Display module and method of manufacturing the same

Abstract

A display module and a method of manufacturing the same are provided. The method of manufacturing can include forming an epitaxial film including a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer, attaching the epitaxial film to an intermediate substrate including a conductive material, patterning the epitaxial film to form a light emitting diode (LED), and coupling the LED to a driving circuit layer through the conductive material.

Description

TECHNICAL FIELD

[0001] Apparatuses and methods consistent with the present disclosure relate to a display module and a manufacturing method thereof, and more particularly, to a display module for micro light emitting diodes (LEDs) and a manufacturing method thereof. BACKGROUND

[0002] A light emitting diode (LED) is a semiconductor element that emits light when a voltage is applied thereto, and is widely used as a display device that displays an image and a light source of a general lighting device.

[0003] Recently, display devices, display panels, display modules, etc. using micro LEDs (μ-LEDs) or micro light emitting diodes as light sources in units of pixels or sub-pixels have been developed. Here, the micro LED can refer to a semiconductor light emitting element having a width, a length, and a height of 1 to 100 micrometers (μm).

[0004] Compared to a liquid crystal display (LCD) requiring a separate backlight unit, a micro LED display module (or a display panel) using a micro LED as a light source has better contrast, response time, and energy efficiency. In addition, the micro LED display module using a micro LED has advantages of less screen burn-in, longer lifespan, higher light emitting efficiency, brighter brightness, etc. than an organic LED (OLED) using an inorganic material.

[0005] Generally, in the case of a display module using a micro LED as a light source, the micro LED adopts a flip chip structure, and the flip chip structure requires bumps and pads to contact the micro LED and a thin film transistor (TFT) circuit board. The bump is used to align the height of the positive electrode (e.g., a positive contact metal and a negative contact metal) of the flip chip and to facilitate the connection of the contact metal of the flip chip with an external electrode (e.g., a contact metal of the circuit board). For this, the bump requires good adhesion between the final metal layer of the chip pad and the metal layer of the circuit board, and low resistance. In general, Au bump plating is mainly used as a material for the bump. For example, when a micro LED is transferred to a TFT circuit board through a stamp transfer process, anisotropic conductive film (ACF) is used. Here, the ACF serves as a bonding agent, and Ni particles contained in the ACF are to facilitate the connection of the contact metal of the micro LED chip with the contact metal of the TFT circuit board.

[0006] However, as the micro LED chip size is miniaturized, the gap between the positive electrodes (or the positive electrodes of the TFT substrate) becomes too narrow, and there is a problem of short circuiting due to the invasion of the Ni particles into the positive electrode area.

[0007] Further, bonding through ACF or bump welding requires a heat treatment process, and problems such as cracks and micro-LED misalignment occur in the bump according to the heat treatment process. Due to the above problems, the micro-LEDs can not emit light normally, resulting in defective pixels, which in turn results in a decrease in production yield of the display module. SUMMARY

[0008] Embodiments of the disclosure overcome the above disadvantages and other disadvantages not described above. Also, the disclosure does not require overcoming the above disadvantages, and embodiments of the disclosure can not overcome any of the problems described above.

[0009] According to an aspect of the disclosure, there is provided a method of manufacturing a display module, the method including: forming an epitaxial film including a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer; attaching the epitaxial film to an intermediate substrate including a conductive material; patterning the epitaxial film to form a light emitting diode (LED); and electrically connecting the LED to a driving circuit layer through the conductive material.

[0010] The connecting of the LED to the driving circuit layer can include attaching the intermediate substrate to the driving circuit layer formed on a substrate to electrically connect the first type semiconductor layer of the LED to the driving circuit layer through the conductive material and electrically connect the second type semiconductor layer of the LED to the driving circuit layer through the conductive material.

[0011] The LED can have a vertical structure, and the conductive material can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire.

[0012] The driving circuit layer can include a pixel circuit and a first electrode and a second electrode coupled to the pixel circuit to electrically connect the first electrode and the second electrode to the pixel circuit.

[0013] The method can further include forming a passivation element on a sidewall of the LED.

[0014] The connecting of the second type semiconductor layer of the LED to the driving circuit layer can include forming a transparent electrode along the passivation element, and electrically connecting the second type semiconductor layer of the LED to the second electrode of the driving circuit layer through the transparent electrode and the conductive material.

[0015] The method can further include forming a black matrix in an area between the LED and another LED on the intermediate substrate.

[0016] The intermediate substrate can further include an adhesive material, wherein the intermediate substrate is attached to the driving circuit layer by the adhesive material to electrically connect the first type semiconductor layer of the LED to the first electrode of the driving circuit layer through the conductive material.

[0017] The adhesive material can include at least one of an epoxy resin, a polyimide, or a phenol.

[0018] The method can further include forming a reflective electrode on a lower portion of the first-type semiconductor layer or an upper portion of the second-type semiconductor layer.

[0019] According to another aspect of the disclosure, a display module is provided, including: a substrate; a driving circuit layer disposed on the substrate, the driving circuit layer including a pixel circuit and a plurality of electrodes configured to be electrically connected to the pixel circuit, wherein the plurality of electrodes includes a first electrode and a second electrode; an intermediate substrate including a first conductive portion, a second conductive portion, and an adhesive portion disposed in different regions, respectively, the intermediate substrate being attached to the driving circuit layer by the adhesive portion; and a light emitting diode (LED) disposed on the intermediate substrate, wherein the plurality of electrodes includes the first electrode and the second electrode, the LED including a light emitting layer and a first-type semiconductor layer and a second-type semiconductor layer disposed on an upper portion and a lower portion of the light emitting layer, respectively, the first-type semiconductor layer being configured to be electrically connected to the first electrode through the first conductive portion, and the second-type semiconductor layer being configured to be electrically connected to the second electrode through the second conductive portion.

[0020] The LED can have a vertical structure.

[0021] The display module can further include a passivation element disposed on a sidewall of the LED.

[0022] The LED can further include a transparent electrode disposed along the passivation element, and the second-type semiconductor layer is configured to be electrically connected to the second electrode through the transparent electrode.

[0023] The display module can further include a black matrix disposed in a region between the LED and another LED on the intermediate substrate.

[0024] The transparent electrode can be the same material as the first conductive portion and the second conductive portion of the intermediate substrate.

[0025] Each of the first conductive portion and the second conductive portion can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire.

[0026] The adhesive portion can include at least one of an epoxy resin, a polyimide, or a phenol.

[0027] The display module can further include a reflective electrode disposed on a lower portion of the first-type semiconductor layer or an upper portion of the second-type semiconductor layer.

[0028] According to another aspect of the disclosure, a display apparatus is provided, including: a substrate; a drive circuit layer disposed on the substrate, the drive circuit layer including a pixel circuit, a first electrode, and a second electrode; an intermediate substrate including a first portion and a second portion having a conductive material and a third portion having an adhesive material, the intermediate substrate being attached to the drive circuit layer by the adhesive material in the third portion; a light emitting diode (LED) disposed on the intermediate substrate and having a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer, wherein the first type semiconductor layer is electrically connectable to the first electrode through the conductive material in the first portion, and wherein the second type semiconductor layer is electrically connectable to the second electrode through the conductive material in the second portion.

[0029] The display module can further include a first path configured to electrically connect the first electrode to the first type semiconductor layer of the LED through the conductive material in the first portion of the intermediate substrate.

[0030] The display module can further include a second path configured to electrically connect the second electrode to the second type semiconductor layer of the LED through the conductive material in the second portion of the intermediate substrate.

[0031] According to another aspect of the disclosure, a method of forming a display apparatus is provided, including: forming an epitaxial film including a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer; forming an intermediate substrate including a first portion and a second portion having a conductive material and a third portion having an adhesive material; attaching the epitaxial film to the intermediate substrate by the adhesive material in the third portion of the intermediate substrate; patterning the epitaxial film to form a light emitting diode (LED); and attaching the intermediate substrate to a drive circuit layer by the adhesive material in the third portion, the drive circuit layer including a pixel circuit, a first electrode, and a second electrode.

[0032] The method can further include forming a first path to electrically connect the first electrode to the first type semiconductor layer of the LED through the conductive material in the first portion of the intermediate substrate.

[0033] The method can further include forming a second path to electrically connect the second electrode to the second type semiconductor layer of the LED through the conductive material in the second portion of the intermediate substrate. BRIEF DESCRIPTION OF DRAWINGS

[0034] The above and / or other aspects of the disclosure will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0035] Figure 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0036] Figure 2 is a diagram for describing a display module according to an embodiment of the disclosure;

[0037] Figure 3 FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0038] Figure 4A FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0039] Figure 4B FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0040] Figure 5 FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0041] Figure 6A FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0042] Figure 6B FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0043] Figure 7A FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0044] Figure 7B FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0045] Figure 8A FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0046] Figure 8B FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0047] Figure 8C FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0048] Figure 9A FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0049] Figure 9B FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0050] Figure 9C FIG. 1 is a diagram for describing a display module according to an embodiment of the disclosure;

[0051] Figure 9DFIG. 1 is a diagram for describing an operation of bonding an epitaxial film onto an intermediate substrate according to an embodiment of the present disclosure;

[0052] Figure 10A FIG. 2 is a diagram for describing a patterning operation according to an embodiment of the present disclosure;

[0053] Figure 10B FIG. 3 is a diagram for describing a patterning operation according to an embodiment of the present disclosure;

[0054] Figure 10C FIG. 4 is a diagram for describing a patterning operation according to an embodiment of the present disclosure;

[0055] Figure 10D FIG. 5 is a diagram for describing a patterning operation according to an embodiment of the present disclosure;

[0056] Figure 10E FIG. 6 is a diagram for describing a patterning operation according to an embodiment of the present disclosure;

[0057] Figure 10F FIG. 7 is a diagram for describing a structure of a display module of a patterning method according to an embodiment of the present disclosure;

[0058] Figure 11A FIG. 8 is a diagram for describing an operation of forming a passivation element according to an embodiment of the present disclosure;

[0059] Figure 11B FIG. 9 is a diagram for describing an operation of forming a passivation element according to an embodiment of the present disclosure;

[0060] Figure 11C FIG. 10 is a diagram for describing an operation of forming a passivation element according to an embodiment of the present disclosure;

[0061] Figure 12A FIG. 11 is a diagram for describing an inspection method according to an embodiment of the present disclosure;

[0062] Figure 12B FIG. 12 is a diagram for describing an inspection method according to an embodiment of the present disclosure;

[0063] Figure 13A FIG. 13 is a diagram for describing an operation of bonding an intermediate substrate onto a substrate 10 according to an embodiment of the present disclosure;

[0064] Figure 13B FIG. 14 is a diagram for describing an operation of bonding an intermediate substrate onto a substrate 10 according to an embodiment of the present disclosure;

[0065] Figure 13C FIG. 15 is a diagram for describing an operation of bonding an intermediate substrate onto a substrate 10 according to an embodiment of the present disclosure;

[0066] Figure 13Dis a diagram for describing an operation of bonding an intermediate substrate to a driving circuit layer according to an embodiment of the disclosure;

[0067] Figure 13E is a diagram for describing an operation of bonding an intermediate substrate to a driving circuit layer according to an embodiment of the disclosure;

[0068] Figure 14A is a diagram for describing an operation of forming an electrode according to an embodiment of the disclosure;

[0069] Figure 14B is a diagram for describing an operation of forming an electrode according to an embodiment of the disclosure;

[0070] Figure 14C is a diagram for describing an operation of forming an electrode according to an embodiment of the disclosure;

[0071] Figure 14D is a diagram for describing an operation of forming an electrode according to an embodiment of the disclosure; and

[0072] Figure 15 is a diagram for describing an operation of forming a black matrix according to an embodiment of the disclosure. DETAILED DESCRIPTION

[0073] The disclosure aims to provide a display module and a manufacturing method thereof, solve various problems such as a defect rate, a non-light-emitting rate, and a yield reduction of a related art μ-LED process, and alleviate the limitations of a related art μ-LED structure.

