparent electrode material (171-11) and residue (900) covering the light-emitting surfaces (111-10, 121-10, 131-10) of the first, second, and third micro LEDs (110-11, 120-11, 130-11) may be removed.

[0160] FIG. 38 is a cross-sectional view showing a pixel according to an embodiment of the present disclosure.

[0161] Referring to FIG. 38, the first, second, and third micro LEDs (110-12, 120-12, 130-12) mounted on the substrate (50-12) can have their side surfaces (112-12, 122-12, 132-12) of the first, second, and third micro LEDs (110-12, 120-12, 130-12) directly contact the conductive layer (170-12). In this case, the n-type semiconductor layers (110a-12, 120a-12, 130a-12) of the first, second, and third micro LEDs (110-12, 120-12, 130-12) can be electrically connected to the conductive layer (170-2). Accordingly, the first, second and third micro LEDs (110-12, 120-12, 130-12) may not include a second electrode (115, 125, 135), unlike the first, second and third micro LEDs (110, 120, 130) illustrated in FIG. 3.

[0162] The first, second, and third micro LEDs (110-12, 120-12, 130-12) can be formed by a process that omits the step of forming the second electrode, thereby simplifying the manufacturing process, thereby improving productivity and reducing manufacturing costs.

[0163] The conductive connector (140-12) can be electrically connected when the side surface (142-12) of the conductive connector (140-12) is in direct contact with the conductive layer (170-12). The conductive connector (140-12) can be made of a material that can minimize electrical resistance (e.g., ohmic resistance) to the conductive layer (170-12).

[0164] FIG. 39 is a block diagram showing a display device (10) according to one embodiment of the present disclosure.

[0165] Referring to FIG. 39, a display device (10) may include a display module (30) and a processor (40). The display module (30) may include a substrate (50) and a display driver integrated circuit (IC) (70) for controlling the driving of a plurality of micro light emitting diodes provided on the substrate (50).

[0166] The processor (40) may be implemented as a digital signal processor (DSP), a microprocessor, a graphics processing unit (GPU), an artificial intelligence (AI) processor, a neural processing unit (NPU), or a time controller (TCON) that processes a digital image signal. The processor (40) is not limited thereto, and may include one or more of a central processing unit (CPU), a micro controller unit (MCU), a micro processing unit (MPU), a controller, an application processor (AP), a communication processor (CP), or an ARM processor, or may be defined by the relevant terminology. The processor (40) may be implemented as a system on chip (SoC) or large scale integration (LSI) having a built-in processing algorithm, or may be implemented in the form of an application specific integrated circuit (ASIC), or a field programmable gate array (FPGA).

[0167] The processor (40) can control hardware or software components connected to the processor (40) by running an operating system or application program, and can perform various data processing and operations. In addition, the processor (40) can load commands or data received from at least one of the other components into volatile memory and process them, and store various data in non-volatile memory.

[0168] The display driver IC (70) may include an interface module (71), a memory (72) (e.g., a buffer memory), an image processing module (73), or a mapping module (74). The display driver IC (70) may receive, for example, image information including image data or an image control signal corresponding to a command for controlling image data, from a corresponding component of the display device (10) through the interface module (71). For example, according to one embodiment, the image information may be received from a processor (40) (e.g., a main processor (e.g., an application processor) or an auxiliary processor (e.g., a graphics processing unit) that operates independently of the function of the main processor).

[0169] The display driver IC (70) can communicate with the sensor module and the interface module (71). In addition, the display driver IC (70) can store at least a portion of the received image information in the memory (72), for example, in units of frames. The image processing module (73) can, for example, perform preprocessing or postprocessing (e.g., resolution, brightness, or size adjustment) on at least a portion of the image data based on the characteristics of the image data or the characteristics of the substrate (50). The mapping module (74) can generate a voltage value or a current value corresponding to the image data preprocessed or postprocessed through the image processing module (73). According to one embodiment, the generation of the voltage value or current value may be performed at least in part based on, for example, properties of the pixels of the substrate (50), for example, the arrangement of the pixels (RGB stripe or pentile structure), or the size of each of the sub-pixels. At least some of the pixels of the substrate (50) may be driven at least in part based on, for example, the voltage value or current value, so that visual information (e.g., text, an image, or an icon) corresponding to the image data may be displayed through the substrate (50).

[0170] The display driver IC (70) can transmit a driving signal (e.g., a driver driving signal, a gate driving signal, etc.) to the display based on image information received from the processor (40).

[0171] The display driver IC (70) can display an image based on an image signal received from the processor (40). For example, the display driver IC (70) can display an image by generating a driving signal for a plurality of sub-pixels based on the image signal received from the processor (40) and controlling the light emission of the plurality of sub-pixels based on the driving signal.

[0172] According to one embodiment of the present disclosure, the display module (30) may further include a touch circuit. The touch circuit may include a touch sensor and a touch sensor IC for controlling the same. The touch sensor IC may control the touch sensor to detect, for example, a touch input or a hovering input for a designated location on the substrate (50). For example, the touch sensor IC may detect a touch input or a hovering input by measuring a change in a signal (e.g., voltage, light quantity, resistance, or charge quantity) for a designated location on the substrate (50). The touch sensor IC may provide information (e.g., location, area, pressure, or time) regarding the detected touch input or hovering input to the processor (40). According to one embodiment, at least a portion of the touch circuit (e.g., the touch sensor IC) may be included as a part of the display driver IC (70), the substrate (50), or another component (e.g., a coprocessor) disposed externally to the display module (30).