[0074] In describing the disclosure, detailed descriptions of known functions or configurations related to the disclosure can be omitted, which can unnecessarily obscure the gist of the disclosure. Further, the following embodiments can be modified in various ways, and the scope and spirit of the disclosure are not limited to the following embodiments. Rather, the embodiments make the disclosure sufficiently and completely, and the embodiments are provided to fully convey the technical spirit of the disclosure to those skilled in the art.

[0075] It should be understood that the technology mentioned in the disclosure is not limited to the specific embodiments, but includes all modifications, equivalents, and / or alternatives according to the embodiments of the disclosure. Throughout the drawings, similar components will be denoted by similar reference numerals.

[0076] The expressions "first", "second", and the like used in the disclosure can mean various components regardless of the order and / or importance of the components, and are used only to distinguish one component from the other components and do not limit the corresponding components.

[0077] In the disclosure, expressions such as "A or B", "at least one of A and / or B", "one or more of A and / or B", or the like, can include all possible combinations of the items listed. For example, "A or B", "at least one of A and B", or "at least one of A or B" can refer to all of the following cases: 1) including at least one A; 2) including at least one B; or 3) including both at least one A and at least one B.

[0078] In the disclosure, unless the context clearly indicates otherwise, a singular expression includes a plural expression. It should be further understood that the term "comprise" or "consist of" used in the present application designates the existence of the features, numbers, steps, operations, components, parts, or combinations thereof mentioned in the specification, but does not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0079] When referring to any component (e.g., a first component) being (operatively or communicatively) connected with or to another component (e.g., a second component), it should be understood that any component is directly connected with or to another component, or can be connected with or to another component through other components (e.g., a third component). On the other hand, when referring to any component (e.g., a first component) being "directly connected" or "directly connected to" another component (e.g., a second component), it should be understood that there is no other component (e.g., a third component) between any component and another component.

[0080] The expression "configured (or set) to" used in the disclosure can be replaced with "adapted to", "having the ability of", "designed to", "apt to", "manufactured to", or "capable of", as appropriate. The term "configured (or set) to" does not necessarily mean "designed to" only in hardware. Rather, in any context, the expression "a device configured to" can mean that the device, together with other devices or components, "is capable of". For example, "a processor configured (or set) to perform A, B, and C" can refer to a dedicated processor (e.g., an embedded processor) for performing the corresponding operations, or a general-purpose processor (e.g., a central processing unit (CPU) or an application processor) that can perform the corresponding operations by executing one or more software programs stored in a memory device.

[0081] Embodiments of the disclosure will be described in detail below with reference to the accompanying drawings, so that those skilled in the art to which the disclosure pertains can easily practice the disclosure.

[0082] Figure 1 is a diagram for describing a display module according to an embodiment of the disclosure.

[0083] Referring to Figure 1 , the display module 1 can include a plurality of pixels 100-1, 100-2,..., 100-n (n is a natural number). In this case, the display module 1 can visually display an image (e.g., a photo, a video, etc.) or information (e.g., a letter, a number, a symbol, etc.) through the plurality of pixels 100-1, 100-2,..., 100-n.

[0084] Here, each of the plurality of pixels 100-1, 100-2,..., 100-n can be a minimum unit constituting a screen (area) on which an image or information is displayed on the display module 1, and can be expressed as a point having an independent color or brightness. Meanwhile, since the plurality of pixels 100-1, 100-2,..., 100-n have different positions from each other but have the same structure and function as each other, the description of one pixel 100-1 can be equally applied to the other pixels 100-2,..., 100-n unless otherwise stated. Hereinafter, for convenience of description, the pixel 100-1 will be described.

[0085] The pixel 100-1 can be formed by a combination of a plurality of sub-pixels (e.g., red, green, blue sub-pixels, etc.). That is, one pixel 100-1 can be composed of a combination of colors of a plurality of sub-pixels located in areas adjacent to each other. According to an embodiment, the pixel 100-1 or the sub-pixel can be implemented as a light-emitting semiconductor element (e.g., a light-emitting diode (LED) 50 (see Figure 2 )) Thus, the plurality of pixels 100-1, 100-2,..., 100-n can be implemented as a plurality of semiconductor elements (e.g., a plurality of LEDs 50). More specific details will be described later.

[0086] The plurality of pixels 100-1, 100-2,..., 100-n can be arranged apart from each other with an interval therebetween. According to an embodiment, the interval is predetermined. According to an embodiment, the interval is a regular interval. That is, the plurality of pixels 100-1 and 100-2 can be arranged in a matrix type (e.g., M x N, where M and N are both natural numbers).

[0087] Meanwhile, the display module 1 can be implemented as a display device alone (i.e., a single display module 1), or a plurality of display modules can be combined to be implemented as a single display device. For example, a plurality of display modules can be tiled in a matrix type (e.g., Q x W, where Q and W are both natural numbers) to configure a single display device.

[0088] The display device can refer to a device capable of visually displaying an image by processing an image signal received from an external device or an image signal stored in a storage device through an image processor, or visually displaying information processed by the processor. According to an embodiment, the processor can be a hardware processor. According to an embodiment, the display device can be implemented in various forms such as a television, a monitor, a portable multimedia device, a portable communication device, a smartphone, a smart glass, a smart window, a smart watch, a head-mounted display (HMD), a wearable device, a portable device, a handheld device, a signage, an electronic scoreboard, a bulletin board, a theater screen, a video wall, and the form thereof is not limited.

[0089] That is, the display module 1 according to an embodiment of the disclosure can be installed and applied to a wearable device, a portable device, a handheld device, and an electronic product (i.e., a small display device) or an electronic device requiring various displays in a single unit, and the display module 1 can be arranged by matrix assembly of a plurality of units, applied to an electronic product (i.e., a large display device) or an electronic device such as a monitor, a high-definition television, a signage (or a digital signage), and an electronic scoreboard. In addition, the display module 1 according to an embodiment of the disclosure can also be applied to a transparent display device such as a smart window or a smart glass.

[0090] Hereinafter, the display module 1 according to an embodiment of the disclosure will be described in more detail with reference to the accompanying drawings.

[0091] Figure 2 、 3 , 4A and 4B are diagrams for describing the display module 1 according to an embodiment of the disclosure in more detail. Figure 2 、 3 , 4A and 4B show a cross-sectional view of the display module 1 for one unit LED 50.

[0092] Referring to Figure 2 , the display module 1 according to an embodiment of the disclosure can include a substrate 10, a driving circuit layer 20, an intermediate substrate 40, and an LED 50.

[0093] The substrate 10 can support and protect various electronic elements such as the driving circuit layer 20 and the LED 50. In addition, the substrate 10 can have a transparent property, a rigid property, or a flexible property. According to an embodiment, the substrate 10 can be implemented with various materials such as glass, polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), and polymethyl methacrylate (PMMA).

[0094] The driving circuit layer 20 can be disposed on the substrate 10. The driving circuit layer 20 can be electrically connected to the LED 50, and can cause the LED 50 to emit light by applying power (e.g., voltage or current) to the LED 50. That is, the driving circuit layer 20 can control power to drive the LED 50. Here, the power can be applied in various forms, such as alternating current (AC), direct current (DC), square wave, and triangular wave. Meanwhile, according to a method of controlling driving of the LED 50 (e.g., DC driving, AC driving, pulse width modulation (PWM) driving, etc.), the driving circuit layer 20 can be configured as various circuits.

[0095] As one example, referring to Figure 3 , the driving circuit layer 20 can include a pixel circuit 21 and a plurality of electrodes 28 and 29.

[0096] The pixel circuit 21 can drive the LED 50 such that the LED 50 emits light. According to an embodiment, the LED 50 is mounted (or bonded) on the pixel circuit 21 such that the LED 50 and the pixel circuit 21 can be electrically connected to each other. At this time, the LED 50 can constitute a sub-pixel (e.g., red, green, and blue) of the display module 1. That is, the pixel circuit 21 can be formed for the LED 50 corresponding to one of a red (R) sub-pixel, a green (G) sub-pixel, and a blue (B) sub-pixel.

[0097] According to an embodiment, the pixel circuit 21 can include a switching element, a capacitor, a metal line, an insulator, etc. Here, the switching element can be implemented as an amorphous silicon (A-Si) based TFT, a low temperature polysilicon (LTPS) based TFT, etc. The TFT (or backplane) can include a gate, a source, and a drain, and when a voltage is applied to the gate, a channel is formed, and current flows from the source to the drain, which results in current (or voltage) transmission to the LED 50 such that the LED 50 connected to the pixel circuit 21 emits light. Here, the TFT is not limited to a specific structure or type. That is, the TFT can be implemented as a low temperature polysilicon (LTPS) TFT, an oxide TFT, a polysilicon TFT, an amorphous silicon (a-silicon) TFT, an organic TFT, a graphene TFT, etc., and can be implemented in various types, such as a P-type (or N-type) MOSFET formed in a Si wafer CMOS process.

[0098] The plurality of electrodes 28 and 29 of the driving circuit layer 20 can include a first electrode 28 and a second electrode 29. Here, the first electrode 28 can be one of an anode and a cathode, and the second electrode 29 can be an electrode different from the first electrode 28 among the anode and the cathode. For example, according to an embodiment, the first electrode 28 can be an anode and the second electrode 29 can be a cathode. According to another embodiment, the first electrode 28 can be a cathode and the second electrode 29 can be an anode.

[0099] The plurality of electrodes 28, 29 of the driving circuit layer 20 can be electrically connected to the pixel circuit 21. That is, the first electrode 28 and the second electrode 29 can be electrically connected to the pixel circuit 21 through ohmic contact with the pixel circuit 21. In this case, the pixel circuit 21 can be electrically connected to the LED 50 through the first electrode 28 and the second electrode 29. For example, the pixel circuit 21 can be electrically connected to the first-type semiconductor layer 51 of the LED 50 through the first electrode 28 and the first conductive portions 48 and 58 of the intermediate substrate 40. The pixel circuit 21 can be electrically connected to the second-type semiconductor layer 55 of the LED 50 through the second electrode 29, the second conductive portion 49 of the intermediate substrate 40, and the upper electrode 59 of the LED 50.

[0100] Each of the plurality of electrodes 28 and 29 of the driving circuit layer 20 can be implemented with a material having various properties such as transparency and flexibility properties in addition to having electrical conductivity. For example, each of the plurality of electrodes 28 and 29 can be implemented in a form including at least one of Al, Ti, Ni, Pd, Ag, Au, Au-Ge, indium tin oxide (ITO), or ZnO.

[0101] The intermediate substrate 40 can be attached on the driving circuit layer 20. Also, in this case, the lower portion of the LED 50 can be bonded (or attached) to the upper portion of the intermediate substrate 40, and the upper portion of the driving circuit layer 20 can be bonded (or attached) to the lower portion of the intermediate substrate 40. That is, the intermediate substrate 40 can be attached on the driving circuit layer 20 in a state in which the plurality of LEDs 50 are bonded to the intermediate substrate 40. Accordingly, the driving circuit layer 20 can be electrically connected to the LED 50 through the intermediate substrate 40.

[0102] Here, the intermediate substrate 40 can be a prepreg (pre-impregnated material). At this time, the prepreg can be a general term for a material that is mixed and molded by impregnating a resin with a fiber material (for example, a fiber, a fabric). Since the prepreg can precisely control the ratio of the resin to the fiber material (for example, mainly a carbon fiber material) and can increase the volume ratio of the fiber material, the prepreg has an advantage of improving various properties such as strength, rigidity, corrosion resistance, fatigue life, wear resistance, impact resistance, weight reduction, reliability, and elasticity compared to other materials. Also, when the prepreg is formed in the form of a sheet, it has an advantage that the prepreg can be easily cut in a desired size and used.

[0103] As an example, reference is made to Figure 3The intermediate substrate 40 (e.g., prepreg) can include an adhesive portion 43, first conductive portions 48 and 58, and a second conductive portion 49. The intermediate substrate 40 can be attached to the driving circuit layer 20 by the adhesive portion 43. Specifically, the adhesive portion 43 can be made of a resin or the like, and can have adhesiveness, and the intermediate substrate 40 can be attached to the driving circuit layer 20 by the adhesiveness of the adhesive portion 43.

[0104] Here, the adhesive portion 43 (or adhesive material) can include at least one of an epoxy resin, a polyimide, or a phenol. Accordingly, a surface of the intermediate substrate (e.g., prepreg) 40 can have adhesiveness.

[0105] The driving circuit layer 20 can be electrically connected to the plurality of LEDs 50 by the first conductive portions 48 and 58 and the second conductive portion 49. At this time, the first conductive portions 48 and 58 (or first conductive material) and the second conductive portion 49 (or second conductive material) can be implemented with a fiber material having a predetermined value or more of electrical conductivity. Further, in this case, the plurality of LEDs 50 can be attached to the intermediate substrate 40 by the first conductive portions 48 and 58. Specifically, the plurality of LEDs 50 can be attached to the intermediate substrate 40 by van der Waals force of the first conductive portions 48 and 58. At this time, the van der Waals force is a force acting on a neutral molecule, and the closer the distance between molecules (between molecules of the LEDs 50 and molecules of the first conductive portions 48 and 58), the stronger the strength of the force can be.

[0106] According to an embodiment, each of the first conductive portions 48, 58 and the second conductive portion 49 can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire.

[0107] Here, the CNT can refer to an allotrope of carbon in which carbon atoms have a cylindrical or helical structure. The CNT can have different optical transparency and electrical properties (e.g., electrical conductivity, resistance, etc.) depending on a structure of the CNT (e.g., single-walled CNT (SW-CNT), multi-walled CNT (MW-CNT), etc.), a diameter of the CNT, a molecular length of the CNT, a concentration (or density) of the CNT, and a density of a mixed material (e.g., Ag nanowire, TiOx, etc.). Accordingly, the CNT can be used as a black matrix having high resistance, or can also be used as a transparent electrode having high electrical conductivity.

[0108] The graphene can refer to an allotrope of carbon in which carbon atoms are connected in a hexagonal honeycomb shape to form a two-dimensional planar structure. The graphene can be classified into single-layer graphene or multi-layer graphene depending on the number of layers, and optical transparency and electrical properties can vary depending on the number of layers of the graphene.

[0109] The metal nanowire can refer to a wire structure having a nanometer size. The metal nanowire is in the form of a wire having a diameter of several nanometers to several hundred nanometers, and can include at least one material among Ag, TiOx, Ni, Pt, Au, Si, InP, GaN, or ZnO.

[0110] Meanwhile, the composition or structure of the above intermediate substrate 40 (e.g., prepreg) is merely an example, and various modifications and implementations can be made.

[0111] The LED 50 can be disposed on the intermediate substrate 40. In this case, each of the plurality of LEDs 50 can be electrically connected to the driving circuit layer 20 through the intermediate substrate 40, and can emit light according to power applied from the driving circuit layer 20.

[0112] Here, the LED 50 can refer to a semiconductor light emitting element. For example, the LED 50 can be implemented as a micro-LED element or a mini-LED device based on an inorganic semiconductor. Here, the micro-LED can refer to a semiconductor light emitting element having a width, a length, and a height of 1 to 100 micrometers (μm), and the mini-LED can refer to a semiconductor light emitting element having a width, a length, and a height of 100 to 200 micrometers (μm). However, this is merely an example, and the type thereof is not particularly limited as long as it is a light emitting element in accordance with the purpose of the disclosure.

[0113] As an example, referring to Figure 3 , each of the plurality of LEDs 50 can include a first type semiconductor layer 51, a second type semiconductor layer 55, and a light emitting layer 53.

[0114] The first type semiconductor layer 51 can be one of an n-type semiconductor and a p-type semiconductor, and the second type semiconductor layer 55 can be a semiconductor different from the first type semiconductor layer 51 among the n-type semiconductor and the p-type semiconductor.

[0115] Here, the n-type semiconductor can refer to a semiconductor that transports charges with free electrons as carriers, and the p-type semiconductor can refer to a semiconductor that transports charges with holes as carriers. According to an embodiment, the n-type semiconductor and the p-type semiconductor can be implemented as compound semiconductors, such as Group III-V and Group II-VI. In particular, the n-type semiconductor and the p-type semiconductor can be implemented as nitride semiconductor layers. For example, both the n-type semiconductor and the p-type semiconductor can be n-GaN and p-GaN. However, the n-type semiconductor and the p-type semiconductor according to the disclosure are not limited thereto, and can be made of various materials according to various characteristics required for the display module 1.

[0116] The first-type semiconductor layer 51 and the second-type semiconductor layer 55 can be disposed at the upper and lower portions of the light emitting layer 53, respectively. For example, the first-type semiconductor layer 51 can be disposed at the lower portion of the light emitting layer 53, and the second-type semiconductor layer 55 can be disposed at the upper portion of the light emitting layer 53.

[0117] In the first-type semiconductor layer 51, the intermediate substrate 40 can be bonded to the driving circuit layer 20. That is, when the intermediate substrate 40 is attached to the driving circuit layer 20, the first-type semiconductor layer 51 can be electrically connected to the first electrode 28 of the driving circuit layer 20 through the first conductive portions 48 and 58 of the intermediate substrate 40.

[0118] Specifically, the lower portion of the LED 50, i.e., the first-type semiconductor layer 51, can be in ohmic contact with the first conductive portions 48 and 58 of the intermediate substrate 40. That is, the first-type semiconductor layer 51 can be electrically connected to the driving circuit layer 20 through the first conductive portions 48 and 58 of the intermediate substrate 40. That is, the first conductive portions 48 and 58 of the intermediate substrate 40 can have a function of being electrically connected to the lower electrode of the LED and the driving circuit layer 20.

[0119] After the intermediate substrate 40 is attached to the driving circuit layer 20, the second-type semiconductor layer 55 can be electrically connected to the second electrode 29 of the driving circuit layer 20. The method of electrical connection can differ according to the structure of the LED 50. For example, according to the structure of the LED 50, the method of electrical connection can be a vertical structure, a flip chip structure, etc.

[0120] For example, in the case of the vertical structure, each of the plurality of LEDs 50 can further include an upper electrode 59. At this time, the upper electrode 59 can function as an electrode (or pad) and a wiring.

[0121] Here, after the intermediate substrate 40 is attached to the driving circuit layer 20, the upper electrode 59 can be disposed on the second-type semiconductor layer 55. At this time, the upper electrode 59 can be disposed along the upper portion of the second-type semiconductor layer 55 and the side surface of the LED 50.

[0122] In this case, the second-type semiconductor layer 55 can be electrically connected to the driving circuit layer 20 through the upper electrode 59 of the plurality of LEDs 50. For example, the second-type semiconductor layer 55 can be electrically connected to the second electrode 29 of the driving circuit layer 20 through the upper electrode 59 and the second conductive portion 49 of the intermediate substrate 40. That is, the upper electrode 59 can have a function of electrically connecting between the second-type semiconductor layer 55 of the LED 50 and the second electrode 29 of the driving circuit layer 20.

[0123] The light emitting layer 53 can be disposed between the first-type semiconductor layer 51 and the second-type semiconductor layer 55 through a semiconductor junction.

[0124] Specifically, the light emitting layer 53 can be provided as a single quantum well structure (SQW), a multiple quantum well structure (MQW), or a quantum dot (QD) structure at an interface between an n-type semiconductor and a p-type semiconductor through a junction of the n-type semiconductor and the p-type semiconductor. Here, when the light emitting layer 53 is formed as a multiple quantum well structure, a well / barrier layer of the light emitting layer 53 can be formed in a structure such as InGaN / GaN, InGaN / InGaN, GaAs(InGaAs) / AlGaAs, but the present disclosure is not limited to such a structure. Also, the number of quantum wells included in the light emitting layer 53 is not limited to a specific number.

[0125] In this case, when a current is applied to the first type semiconductor layer 51 and the second type semiconductor layer 55 in a forward bias (for example, connecting a cathode to an n-type semiconductor and connecting an anode to a p-type semiconductor in the case of a p-n junction), the light emitting layer 53 can generate an exciton as electrons of the n-type semiconductor layer and holes of the p-type semiconductor layer recombine in the light emitting layer (for example, a quantum well layer), and can emit light due to a change in the energy state of the exciton. At this time, the wavelength of the emitted light can correspond to the energy band gap of the light emitting layer 53, and the energy band gap can be determined by the structure thereof, such as the composition and film thickness of the semiconductor forming the quantum well (QW) layer.

[0126] Meanwhile, the first type semiconductor layer 51 or the second type semiconductor layer 55 according to the present disclosure can further include various semiconductor layers.

[0127] As an example, the first type semiconductor layer 51 can further include a semiconductor layer (p+ type or n+ type semiconductor layer) doped with a higher doping concentration than a general semiconductor layer (p-type semiconductor layer or n-type semiconductor layer), a semiconductor layer (p- type semiconductor layer or n- type semiconductor layer) doped with a lower doping concentration than a general semiconductor layer (p-type semiconductor layer or n-type semiconductor layer). Also, the first type semiconductor layer 51 can further include an undoped semiconductor layer (for example, u-GaN, etc.). The same description can also apply to the second type semiconductor layer 55.

[0128] Also, as an example, the first type semiconductor layer 51 can further include an electron blocking layer (EBL) or a hole blocking layer (HBL). The electron blocking layer (EBL) can prevent electrons to be moved to the light emitting layer 53 from being lost, and for this purpose, can be formed at a position adjacent to the light emitting layer 53. The hole blocking layer (HBL) can prevent holes to be moved to the light emitting layer 53 from being lost, and can be formed at a position adjacent to the light emitting layer 53. The same description can also apply to the second type semiconductor layer 55.

[0129] According to an embodiment, the LEDs 50 can be LEDs having a vertical structure. For example, each of the plurality of LEDs 50 can have a structure in which one electrode (e.g., a lower electrode) is formed at a bottom and one electrode (e.g., an upper electrode) is formed at a top. That is, as shown in FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14, the LED 50 can be characterized by a structure for forming the upper electrode and the lower electrode. Figure 3 , Figure 4A and Figure 4B According to an embodiment, the display module 1 having the stepless bottom contact structure can maximize the areas of the first-type semiconductor layer 51 and the second-type semiconductor layer 55, and thus the light emitting area of the light emitting layer 53 disposed between the first-type semiconductor layer 51 and the second-type semiconductor layer 55 can be maximized to improve light emitting efficiency.

[0130] In particular, the display module 1 according to an embodiment of the disclosure can have a stepless bottom contact structure unlike a flip chip structure requiring a protrusion (bump or pad (electrode)) between the driving circuit layer 20 and the LED 50 to electrically connect the driving circuit layer 20 and the LED 50. According to an embodiment, in the flip chip structure, two pads can be disposed at the lower portions of the first-type semiconductor layer 51 and the second-type semiconductor layer 55, respectively, and the two pads disposed at the lower portions of the LED 50 and the two electrodes disposed at the upper portions of the driving circuit layer 20 can be electrically connected to each other by a bump located therebetween. The flip chip structure is a structure in which the area of the first-type semiconductor layer 51 is smaller than the area of the second-type semiconductor layer 55 with reference to a horizontal plane, and the area of the light emitting layer 53 disposed on the interface between the first-type semiconductor layer 51 and the second-type semiconductor layer 55 is also smaller than the area of the second-type semiconductor layer 55.