[0173] According to one embodiment of the present disclosure, the pixel driving method of the display module (30) may be an AM (active matrix) driving method or a PM (passive matrix) driving method.

[0174] According to one embodiment of the present disclosure, a display device (10) may include a display module (30). The display module (30) may display various images. Here, the images may include still images and / or moving images. The display module (30) may display various images, such as broadcast content, multimedia content, etc. In addition, the display module (30) may also display a user interface and icons.

[0175] According to one embodiment of the present disclosure, a display device (10) may include a plurality of display modules (30) and a support substrate to which the plurality of display modules (30) are electrically connected. The display device (10) may be implemented as a large format display (LFD) in which a plurality of display modules (30) are arranged in a grid pattern on the support substrate.

[0176] Although the preferred embodiments of the present disclosure have been illustrated and described above, the present disclosure is not limited to the specific embodiments described above, and various modifications may be made by a person having ordinary skill in the art to which the present disclosure pertains without departing from the gist of the present disclosure as claimed in the claims, and such modifications should not be understood individually from the technical idea or prospect of the present disclosure.

Claims

1. In the display module, A substrate including a first pad and a common electrode pad; A light emitting diode comprising a first electrode connected to the first pad and a second electrode; A conductive connector connected to the common electrode pad and connected to a second electrode connected to the common electrode pad; An adhesive layer on the above substrate; a conductive layer connecting the second electrode to the conductive connector on the adhesive layer; The second electrode of the above light-emitting diode is, Located on the side of the light emitting diode between the light emitting surface of the light emitting diode and the lower surface of the light emitting diode opposite the light emitting surface, The light-emitting surface of the above light-emitting diode is A display module, exposed from the conductive layer surrounding the second electrode of the light-emitting diode.

2. In paragraph 1, A display module in which the level of the light-emitting surface of the light-emitting diode is the same as the level of the upper surface of the conductive layer.

3. In paragraph 1, The second electrode of the above light-emitting diode is, A display module positioned adjacent to the light-emitting surface of the above light-emitting diode.

4. In paragraph 1, The second electrode of the above light-emitting diode is, A display module comprising a closed loop shape surrounding the side of the light emitting diode.

5. In paragraph 1, The second electrode of the above light-emitting diode is, a first part at a first corner of the side of the light emitting diode; and a second portion at a second corner of the side of the light emitting diode; The second part is arranged diagonally with respect to the first edge, A display module wherein the first part and the second part are formed symmetrically to each other.

6. In paragraph 1, The second electrode of the above light-emitting diode is, a first part on the first side of the light emitting diode; and a second part on the second side of the light emitting diode; The second side faces the opposite side of the first side, A display module wherein the first part and the second part are symmetrical to each other.

7. In paragraph 1, The above adhesive layer is, A display module comprising an anisotropic conductive film having a black color.

8. In paragraph 1, The above adhesive layer is, Contains a non-conductive film having a black color, The above display module further includes a third electrode on the lower surface of the conductive connector, The first pad of the above substrate is, A plurality of first contact protrusions protruding from the upper surface of the first pad and elastically contacting the first electrode of the light-emitting diode, The common electrode pad of the above substrate is, A display module comprising a plurality of second contact protrusions protruding from the upper surface of the common electrode pad and elastically contacting the third electrode.

9. In paragraph 1, The first electrode of the light-emitting diode and the first pad of the substrate are connected by a first solder, The above display module further includes a third electrode on the lower surface of the conductive connector, A display module, wherein the third electrode and the common electrode pad of the substrate are connected by a second solder.

10. In paragraph 1, The first electrode of the light-emitting diode and the first pad of the substrate are connected by a first nano carbon material, The above display module further includes a third electrode on the lower surface of the conductive connector, A display module, wherein the third electrode and the common electrode pad of the substrate are connected by a second nanocarbon material.

11. In a method for manufacturing a display module, A step of providing an adhesive layer on a first surface of a substrate; A step of transferring a light-emitting diode onto the above adhesive layer; A step of transferring a conductive connector onto the above adhesive layer; A step of thermally compressing the light emitting diode and the conductive connector to the substrate so as to connect the first electrode of the light emitting diode to the first pad of the substrate and connect the third electrode located at the lower portion of the conductive connector to the common electrode pad of the substrate; and A method for manufacturing a display module, comprising: forming a conductive layer on the adhesive layer to expose the light-emitting surface of the light-emitting diode and interconnecting the second electrode of the light-emitting diode and the fourth electrode located on the side of the conductive connector.

12. In paragraph 11, The step of forming the above challenge layer is: providing a liquid conductive ink between the light emitting diode and the conductive connector; and A method for manufacturing a display module, comprising: a step of curing the liquid challenge ink.

13. In paragraph 11, The step of forming the above challenge layer is: A step of coating a conductive member on the light-emitting diode, the conductive connector and the adhesive layer; and A step of removing a conductive member on the light-emitting surface of the light-emitting diode to expose the light-emitting surface of the light-emitting diode; The above challenge absence is, A method for manufacturing a display module, comprising a conductive paste or a conductive film.

14. In paragraph 13, The step of removing the above challenge member is: A method for manufacturing a display module, comprising the step of removing a portion of the conductive member by one of plasma etching and laser etching.

15. In paragraph 13, The step of forming the above challenge layer is: A step of covering the light emitting diode, the conductive connector and the adhesive layer with a photosensitive conductive ink; and A method for manufacturing a display module, comprising: a step of removing a portion of the photosensitive conductive ink on the light-emitting surface of the light-emitting diode by photolithography to expose the light-emitting surface of the light-emitting diode.

Images