[0131] According to an embodiment, the display module 1 having the stepless bottom contact structure does not need to form a protrusion such as a pad and a bump by disposing a step on the lower surfaces of the first-type semiconductor layer 51 and the second-type semiconductor layer 55 of the LED 50, because the display module 1 having the stepless bottom contact structure can electrically connect the driving circuit layer 20 and the LED 50 through the intermediate substrate 40. That is, the intermediate substrate 40 can replace the protrusion such as a pad and a bump.

[0132] Accordingly, the display module 1 having the stepless bottom contact structure can maximize the areas of the first-type semiconductor layer 51 and the second-type semiconductor layer 55, and thus the light emitting area of the light emitting layer 53 disposed between the first-type semiconductor layer 51 and the second-type semiconductor layer 55 can be maximized to improve light emitting efficiency.

[0133] Further, the display module 1 having the stepless bottom contact structure can prevent the risk of short circuiting of the two electrodes, because the two electrodes (or pads) of the LED 50 are formed at different positions (e.g., the upper and lower portions of the LED 50). In particular, when the LED 50 is miniaturized, the stepless bottom contact structure in which the two electrodes are located at the upper and lower portions of the LED 50 can effectively prevent the risk of short circuiting, as compared to the flip chip structure in which the two electrodes are located at the lower portion of the LED 50.

[0134] In addition, the LED 50 applied to the display module 1 according to the disclosure is a package form between a related art surface mount device (SMD) and a chip size package (CSP), and can maintain the advantages of size and cost, respectively, while solving the Mura problem caused by light leakage in the related art light emitting element. In addition, the structure of the display module 1 according to the disclosure can improve the light emitting efficiency and the yield in the manufacturing process.

[0135] Meanwhile, referring to Figure 3 , the display module 1 according to the embodiment of the disclosure can further include a passivation element 57.

[0136] The passivation element 57 can be disposed on the sidewall of the LED 50. For example, the passivation element 57 can be disposed on the sidewall of the first type semiconductor layer 51, the light emitting layer 53, and the second type semiconductor layer 55. Meanwhile, the upper electrode 59 can be formed along the passivation element 57.

[0137] In this case, the passivation element 57 can perform a function for improving the light emitting efficiency of the light emitting layer 53 and protecting the semiconductor layer and the light emitting layer 53 from external (e.g., insulating layer and impurities). According to the embodiment, the passivation element 57 can be implemented with various insulating materials such as Al2O3, SiN, and SiO2. However, this is only an example, and the material of the passivation element 57 is not limited to a specific material.

[0138] Meanwhile, according to the embodiment of the disclosure, referring to Figure 3 、 4A and 4B, the light emitting direction of the LED 50 can be one of a top side, a bottom side, and both sides. Here, the top side, the bottom side, and the both sides can refer to a direction in which light travels to the outside of the LED 50, as indicated by the arrow directions shown in Figure 3 、 4A , 4B. The light emitting direction can be determined according to the position of the reflective electrode 56 (see Figure 4A and 4B ) and the penetrability (or transparency) of the material disposed on the upper and lower parts of the LED 50.

[0139] Referring to Figure 3 , the light emitting direction of the LED 50 according to the embodiment of the disclosure can be both sides (or double side light emission). In this case, no reflective layer is inserted (included) inside the LED 50, and the light emitted from the light emitting layer 53 of the LED 50 can travel in the top side and the bottom side of the display module 1. Here, when the light emitting direction is both sides, an image can be displayed on the front surface (top side) and the rear surface (bottom side) of the display module 1.

[0140] In this case, the upper electrode 59, the first and second conductive portions 48, 58, the drive circuit layer 20 (including the first and second electrodes 28, 29 of the drive circuit layer 20), and the substrate 10 can each be made of a material (a penetrable material) that is conducive to penetration, i.e., a material that has high penetrability and does not absorb light emitted (e.g., glass, ITO, a metal nanofilm, graphene, etc.).

[0141] Here, the upper electrode 59 included in the LED 50 can be implemented as a transparent electrode. Thus, light traveling in the top direction is not blocked by the transparent electrode and can be transmitted through the transparent electrode. At this time, the transparent electrode can refer to an electrode that has excellent electrical properties while transmitting light through high light transmittance. For example, the transparent electrode can refer to an electrode that has a transmittance of 80% or more in the visible light region including blue, green, and red (e.g., light having a wavelength in the range of 450 nm to 680 nm) in terms of optical properties, and has a low sheet resistance (Ω / sq) of several hundreds or less and a high electrical conductivity (S / m) of several hundreds or more in terms of electrical properties.

[0142] Here, the transparent electrode can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire, and can be implemented with various materials having high light transmittance and electrical conductivity, such as indium tin oxide (ITO), a conductive polymer (e.g., Pedot:pss, etc.), Au, Pt, SnO2, and TiO2. In addition, the transparent electrode can be implemented with a film material having flexibility.

[0143] The transparent electrode can include a CNT formed to have high electrical conductivity and transparent properties, according to the structure of the CNT (e.g., a single-walled CNT (SW-CNT), a multi-walled CNT (MW-CNT), etc.), the diameter of the CNT, the molecular length of the CNT, the concentration (or density) of the CNT, and the density of a mixed material (e.g., an Ag nanowire, etc.).

[0144] Here, the first and second conductive portions 48, 58 and the second conductive portion 49 can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire having transparent properties.

[0145] In this case, the transparent electrode can be formed of the same material as the first and second conductive portions 48, 58 and the second conductive portion 49 of the intermediate substrate 40.

[0146] Referring to Figure 4A and Figure 4B The LED 50 according to an embodiment of the disclosure can further include a reflective electrode 56. In this case, the reflective electrode 56 serves to adjust the traveling direction of light emitted from the LED 50.

[0147] As an example, referring to Figure 4AIn this case, the light emitted from the light emitting layer 53 of the LED 50 can travel in the top side of the display module 1.

[0148] Here, the reflective electrode 56 can be disposed at the lower portion of the first type semiconductor layer 51, as shown in Figure 4A In this case, the first type semiconductor layer 51 can be electrically connected to the driving circuit layer 20 through the reflective electrode 56 and the first conductive portions 48 and 58 of the intermediate substrate 40. The method of forming the reflective electrode 56 will be described later in the process of Figure 6B

[0149] Specifically, the reflective electrode 56 can reflect light in a direction different from the traveling direction of light emitted from the light emitting layer 53 and incident on the reflective electrode 56. For example, when the reflective electrode 56 is disposed at the lower portion of the first type semiconductor layer 51, the reflective electrode 56 can reflect light from the upper surface of the reflective electrode 56 when light emitted from the bottom side of the light emitting layer 53 reaches the reflective electrode 56. At this time, the direction of the reflected light can be the top side of the light emitting layer 53.

[0150] According to an embodiment, the reflective electrode 56 can be disposed in the structure of a metal reflector or a distributed Bragg reflector (DBR). In addition, the reflective electrode 56 can be made of a material such as aluminum (Al) or the like.

[0151] For example, the distributed Bragg reflector structure can be implemented as a multilayer structure in which two layers having different refractive indices are alternately stacked. Thus, due to the difference in the refractive indices of the two layers, Fresnel reflection occurs at the interface of each layer, and depending on the materials included in the multilayer structure and the thickness thereof, all reflected waves can cause constructive interference.

[0152] In this case, in order not to block light traveling in the top side, the upper electrode 59 can be implemented as a material having high transmittance and not absorbing light emitted. That is, the upper electrode 59 can be implemented as a transparent electrode, which has been described before and will not be repeated here. Meanwhile, the first conductive portions 58, 48 and the second conductive portions 49, the driving circuit layer 20 (including the first electrode 28 and the second electrode 29 of the driving circuit layer 20), and the substrate 10 each can be implemented as a non-transmittable material regardless of the traveling path of light, but this is only an example and can also be implemented as a transmittable material.

[0153] As another example, referring to Figure 4B , the light emitting direction of the LED 50 can be the bottom side (or rear light emission). In this case, a reflective layer is inserted (included) inside the LED 50, and light emitted from the light emitting layer 53 of the LED 50 can travel in the bottom side of the display module 1. ​

[0154] Here, the reflective electrode 56 can be disposed on an upper portion of the second-type semiconductor layer 55, as shown. Figure 4B In this case, the second-type semiconductor layer 55 can be electrically connected to the second electrode 29 of the driving circuit layer 20 through the reflective electrode 56, the upper electrode 59, and the conductive material 49 of the intermediate substrate 40.

[0155] For example, when the reflective electrode 56 is disposed on the upper portion of the second-type semiconductor layer 55, the reflective electrode 56 can reflect light from the lower surface of the reflective electrode 56 when the light emitted from the top side of the light emitting layer 53 reaches the reflective electrode 56. At this time, the direction of the reflected light can be the bottom side of the light emitting layer 53.

[0156] In this case, the first conductive portion 48, 58 and the second conductive portion 49, the driving circuit layer 20 (including the first electrode 28 and the second electrode 29 of the driving circuit layer 20), and the substrate 10 can each be made of a material (a penetrable material) that is helpful for penetration, i.e., a material having high penetration and not absorbing light emitted (for example, glass, ITO, a metal nanofilm, graphene, etc.). On the other hand, the upper electrode 59 can be implemented as a non-penetrable material since it is irrelevant to the travel path of light, but this is only an example and can also be implemented as a penetrable material.

[0157] Meanwhile, referring to Figure 4A and 4B , the display module 1 can further include a black matrix 60.

[0158] The black matrix 60 can be disposed in an area between the plurality of LEDs 50 on the intermediate substrate 40. That is, the black matrix 60 can be disposed in an area between the LED 50-1 and another LED 50-2 on the intermediate substrate 40.

[0159] The black matrix 60 can include a material that absorbs light and appears black. In addition, the black matrix 60 can include a material having high resistance properties (or insulating properties). According to an embodiment, the black matrix 60 can include various materials such as CNT, a polymer, and a metal oxide.

[0160] In particular, the black matrix 60 can include CNT formed to have low conductivity and light absorption properties according to the structure of the CNT (for example, single-walled CNT (SW-CNT), multi-walled CNT (MW-CNT), etc.), the diameter of the CNT, the molecular length of the CNT, the concentration (or density) of the CNT, and the density of a mixed material (for example, Ag nanowire, etc.).

[0161] According to the embodiments of the disclosure as described above, there are advantages of reducing costs and improving reliability by simplifying the process and solving the problem of yield reduction, because in order to connect the LED and the driving circuit layer, an electrode (for example, a lower electrode) is provided at the lower portion of the LED, and there is no need to perform a process requiring heat treatment, such as anisotropic conductive film (ACF) or bump welding.

[0162] In addition, the display module 1 according to the disclosure is a stepless bottom combined μ-LED structure, which has the advantage of being a stepless structure without the need to separately provide pads / bumps at the lower portion of the LED for connection, the driving circuit layer 20 is directly combined with the LED 50, and there is no need for ACF with a molding function.

[0163] In addition, there is also an advantage in that the middle substrate 40 at the lower portion of the LED 50 can be used as an ohmic contact and a bonding agent at the same time. Due to these advantages, the contact area between the circuit board and the LED element can be expanded, and thus the heat dissipation effect can be improved.

[0164] In addition, in the display module 1 according to the disclosure, the LED 50 can be easily transferred (or attached) to the driving circuit layer 20 using the middle substrate 40.

[0165] Here, when the middle substrate 40 to which the LED 50 is attached is attached to the driving circuit layer 20 (or the TFT layer), one or more LEDs 50 can be attached. At this time, LEDs 50 of the same color (or the same sub-pixel) can be simultaneously transferred in a bar unit (for example, a column unit or a row unit) or other aggregation units. In addition, when LEDs 50 of R, G, and B sub-pixels are arranged and attached on the middle substrate 40, a unit pixel or a plurality of pixels can be simultaneously transferred to the driving circuit layer 20.

[0166] Therefore, the display module 1 according to the disclosure and the manufacturing method thereof can improve the overall production yield while improving the transfer speed of the LED 50.

[0167] Figure 5 is a flowchart for describing a method of manufacturing a display module according to an embodiment of the disclosure.

[0168] Referring to Figure 5 , the manufacturing method of the display module 1 can include an operation of forming an epitaxial film including a light emitting layer, a first type semiconductor layer, and a second type semiconductor layer (S510), an operation of attaching the epitaxial film to a middle substrate 40 including a conductive material (S520), an operation of patterning the attached epitaxial film to form a light emitting diode (LED) 50 (S530), and an operation of electrically connecting the LED 50 to a driving circuit layer 20 through the conductive material (S540).

[0169] The various operations of the method for manufacturing a display module according to the present disclosure will now be described with reference to the accompanying drawings.

[0170] Figure 6A and 6B are diagrams for describing an operation of forming an epitaxial film according to an embodiment of the present disclosure.

[0171] According to an embodiment, in operation (S510), an epitaxial film 700 can be formed on the growth substrate 600. According to an embodiment, the epitaxial film 700 can include the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650. Accordingly, the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650 can be formed on the growth substrate 600 (S510).

[0172] Here, the growth substrate 600 can be a material or a wafer suitable for semiconductor growth (epitaxy). For example, the growth substrate 600 can be implemented with a material such as silicon (Si), sapphire (Al2SO4), SiC, GaN, GaAs, or ZnO. On the other hand, the growth substrate 600 can be used as a substrate for epitaxially growing the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650, and then separated therefrom and removed.

[0173] When the growth substrate 600 is provided, the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650 can be sequentially formed on the growth substrate 600. According to an example embodiment, when the growth substrate 600 is provided, the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650 can be sequentially grown on the growth substrate 600. At this time, Figure 3 The description of the first-type semiconductor layer 51, the light-emitting layer 53, and the second-type semiconductor layer 55 described above can be equally applied to each of the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650, and thus will not be described again.

[0174] According to an embodiment, the growth of the semiconductor layer can be implemented using process technologies such as metal organic vapor phase epitaxy (MOVPE), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), liquid phase epitaxy (LPE), and vapor phase epitaxy (VPE).

[0175] Here, the epitaxial film 700 can include the first-type semiconductor layer 610, the light-emitting layer 630, and the second-type semiconductor layer 650, and can refer to a film implemented in the form of a thin film having a thickness (height in the vertical direction) of several nanometers to several tens of micrometers.

[0176] Furthermore, the dimensions of the epitaxial film 700 (area on a plane with height as the normal or diagonal length) can correspond to the dimensions of the growth substrate 600. For example, the dimensions of the epitaxial film 700 can be substantially the same as or smaller than the dimensions of the growth substrate 600 (e.g., a 10-inch wafer).

[0177] Furthermore, the first type semiconductor layer 610, the light-emitting layer 630, and the second type semiconductor layer 650 may each include semiconductor layers with various properties, such as hole blocking layers or electron blocking layers, without limiting the technical spirit of this disclosure.

[0178] Meanwhile, the light emission direction of the display module 1 manufactured according to the manufacturing method of this disclosure can be one of the top side, the bottom side, or both the top side and the bottom side.

[0179] The manufacturing method according to embodiments of this disclosure may not require the formation of reflective electrodes. In this case, the light emission direction of the display module 1 manufactured by the following operations can be either the top side or the bottom side.

[0180] According to another embodiment, the manufacturing method may include forming a reflective electrode. In this case, depending on the position of the electrode, the light emission direction of the display module 1 manufactured by the following operations may be either the top side or the bottom side.

[0181] For example, according to Figure 6B In the illustrated embodiment, a first type semiconductor layer 610, a light-emitting layer 630, and a second type semiconductor layer 650 can be sequentially formed (grown) on a growth substrate 600, and then a reflective electrode 660 can be formed on the second type semiconductor layer 650. That is, when in... Figure 6A When the reflective electrode 660 is formed in the state of [condition], [the following can be obtained] Figure 6B In this case, the light emission direction of the display module 1 manufactured by the following operations can be the top side.

[0182] At this point, the reflective electrode 660 can be formed on the second type semiconductor layer 650 using processes such as atomic layer deposition (ALD), electron beam evaporation, and sputtering. The reflective electrode 660 can be formed to have a thickness (vertical height) of several nanometers to tens of micrometers.

[0183] Here, the reflective electrode 660 can be configured as a layer comprising a metallic material (e.g., Al, Ag-Pd-Cu alloy, etc.). Furthermore, the reflective electrode 660 can be configured as a single layer or multiple layers. For example, the reflective electrode 660 can be configured as a multi-layer structure with a cyclic layer structure, including a first reflective layer formed of aluminum, a second reflective layer formed on the first reflective layer and formed of aluminum nitride, and a third reflective layer formed on the second reflective layer and formed of aluminum.

[0184] Meanwhile, various metallic materials having high reflectivity can be used for the reflective electrode 660 described above, but the material of the reflective electrode 660 is not limited to a specific material and can be implemented by modification with various materials.

[0185] According to another example embodiment, the reflective electrode 660 can be formed on the substrate 600, and then the first-type semiconductor layer 610, the light emitting layer 630, and the second-type semiconductor layer 650 can be sequentially formed on the reflective electrode 660.

[0186] Figure 7A and Figure 7B is a cross-sectional view for describing an operation of separating an epitaxial film according to an embodiment of the disclosure.

[0187] Referring to Figure 7A and Figure 7B , the epitaxial film 700 can be separated from the growth substrate 600. Here, the epitaxial film 700 can include the first-type semiconductor layer 610, the light emitting layer 630, and the second-type semiconductor layer 650. According to an embodiment, the separation (removal) of the growth substrate 600 can be performed by various methods, such as laser lift-off (LLO), lift-off, wet etching, etc.

[0188] As an example, referring to Figure 7A , the first-type semiconductor layer 610, the light emitting layer 630, and the second-type semiconductor layer 650 can be sequentially formed on the growth substrate 600, and the epitaxial film 700 including the first-type semiconductor layer 610, the light emitting layer 630, and the second-type semiconductor layer 650 can be separated from the growth substrate 600. That is, the epitaxial film 700 can be separated in a state as shown in Figure 6A In this case, when the reflective electrode is formed before a subsequent patterning operation, the light emitting direction can be changed to the bottom side, and when the reflective electrode is not formed, the light emitting direction can be changed to both sides.

[0189] As another example, referring to Figure 7B , the first-type semiconductor layer 610, the light emitting layer 630, the second-type semiconductor layer 650, and the reflective electrode 660 can be sequentially formed on the growth substrate 600, and the epitaxial film 700 including the first-type semiconductor layer 610, the light emitting layer 630, the second-type semiconductor layer 650, and the reflective electrode 660 can be separated from the growth substrate 600. That is, the epitaxial film 700 can be separated in a state as shown in Figure 6B In this case, the light emitting direction can be changed to the top side.

[0190] Figure 8A to 8C is a view for describing an operation of forming an intermediate substrate according to an embodiment of the disclosure. Hereinafter, a method of manufacturing the intermediate substrate 800 will be described first, and then step S520 will be described.

[0191] Referring to Figure 8A , the intermediate substrate 800 can be formed by impregnating the conductive material 810 with the adhesive material 820. That is, the intermediate substrate 800 can include the conductive material 810 and the adhesive material 820, and can be implemented as, for example, a prepreg including the conductive material 810 and the adhesive material 820. Here, the descriptions of the intermediate substrate 40, the conductive materials 48, 49, and 58, and the adhesive material 43 can be equally applied to each of the intermediate substrate 800, the conductive material 810, and the adhesive material 820, and thus will not be repeated.

[0192] Referring to Figure 8A and 8B , one or more regions 825 of the adhesive material 820 of the intermediate substrate 800 can be removed. Here, the adhesive material 820 formed in the one or more regions 825 is removed in order to form the conductive material in the removed portions. The positions (or intervals) of the one or more regions 825 can correspond to the positions (or intervals) of the electrodes of the driving circuit layer 20, such that the conductive material and the electrodes of the driving circuit layer 20 are electrically connected to each other.

[0193] At this time, in order to remove the one or more regions 825 of the adhesive material 820, a photolithography and etching process can be used.

[0194] For example, the exposed regions (or unexposed regions) can be removed by forming a photoresist on the adhesive material 820, and then exposing and developing only a specific region of the photoresist formed on the adhesive material 820 through a mask in which an opening (or a light-transmissive portion) is formed, depending on the type of the photoresist (e.g., positive PR or negative PR).

[0195] In this case, as shown in Figure 8A , in order to remove the adhesive material 820 formed in the one or more regions 825, as shown in Figure 8B , a gray-tone process (e.g., O2 gas, plasma surface treatment, organic film removal, etc.) can be performed on the one or more regions 845 in which the photoresist 840 is not left.

[0196] Further, referring to Figure 8B and 8C , the conductive material 850 can be formed in the one or more regions 845 in which the adhesive material 820 is removed, in a state in which the photoresist 840 is formed on the adhesive material 830. At this time, the remaining photoresist 840 serves to prevent the conductive material from being formed on the adhesive material 830. Meanwhile, as a method of forming the conductive material 850, spraying, MOCVD, MOVPE, MBE deposition, etc. can be used.

[0197] Thereafter, by removing the remaining photoresist 840, the intermediate substrate 800 can include a prepreg including the conductive materials 810 and 850 and the adhesive material 830, as shown in Figure 8C

[0198] Meanwhile, the conductive materials 810 and 850 can include at least one of carbon nanotubes (CNTs), graphene, or metal nanowires, and the adhesive material 830 can include at least one of epoxy, polyimide, or phenol.

[0199] On the other hand, the above-described operation of forming the intermediate substrate 800 is described as being performed after the operation (S510) of forming the epitaxial film 700, but can also be performed before the operation (S510) of forming the epitaxial film 700 or concurrently in parallel with the operation (S510) of forming the epitaxial film 700.

[0200] Figure 9A to 9D is a diagram for describing an operation of bonding the epitaxial film to the intermediate substrate according to an embodiment of the disclosure.

[0201] Referring to Figure 9A and Figure 9B , the epitaxial film 700 can be attached (bonded) to the intermediate substrate 800. At this time, the epitaxial film 700 can be directly bonded to the intermediate substrate 800 without other media (e.g., solder bumps, ACF, etc.).

[0202] Specifically, the epitaxial film 700 separated from the growth substrate 600 can be attached (or bonded) to the intermediate substrate 800. For example, one surface (e.g., the upper surface of the second-type semiconductor layer 650 or the upper surface of the reflective electrode 660) of the epitaxial film 700 opposite to the surface (e.g., the lower surface of the first-type semiconductor layer 610) separated from the growth substrate 600 can be attached (bonded) to the intermediate substrate 800. That is, the top and bottom of the epitaxial film 700 can be changed to be directly bonded to the intermediate substrate 800.

[0203] Here, in the intermediate substrate 800, the conductive material 810 can be located at the upper portion thereof, and the adhesive material 830 can be located at the lower portion thereof. That is, the epitaxial film 700 can be attached to the intermediate substrate 800 such that the second-type semiconductor layer 650 of the epitaxial film 700 abuts (faces) the conductive material 810 of the intermediate substrate 800.

[0204] At this time, the epitaxial film 700 can be attached to the intermediate substrate 800 by van der Waals force of the conductive material 810.

[0205] ​According to embodiments, the epitaxial film 700 can be attached to the intermediate substrate 800 by various methods such as roll-to-roll, roll forming, vacuum pressing, and pressing in which the plate moves vertically and is pressed. For example, in the case of roll forming, the epitaxial film 700 and the intermediate substrate 800 can be arranged in the same direction. In this case, when the roller presses the epitaxial film 700 while rotating, the epitaxial film 700 can be attached to the roller while being rolled. When the roller presses the intermediate substrate 800 while rotating again, the epitaxial film 700 attached to the roller can be transferred and attached to the intermediate substrate 800.

[0206] Reference Figure 7A and Figure 9A The epitaxial film 700 can be attached (or bonded) to the intermediate substrate 800 such that, in the absence of a reflective electrode, the first type semiconductor layer 610 of the epitaxial film 700 is located on its upper portion, and the second type semiconductor layer 650, opposite to the position of the first type semiconductor layer 610 of the epitaxial film 700, is located on its lower portion. That is, the epitaxial film 700 can be attached (or bonded) to the intermediate substrate 800 such that one surface of the second type semiconductor layer 650 of the epitaxial film 700 contacts the upper portion of the intermediate substrate 800.

[0207] Here, as an example, when in Figure 9A When a patterning operation is performed without forming a reflective electrode in the desired state (S530), the light emission direction can be changed to both sides. As another example, when in... Figure 9A In such a state Figure 9C When performing a patterning operation (S530) after forming the reflective electrode, the light emission direction can be changed to the bottom side.

[0208] Specifically, refer to Figure 9C After the epitaxial film 700, including the first type semiconductor layer 610, the light-emitting layer 630, and the second type semiconductor layer 650, is attached (or bonded) to the intermediate substrate 800, a reflective electrode 660' can be formed on the upper part of the first type semiconductor layer 610. At this time, the reflective electrode 660' can be formed on the first type semiconductor layer 610 by processes such as atomic layer deposition (ALD), electron beam evaporation, and sputtering. The description of the reflective electrode 660 is equally applicable to the reflective electrode 660', and therefore will not be repeated. In this case, because the reflective electrode 660' is formed on the upper part of the epitaxial film 700, the light-emitting direction can be changed to the bottom side.

[0209] On the other hand, as another example, see Figure 7B and Figure 9B, the first type semiconductor layer 610 of the epitaxial film 700 can be attached (or bonded) to the intermediate substrate 800 so that the first type semiconductor layer 610 of the epitaxial film 700 is located at an upper portion thereof in a state in which the reflective electrode is formed, and the reflective electrode 660 opposite to the position of the first type semiconductor layer 610 of the epitaxial film 700 is located at a lower portion thereof. That is, the epitaxial film 700 can be attached (or bonded) to the intermediate substrate 800 so that one surface of the reflective electrode 660 of the epitaxial film 700 contacts an upper portion of the intermediate substrate 800. In this case, since the reflective electrode 660 is formed at a lower portion of the epitaxial film 700, the light emission direction can be changed to the top side.

[0210] Figure 10A to 10F is a diagram for describing an operation of patterning the epitaxial film in accordance with an embodiment of the disclosure. Here, Figure 10A to 10C is a diagram for describing an operation of patterning the epitaxial film 700 in a state in which the reflective electrode is not formed as Figure 9A is shown, and Figure 10D and 10E is a diagram for describing an operation of patterning the epitaxial film 700 in a state in which the reflective electrode 660 and 660', respectively, are formed as Figure 9B and 9C is shown. Figure 10A and 10B is a diagram of a structure of the LED 50 obtained by patterning the epitaxial film 700 as

[0211] Referring to Figure 10A to 10F , the epitaxial film 700 attached to the intermediate substrate 800 can be patterned to form a light emitting diode (LED) 50 (S530). At this time, the LED 50 formed due to the patterning can include a light emitting layer 53, and a first type semiconductor layer 51 and a second type semiconductor layer 55 formed at upper and lower portions of the light emitting layer 53, respectively. Here, the LED 50 can refer to one of a plurality of LEDs 50-1 and 50-2 as Figure 10C-10E is shown.

[0212] Specifically, referring to Figure 10A and 10B , the epitaxial film 700 bonded to the intermediate substrate 800 can be patterned. At this time, a photolithography process and an etching process can be used.

[0213] For example, after the photoresist 1010 is formed on the first type semiconductor layer 610, a mask 1020 having an opening (or a light-transmissive portion) formed thereon can be aligned on the photoresist 1010, and a specific region 1011 of the photoresist 1010 can be exposed through the opening of the mask 1020.

[0214] In this case, the epitaxial film 700 can be patterned as Figure 10BThe photoresist 1010 is developed to remove the exposed regions (or unexposed regions), and an etching process can be performed on one or more regions 1030 in which the photoresist 1013 is not left. As a result, one or more regions 1030 can be removed. At this time, as the etching process, a wet etching, a dry etching, a plasma, a physical etching, a chemical etching, or the like can be used. Here, the one or more regions 1030 can be a grid-shaped region, and can include the conductive material 49 and can be a region not including the conductive material 48.

[0215] Thereafter, by removing the remaining photoresist 1013, as Figure 10C-10F illustrated, the epitaxial film 700 can be formed in a form in which the plurality of LEDs 50-1 and 50-2 are separated from each other. In this case, the first-type semiconductor layer 51 of the LEDs 50-1 and 50-2 can be formed based on the second-type semiconductor layer 650 of the epitaxial film 700, the light emitting layer 53 of the LEDs 50-1 and 50-2 can be formed based on the light emitting layer 630 of the epitaxial film 700, and the plurality of second-type semiconductor layers 55 of the LEDs 50-1 and 50-2 can be formed based on the first-type semiconductor layer 610 of the epitaxial film 700.

[0216] That is, as Figure 10A and 10B illustrated, the epitaxial film 700 attached (or bonded) to the intermediate substrate 800 can be patterned to form a plurality of LEDs 50-1 and 50-2 on the intermediate substrate 40 as Figure 10C and 10F illustrated.

[0217] Further, a part of the conductive material 810 formed on the intermediate substrate 40 can be removed, and a remaining part of the conductive material 810 can be left. Here, as Figure 10C illustrated, the part left in the intermediate substrate 40 will be referred to as the conductive materials 58 and 48. Further, the adhesive material 43 can be left in the intermediate substrate 40. That is, the intermediate substrate 40 on which the patterning operation has been performed can include the conductive materials 48 and 58 and the adhesive material 43.

[0218] On the other hand, in the display module 1, the pitch, that is, the interval between the LEDs 50-1 and 50-2, can be designed (predetermined) according to the resolution, the size, the number of pixels, or the like. Accordingly, the electrodes (for example, the first electrodes 28 or the like) of the driving circuit layer 20 in combination with the LEDs 50-1 and 50-2 can be disposed (formed) to be spaced apart from each other at an interval (for example, an interval within an error range) corresponding to the predetermined pitch.

[0219] Here, because the intermediate substrate 40 applied to the display module 1 is implemented in a material having elasticity or stretchability, when a physical force is applied to the intermediate substrate 40, the intermediate substrate 40 can be stretched in the direction of the applied force. Accordingly, the interval between the conductive materials 48 of the intermediate substrate 40 (or the interval between the LEDs 50-1 and 50-2) can also increase.

[0220] In the manufacturing method according to the embodiment of the disclosure, by using the elasticity or stretchability of the intermediate substrate 40, the LEDs 50-1 and 50-2 having an interval smaller than a predetermined pitch can be formed based on the epitaxial film 700 attached to the intermediate substrate 40, and a physical force (e.g., tension) in the horizontal direction can be applied to the intermediate substrate 40 so that the interval between the LEDs 50-1 and 50-2 is the predetermined pitch.

[0221] Specifically, the conductive materials 48 of the intermediate substrate 40 can be formed to be spaced apart from each other at an interval (e.g., 40 µm) smaller than a predetermined pitch (e.g., 50 µm). In this case, after the epitaxial film 700 is attached to the intermediate substrate 800, one region 1030 of the intermediate substrate 800 and the epitaxial film 700 can be removed through a patterning operation to form the LEDs 50-1 and 50-2 that are separated from each other (individual). Here, the interval between the LEDs 50-1 and 50-2 can be an interval (e.g., 40 µm) smaller than the predetermined pitch (e.g., 50 µm), and can be a value identical to the horizontal length of the one region 1030 removed from the epitaxial film 700. Thereafter, a physical force (e.g., tension) in the horizontal direction can be applied to the intermediate substrate 40 so that the interval between the LEDs 50-1 and 50-2 is an interval (e.g., 50 µm, including an error range) substantially identical to the predetermined pitch.

[0222] According to the embodiment of the disclosure as described above, the size (area) of the one region 1030 removed from the epitaxial film 700 can be small, and thus, a portion (area) discarded from the epitaxial film 700 grown through the growth substrate 600 (e.g., wafer) having a limited size can be reduced, thereby improving resource efficiency, and the integration of the LEDs 50-1 and 50-2 formed based on the epitaxial film 700 can be increased.

[0223] Furthermore, according to embodiments of this disclosure, since the spacing between the conductive materials 48 and between LEDs 50-1 and 50-2 can be freely adjusted using the elasticity or stretchability of the intermediate substrate 40, process errors such as errors in the electrode spacing of the driving circuit layer can be resolved, and display devices of various sizes or with various pitches can be manufactured without establishing separate production lines for each size. For example, depending on the tension applied to the same 9.5-inch display module, display devices of various sizes, such as 10-inch and 11-inch display devices, can be manufactured.

[0224] On the other hand, when in such Figure 9A When patterning the epitaxial film 700 is performed in the state where no reflective electrode is formed, as shown, it can be done as follows: Figure 10C The diagram shows LEDs 50-1 and 50-2 without reflective electrodes. In this case, since neither LED 50-1 nor 50-2 includes a reflective electrode, the light emission direction can be changed to both sides.

[0225] On the other hand, when in such Figure 9B The reflective electrode 660 shown is formed on the lower part of the epitaxial film 700, and the epitaxial film 700 is subjected to the following process: Figure 10A and 10B During the patterning operation shown, it can be done as follows: Figure 10D The LEDs 50-1 and 50-2 are shown with the reflective electrode 56 located below them. In this case, since both LEDs 50-1 and 50-2 include the reflective electrode 56 formed below them, the light emission direction can be changed to the top side.

[0226] On the other hand, when in such Figure 9C The reflective electrode 660' shown is formed on the upper part of the epitaxial film 700, and the epitaxial film 700 is subjected to the following process: Figure 10A and 10B During the patterning operation shown, it can be done as follows: Figure 10E The LEDs 50-1 and 50-2 are shown with reflective electrodes 56' located on their upper parts. In this case, since both LEDs 50-1 and 50-2 include reflective electrodes 56' formed on their upper parts, the light emission direction can be changed to the bottom side.

[0227] Figure 11A to 11C This is a diagram illustrating a method for forming passivation according to embodiments of the present disclosure.

[0228] Reference Figure 11A to 11CThe manufacturing method according to the embodiment of the disclosure can further include an operation of forming the passivation element 57 on the sidewall of the LEDs 50-1 and 50-2. According to the embodiment, the passivation element 57 can be formed by a deposition method such as atomic layer deposition, electron beam deposition, sputtering, etc. The passivation 57 can include an insulating material, which has been described before, and will not be repeated here.

[0229] As an example, as shown in FIGS. 1A and 1B, in a case where the reflective electrodes 56 and 56' are not formed in the LEDs 50-1 and 50-2, the passivation element 57 can be formed on the sidewall of the LEDs 50-1 and 50-2. Specifically, the passivation element 57 can be formed to surround the sidewall (or side surface) of each of the first-type semiconductor layer 51, the light-emitting layer 53, the second-type semiconductor layer 55, and the conductive material 58 of the LED 50. Figure 11A

[0230] As another example, as shown in FIGS. 2A and 2B, in a case where the reflective electrodes 56 and 56' are formed in the LEDs 50-1 and 50-2, the passivation element 57 can be formed on the sidewall of the LEDs 50-1 and 50-2. Specifically, the passivation element 57 can be formed to surround the sidewall (or side surface) of each of the first-type semiconductor layer 51, the light-emitting layer 53, the second-type semiconductor layer 55, the conductive material 58, and the reflective electrodes 56 and 56' of the LED 50. Figure 11B 11C

[0231] Therefore, since the passivation element 57 includes an insulating material, the light-emitting efficiency of the light-emitting layer 53 can be improved, and the semiconductor layer and the light-emitting layer 53 can be protected from the outside (e.g., an insulating layer and impurities).

[0232] Figure 12A 12B FIGS. 3A and 3B are diagrams for describing a checking method according to an embodiment of the disclosure. Figure 12A 12B FIGS. 3A and 3B show the LEDs 50-1 and 50-2 in a state where the reflective electrodes are not formed, but this is only for ease of illustration, and can also be equally applicable to the LEDs 50-1 and 50-2 in a state where the reflective electrodes 56 and 56' are formed.

[0233] In the manufacturing method according to the embodiment of the disclosure, the operation of checking defects of the plurality of LEDs 50-1 and 50-2 can be performed before the operation of connecting the LEDs 50-1 and 50-2 to the driving circuit layer 20 (S540) is performed.

[0234] Referring to FIGS. 3A and 3B, Figure 12A 12B ​​​​​​The lower inspection substrate 1210 and the upper inspection substrate 1220 can be attached to the upper and lower portions of the middle substrate 40 in a state in which a plurality of LEDs 50-1 and 50-2 are combined.

[0235] Here, the inspection substrates 1210 and 1220 can be formed (or manufactured) as structures for evaluating the optical or electrical properties of each of the plurality of LEDs 50-1 and 50-2 combined to the middle substrate 40.

[0236] The lower inspection substrate 1210 can include a base substrate 1211 and a plurality of first electrodes 1218. Here, the plurality of first electrodes 1218 can be arranged in the same manner as the plurality of first electrodes 28 of the driving circuit layer 20 as illustrated in FIG. 13, and can have the same polarity (e.g., anode or cathode).

[0237] The upper inspection substrate 1220 can include a base substrate 1221, an adhesive layer 1223, and a plurality of second electrodes 1229. Here, the plurality of second electrodes 1229 can be arranged in the same manner as the plurality of second electrodes 29 of the driving circuit layer 20 as illustrated in FIG. 13, and can have the same polarity (e.g., anode or cathode). Here, the second electrodes 1229 can be formed along a bar forming the plurality of LEDs 50 to be connected to the plurality of LEDs 50. In addition, a height h2 from a lower surface of the base substrate 1221 to a lower surface of the plurality of second electrodes 1229 can be the same as a height h1 of the LEDs 50-1. This is because when h2 is less than h1, the upper inspection substrate 1220 can pressurize the plurality of LEDs 50-1 and 50-2 and damage the plurality of LEDs 50-1 and 50-2. Accordingly, the height h2 from the lower surface of the base substrate 1221 to the lower surface of the plurality of second electrodes 1229 can be adjusted according to the height h1 of each LED 50-1.

[0238] In this case, as illustrated in FIG. 14, the inspection substrates 1210 and 1220 can generate a driving signal for turning on the plurality of LEDs 50-1 and 50-2, and thus can perform optical inspection or the like that checks whether the plurality of LEDs 50-1 and 50-2 are defective. Figure 12B

[0239] Specifically, the optical inspection can identify whether the plurality of LEDs 50-1 and 50-2 are turned on through an image captured by a vision camera, like automatic optical inspection (AOI).

[0240] ​In particular, when it is identified that unturned LEDs (hereinafter referred to as defective LEDs) occur due to the intervals between the plurality of first electrodes 1218 of the lower inspection substrate 1210 being greater than the intervals between the conductive materials 48, the intermediate substrate 40 corresponding to the area (coordinates) of the defective LEDs can be separated from the lower inspection substrate 1210, and then a force can be applied to the intermediate substrate 40 in the horizontal direction to stretch the intermediate substrate 40 so that the intervals between the conductive materials 48 of the intermediate substrate 40 coincide with the intervals of the plurality of first electrodes 1218 of the lower inspection substrate 1210. This is by the elasticity or stretchability of the intermediate substrate 40. In addition, the intermediate substrate 40 can be attached to the lower inspection substrate 1210 so that the conductive materials 48 of the intermediate substrate 40 contact the plurality of first electrodes 1218 of the lower inspection substrate 1210. Thereafter, the optical inspection can be performed again by the lower inspection substrate 1210 and the upper inspection substrate 1220 attached to the intermediate substrate 40.

[0241] On the other hand, when the defective LEDs are identified, the LEDs and the intermediate substrate 40 corresponding to the identified area can be separated and removed. That is, some areas can be separated from the intermediate substrate 40 by various methods (physical force, chemical method, etc.).

[0242] Here, when the inspection operation is completed, the inspection substrates 1210 and 1220 can be separated from the intermediate substrate 40, as shown in Figure 12A .

[0243] Thereafter, the LEDs 50 can be electrically connected to the driving circuit layer 20 through the conductive materials (S540). This will be described in more detail with reference to Figure 13A to 13E and FIGS. 14A to 14D.

[0244] Figure 13A to 13E is a diagram for describing an operation of bonding the intermediate substrate to the driving circuit layer according to an embodiment of the disclosure.

[0245] Here, Figure 13A is shown a state before the intermediate substrate 40 is bonded to the driving circuit layer 20 according to an embodiment of the disclosure, in which the LEDs 50-1 and 50-2 have a state in which a reflective electrode is not formed on the intermediate substrate 40, that is, a structure in which the light emitting direction is both sides.

[0246] Referring to Figure 13A , the intermediate substrate 40 can be attached to the driving circuit layer 20 disposed on the substrate 10 to electrically connect the first type semiconductor layers 51 of the plurality of LEDs 50 attached on the intermediate substrate 40 to the driving circuit layer 20.

[0247] Here, the driving circuit layer 20 can include a plurality of pixel circuits 21 and the first electrode 28 and the second electrode 29 electrically connected to each of the plurality of pixel circuits 21. Here, the driving circuit layer 20 has been described previously, and thus will not be repeated.

[0248] Specifically, the intermediate substrate 40 can be attached to the driving circuit layer 20 by an adhesive material 43. Here, the intermediate substrate 40 can be attached to the driving circuit layer 20 such that a lower portion of the intermediate substrate 40 is positioned on the driving circuit layer 20 in a state in which the plurality of LEDs 50-1 and 50-2 are bonded to the intermediate substrate 40. The intermediate substrate 40 can be directly bonded to the driving circuit layer 20.

[0249] In this case, the first-type semiconductor layer 51 of each of the plurality of LEDs 50 can be electrically connected to the first electrode 28 of the driving circuit layer 20 through the conductive materials 48 and 58.

[0250] According to an embodiment, the intermediate substrate 40 can be attached to the driving circuit layer 20 by various methods such as roll-to-roll, roll pressing, vacuum pressing, and pressing in which a plate moves in a vertical direction and is pressed. For example, in the case of the roll pressing method, the intermediate substrate 40 on which the LEDs 50 are formed and the driving circuit layer 20 (or the substrate 10 on which the driving circuit layer 20 is formed) can be disposed in one direction. In this case, when a roller presses the intermediate substrate 40 while rotating, the intermediate substrate 40 can be attached to the roller while being wound. When the driving circuit layer 20 is pressed while rotating again, the intermediate substrate 40 attached to the roller can be transferred and attached to the driving circuit layer 20.

[0251] On the other hand, according to an embodiment of the disclosure, when the intermediate substrate 40 is bonded to the driving circuit layer 20 in a state in which the LEDs 50-1 and 50-2 having a structure in which the light emission direction is the top side are formed, the conductive material 48 can be electrically connected to the first electrode 28 of the driving circuit layer 20, and the conductive material 49 can be electrically connected to the second electrode 29 of the driving circuit layer 20, as shown in FIG. 5A. In this case, the first-type semiconductor layer 51 of the LEDs 50-1 and 50-2 can be electrically connected to the first electrode 28 of the driving circuit layer 20 through the reflective electrode 56 formed at the lower portion of the LEDs 50-1 and 50-2 and the conductive materials 58 and 48. Figure 13B

[0252] On the other hand, when the intermediate substrate 40 is bonded to the driving circuit layer 20 in a state in which the LEDs 50-1 and 50-2 having a structure in which the light emission direction is the bottom side are formed, the conductive material 48 can be electrically connected to the first electrode 28 of the driving circuit layer 20, and the conductive material 49 can be electrically connected to the second electrode 29 of the driving circuit layer 20, as shown in FIG. 5B. In this case, the first-type semiconductor layer 51 of the LEDs 50-1 and 50-2 can be electrically connected to the first electrode 28 of the driving circuit layer 20 through the reflective electrode 56 formed at the lower portion of the LEDs 50-1 and 50-2 and the conductive materials 58 and 48. Figure 13C ​As shown, the first-type semiconductor layers 51 of the LEDs 50-1 and 50-2 can be electrically connected to the first electrode 28 of the driving circuit layer 20 through the conductive materials 58 and 48.

[0253] The intermediate substrate 40 according to the embodiment of the disclosure as described above can be directly bonded to the driving circuit layer 20 without other media.

[0254] According to an embodiment, as shown, the intermediate substrate 40 can be attached to the driving circuit layer 20 in units of the pixels 100-1 and 100-2. That is, the intermediate substrate 40 including the LEDs 50 corresponding to the pixels 100-1 and 100-2 can be attached to the driving circuit layer 20. Here, each of the pixels 100-1 and 100-2 can include a single LED 50, or can include a plurality of LEDs 50-1, 50-2, and 50-3. Figure 13D

[0255] As another example, as shown, the intermediate substrate 40 can be attached to the driving circuit layer 20 in units of a column (or a row) of the LEDs 50. That is, the intermediate substrate 40 including at least one column (or row) of the LEDs 50 can be attached to the driving circuit layer 20. Here, the LEDs 50-1, 50-2, and 50-3 corresponding to one column (or row) can be LEDs (i.e., sub-pixels of the same type (color)) formed to emit the same color (e.g., red). Figure 13E

[0256] Accordingly, the display module 1 according to the disclosure and the manufacturing method thereof can improve the transfer speed of the plurality of LEDs 50, and can improve the overall production yield.

[0257] On the other hand, the intermediate substrate 40 can include a prepreg to have elasticity or stretchability and adhesiveness. Accordingly, when a defective LED occurs in the plurality of LEDs 50-1 and 50-2, the defective LED and the intermediate substrate 40 of the portion including the defective LED can be removed together like a sticker. The defect can be repaired by attaching the intermediate substrate 40 in which a plurality of individual LEDs 50-1 and 50-2 are bonded to the portion of the driving circuit layer 20 from which the intermediate substrate 40 is removed.

[0258] Figure 14A to 14D is a diagram for describing a display module manufactured according to an embodiment of the disclosure. Here, Figure 14A is a diagram for describing a structure in which the light emission direction is both sides (e.g., the LEDs 50-1 and 50-2 in a state in which the reflective electrode is not formed) according to an embodiment of the disclosure, Figure 14B ​​is a diagram for describing a structure in which the light emitting direction is a top side (LEDs 50-1 and 50-2 in a state in which a reflective electrode 56 is formed at a lower portion thereof) according to an embodiment of the disclosure, Figure 14C is a diagram for describing a structure in which the light emitting direction is a bottom side (LEDs 50-1 and 50-2 in a state in which a reflective electrode 56' is formed at an upper portion thereof) according to an embodiment of the disclosure, and Figure 14D is a diagram showing the arrangement of a plurality of LEDs 50-1 and 50-2 in a display module.

[0259] Referring to Figure 14A to 14D , the second-type semiconductor layer 55 of the plurality of LEDs 50-1 and 50-2 can be electrically connected to the driving circuit layer 20.

[0260] According to an embodiment, an upper electrode 59 of each of the plurality of LEDs 50-1 and 50-2 can be formed. Here, the upper electrode 59 can include at least one of a carbon nanotube (CNT), graphene, or a metal nanowire, and can also be implemented as a flexible electrode having flexibility. This has been described previously, and is not repeated here.

[0261] Here, the upper electrode 59 can be formed by various methods, such as a spray method (e.g., spraying), a lamination method, photolithography, MOVPE, MOCVD, and MBE.

[0262] Specifically, the upper electrode 59 can be formed along the side surface of the LED 50. In this case, the second-type semiconductor layer 55 can be electrically connected to the second electrode 29 of the driving circuit layer 20 through the transparent electrode 59 and the conductive material 49 of the intermediate substrate 40.

[0263] According to an embodiment of the disclosure, the upper electrode 59 of each of the plurality of LEDs 50-1 and 50-2 can be formed along the passivation 57. In this case, the second-type semiconductor layer 55 of each of the plurality of LEDs 50-1 and 50-2 can be electrically connected to the second electrode 29 of the driving circuit layer 20 through the upper electrode 59.

[0264] Meanwhile, as an example of the disclosure, when the light emitting direction is both sides as shown in Figure 14A or a top side as shown in Figure 14B , the upper electrode 59 can be configured as a transparent electrode having high light transmittance and conductivity.

[0265] For example, according to the structure of the CNT (e.g., single-walled CNT (SW-CNT), multi-walled CNT (MW-CNT), etc.), the diameter of the CNT, the molecular length of the CNT, the concentration (or density) of the CNT, and the density of a mixed material (e.g., Ag nanowire, etc.), the upper electrode 59 can include a CNT having high conductivity and transparent properties.

[0266] On the other hand, when the light emitting direction is the bottom side as shown in FIG. 1B, the upper electrode 59 can be configured as an electrode having a high conductive property. At this time, the upper electrode 59 does not need to be made of a material having a high light transmittance since it is not a path of light travel, but is not limited thereto and can be made of various materials. Figure 14C

[0267] As described above, in the manufacturing method of the display module 1 according to the embodiment of the disclosure, the display module 1 having a stepless bottom contact structure can be manufactured, unlike the flip chip structure which needs a protrusion (bump or pad (electrode)) between the driving circuit layer 20 and the LED 50 to electrically connect the driving circuit layer 20 and the LED 50.

[0268] Here, the display module 1 having a stepless bottom contact structure does not need to form a protrusion such as a pad and a bump by providing a step on the lower surface of each of the first-type semiconductor layer 51 and the second-type semiconductor layer 55 of the LED 50 since the display module 1 having a stepless bottom contact structure can electrically connect the driving circuit layer 20 and the LED 50 through the intermediate substrate 40. That is, the intermediate substrate 40 can replace the protrusion such as a pad and a bump.

[0269] Accordingly, the display module 1 having a stepless bottom contact structure can maximize the area of the first-type semiconductor layer 51 and the second-type semiconductor layer 55, and thus the light emitting area of the light emitting layer 53 formed between the first-type semiconductor layer 51 and the second-type semiconductor layer 55 can be maximized to improve light emitting efficiency.

[0270] In addition, the display module 1 having a stepless bottom contact structure can prevent the risk of short circuit of two electrodes since the two electrodes (or pads) of the LED 50 are formed at different positions (e.g., the upper and lower portions of the LED 50). In particular, when the LED 50 is miniaturized, the stepless bottom contact structure in which the two electrodes are located at the upper and lower portions of the LED 50 can effectively prevent the risk of short circuit compared to the flip chip structure in which the two electrodes are located at the lower portion of the LED 50.

[0271] Figure 15 FIG. 1C is a diagram for describing a black matrix according to an embodiment of the disclosure.

[0272] Referring to Figure 15 , the manufacturing method according to the embodiment of the disclosure can further include an operation of forming a black matrix 60 in a region between the plurality of LEDs 50-1 and 50-2 on the intermediate substrate 40.

[0273] ​Here, the black matrix 60 can include a material that absorbs light and exhibits black. Also, the black matrix 60 can include a material having a high resistance property (or an insulating property). According to an embodiment, the black matrix 60 can include various materials such as CNT, polymer, and metal oxide, and can be formed by a spray method, a lamination method, MOCVD, MOVPE, MBE deposition, etc.

[0274] In particular, when CNT is used as the black matrix 60, according to the structure of the CNT (e.g., single-walled CNT (SW-CNT), multi-walled CNT (MW-CNT), etc.), the diameter of the CNT, the molecular length of the CNT, the concentration (or density) of the CNT, and the density of a mixed material (e.g., Ag nanowire, etc.), CNT having low conductivity and light absorption properties can be used.

[0275] Accordingly, the manufacturing method according to an embodiment of the disclosure has the effect that the black matrix 60 can be formed through a simpler process, and the black matrix 60 having excellent external light absorption properties can be formed.

[0276] According to various embodiments of the disclosure as described above, it is possible to provide a display module and a manufacturing method thereof that solve various problems such as a decrease in yield, a non-emission rate, and a defect rate of a related art μ-LED process, while alleviating the limitations of a related art μ-LED structure.

[0277] In addition, according to one or more embodiments of the disclosure, by simplifying the process to solve the yield decrease and solve the process problems such as short circuit occurrence and non-emission defects, it is possible to expect the effects of reducing costs and improving reliability.

[0278] Although the accompanying drawings attached to the disclosure are provided to help understand the technical spirit of the disclosure, the technical spirit of the disclosure is not limited by the relative sizes or intervals of various elements, regions, etc. shown in the drawings.

[0279] One or more embodiments of the disclosure can be implemented by software including instructions stored in a machine (e.g., computer)-readable storage medium. The machine is a device that calls stored instructions from the storage medium and operates according to the called instructions, and can include an electronic device according to the disclosed embodiments. When the processor executes the command, the processor can directly or using other components under the control of the processor perform a function corresponding to the command. The command can include code generated or executed by a compiler or an interpreter. The machine-readable storage medium can be provided in the form of a non-transitory storage medium. Here, the term "non-transitory" means that the storage medium does not include a signal and is tangible, but does not distinguish whether data is stored in the storage medium semi-permanently or temporarily.

[0280] The method according to one or more embodiments can be provided as an inclusion in a computer program product. The computer program product can be traded as a product between a seller and a buyer. The computer program product can be distributed in the form of a machine-readable storage medium (e.g., an optical disc read-only memory (CD-ROM)) or distributed online through an app store (e.g., PlayStore™). In the case of online distribution, at least a portion of the computer program product can be at least temporarily stored or temporarily generated in a storage medium, such as the memory of a manufacturer's server, an app store's server, or a relay server.

[0281] Each component (e.g., a module or program) according to one or more embodiments may include a single entity or multiple entities, and some of the sub-components described above may be omitted, or other sub-components may be included in one or more embodiments. Alternatively or additionally, some components (e.g., modules or programs) may be integrated into one entity to perform the same or similar functions performed by the individual components prior to integration. Operations performed by modules, programs, or other components according to one or more embodiments may be performed sequentially, in parallel, iteratively, or heuristically, or at least some operations may be performed in a different order or omitted, or additional operations may be added.

[0282] While embodiments of this disclosure have been described and illustrated above, this disclosure is not limited to the specific embodiments described above. Various modifications can be made by those skilled in the art to which this disclosure pertains without departing from the scope and spirit of this disclosure as claimed in the appended claims. Such modifications should not be interpreted solely from the technical spirit or prospects of this disclosure.

Claims

1. A method of manufacturing a display module, the method comprising: forming an epitaxial film including a light emitting layer, a first conductive type semiconductor layer, and a second conductive type semiconductor layer; attaching the epitaxial film to an intermediate substrate including a first conductive part, a second conductive part, and an adhesive part disposed in different regions, respectively; patterning the epitaxial film to form a light emitting diode (LED); and attaching the intermediate substrate to a driving circuit layer formed on a substrate to electrically connect the LED to the driving circuit layer after forming the LED, wherein attaching the intermediate substrate to the driving circuit layer formed on the substrate to electrically connect the LED to the driving circuit layer after forming the LED comprises: electrically connecting the first conductive type semiconductor layer of the LED to the driving circuit layer through the first conductive part, wherein the intermediate substrate is attached to the driving circuit layer through the adhesive part. 2.The method of claim 1, wherein the LED has a vertical structure, and each of the first conductive part and the second conductive part includes at least one of a carbon nanotube (CNT), graphene, or a metal nanowire. 3.The method of claim 2, wherein the driving circuit layer includes a pixel circuit and a first electrode and a second electrode coupled to the pixel circuit to electrically connect the first electrode and the second electrode to the pixel circuit. 4.The method of claim 3, further comprising forming a passivation element on a sidewall of the LED.

5. The method of claim 4, wherein connecting the second conductivity type semiconductor layer of the LED to the drive circuit layer comprises: forming a transparent electrode along the passivation element; and wherein the second conductive type semiconductor layer of the LED is electrically connected to the second electrode of the driving circuit layer through the transparent electrode and the second conductive part. 6.The method of claim 5, further comprising forming a black matrix in a region between the LED and another LED on the intermediate substrate. 7.The method of claim 3, wherein the first conductive type semiconductor layer of the LED is electrically connected to the first electrode of the driving circuit layer through the first conductive part. 8.The method of claim 1, wherein the adhesive part includes at least one of an epoxy resin, a polyimide, or a phenol. 9.The method of claim 1, further comprising forming a reflective electrode at a lower portion of the first conductive type semiconductor layer or an upper portion of the second conductive type semiconductor layer. 10.A display module comprising: a substrate; a driving circuit layer disposed on the substrate, the driving circuit layer including a pixel circuit and a plurality of electrodes configured to be electrically connected to the pixel circuit, wherein the plurality of electrodes includes a first electrode and a second electrode; an intermediate substrate including a first layer and a second layer, wherein the first layer includes a first conductive part, a second conductive part, and an adhesive part disposed in different regions, respectively, and the second layer includes a conductive material, the intermediate substrate being attached to the driving circuit layer through the adhesive part; a light emitting diode (LED) disposed on the second layer of the intermediate substrate, ​ wherein the LED includes a light emitting layer, and first and second conductive type semiconductor layers disposed at upper and lower portions of the light emitting layer, respectively, and wherein the intermediate substrate is attached to the driving circuit layer through the adhesive portion to electrically connect the first conductive type semiconductor layer of the LED to the first electrode of the driving circuit layer through the second layer and the first conductive portion. 11.The display module of claim 10, wherein the LED has a vertical structure. 12.The display module of claim 11, further comprising a passivation element disposed on a sidewall of the LED. 13.The display module of claim 12, wherein the LED further includes a transparent electrode disposed along the passivation element, and the second conductive type semiconductor layer is configured to be electrically connected to the second electrode through the transparent electrode. 14.The display module of claim 13, further comprising a black matrix disposed in an area between the LED and another LED on the intermediate substrate.

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