LED display device

Abstract

To provide a display device.SOLUTION: A display device includes a display substrate, a plurality of light emitting elements arranged on the display substrate, and a molding layer that covers the sides of each light emitting element and exposes the top surface, the light emitting element includes a first LED subunit, a second LED subunit arranged on the first LED subunit, and a third LED subunit arranged on the second LED subunit, and the third LED subunit is arranged closer to the top surface of the light emitting element than the first LED subunit.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] This disclosure relates to display devices, and more particularly to LED display devices. [Background technology]

[0002] Light-emitting diodes (LEDs) are inorganic light sources that are widely used in many fields, including display devices, vehicle lamps, and general lighting. Because LEDs have advantages such as a long lifespan, low power consumption, and fast response speed, they are rapidly replacing existing light sources.

[0003] On the other hand, conventional light-emitting diodes (LEDs) have primarily been used as backlight sources in display devices. However, in recent years, LED displays that directly generate images using LEDs have been developed.

[0004] Display devices generally use mixtures of blue, green, and red to achieve a wide range of hues. To create diverse images, a display device contains multiple pixels, each containing blue, green, and red subpixels. The hue of a particular pixel is determined through the hues of these subpixels, and the combination of these pixels creates an image.

[0005] LEDs can emit light of various hues depending on their material, so a display device can be provided by arranging individual LED chips that emit blue, green, and red light on a two-dimensional plane. However, if one LED chip is arranged for each subpixel, the number of LED chips increases, and the assembly process takes a long time.

[0006] Since each subpixel is arranged on a two-dimensional plane, the area occupied by a single pixel containing blue, green, and red subpixels becomes relatively large. Therefore, in order to arrange each subpixel within a limited area, the area of ​​each LED chip must be reduced. However, reducing the size of the LED chip may make LED chip mounting difficult and further reduce the light-emitting area.

[0007] On the other hand, display devices that can achieve a wide range of hues need to stably provide high-quality white light. Conventional TVs used an RGB mixing ratio of 3:6:1 to achieve standard D65 white light. That is, the luminosity of red was relatively higher than that of blue, and the luminosity of green was relatively the highest. However, currently used LED chips generally have a relatively high luminosity for blue LEDs compared to other LEDs, which presents a problem in matching the RGB mixing ratio in display devices using each LED chip.

[0008] Furthermore, if the viewing angles of the blue, green, and red light emitted from a single pixel are wide, interference with adjacent pixels may occur, making it difficult to achieve sharp image quality. Moreover, if the viewing angles of the blue, green, and red light emitted from a single pixel are different from each other, an image with a different RGB mixing ratio will be created depending on the viewing angle. [Overview of the project] [Problems that the invention aims to solve]

[0009] The problem that this disclosure aims to solve is to provide a display device that can increase the area of ​​each subpixel within a limited pixel area.

[0010] Another problem that this disclosure aims to solve is to provide a display device that can shorten the mounting process time for light-emitting elements.

[0011] Another problem that this disclosure aims to solve is to provide a display device that allows for easy control of the RGB mixing ratio.

[0012] Another problem that this disclosure seeks to solve is to provide a display device that can narrow the viewing angle of light of various hues emitted from within a single pixel.

[0013] Another problem that this disclosure seeks to solve is to provide a display device that can make the viewing angles of light of various hues emitted from within a single pixel the same. [Means for solving the problem]

[0014] A display device according to one embodiment of the present disclosure includes a display substrate, a plurality of light-emitting elements disposed on the display substrate, and a molding layer that covers the sides of each light-emitting element and exposes its upper surface, wherein the light-emitting element includes a first LED subunit, a second LED subunit disposed on the first LED subunit, and a third LED subunit disposed on the second LED subunit, the third LED subunit being positioned closer to the upper surface of the light-emitting element than the first LED subunit.

[0015] A display device according to another embodiment of the present disclosure includes a display substrate, a plurality of light-emitting elements disposed on the display substrate, and a molding layer that covers the sides of each light-emitting element and exposes its upper surface, wherein the light-emitting elements include a first light-emitting stack that emits red light, a second light-emitting stack disposed on the first light-emitting stack that emits blue light, and a third light-emitting stack disposed on the second light-emitting stack that emits green light, wherein the third light-emitting stack is disposed near the upper surface of the light-emitting elements, and the molding layer blocks the light emitted from the first to third light-emitting stacks. [Brief explanation of the drawing]

[0016] [Figure 1A] This is a schematic perspective view illustrating a light-emitting element according to one embodiment of the present disclosure. [Figure 1B]It is a schematic plan view of the light-emitting element of FIG. 1A. [Figure 1C] It is a schematic cross-sectional view taken along the A-A' line of FIG. 1B. [Figure 1D] It is a schematic cross-sectional view taken along the B-B' line of FIG. 1B. [Figure 2] It is a schematic cross-sectional view of a light-emitting stack structure according to an embodiment of the present disclosure. [Figure 3A] It is a plan view showing the process of manufacturing the light-emitting element of FIG. 1A according to an exemplary embodiment. [Figure 3B] It is a cross-sectional view along the A-A' line of the corresponding plan view shown in FIG. 3A according to an exemplary embodiment. [Figure 3C] It is a cross-sectional view along the B-B' line of the corresponding plan view shown in FIG. 3A according to an exemplary embodiment. [Figure 4A] It is a plan view showing the process of manufacturing the light-emitting element of FIG. 1A according to an exemplary embodiment. [Figure 4B] It is a cross-sectional view along the A-A' line of the corresponding plan view shown in FIG. 4A according to an exemplary embodiment. [Figure 4C] It is a cross-sectional view along the B-B' line of the corresponding plan view shown in FIG. 4A according to an exemplary embodiment. [Figure 5A] It is a plan view showing the process of manufacturing the light-emitting element of FIG. 1A according to an exemplary embodiment. [Figure 5B] It is a cross-sectional view along the A-A' line of the corresponding plan view shown in FIG. 5A according to an exemplary embodiment. [Figure 5C] It is a cross-sectional view along the B-B' line of the corresponding plan view shown in FIG. 5A according to an exemplary embodiment. [Figure 6A] It is a plan view showing the process of manufacturing the light-emitting element of FIG. 1A according to an exemplary embodiment. [Figure 6B] It is a cross-sectional view along the A-A' line of the corresponding plan view shown in FIG. 6A according to an exemplary embodiment. [Figure 6C] It is a cross-sectional view along the B-B' line of the corresponding plan view shown in FIG. 6A according to an exemplary embodiment. [Figure 7A]This is a plan view showing the process of manufacturing the light-emitting element of Figure 1A according to an exemplary embodiment. [Figure 7B] This is a cross-sectional view along the line A-A' in the corresponding plan view shown in Figure 7A, which embodies an exemplary embodiment. [Figure 7C] This is a cross-sectional view along the line B-B' in the corresponding plan view shown in Figure 7A, which embodies an exemplary embodiment. [Figure 8A] This is a plan view showing the process of manufacturing the light-emitting element of Figure 1A according to an exemplary embodiment. [Figure 8B] This is a cross-sectional view along the line A-A' in the corresponding plan view shown in Figure 8A, which embodies an exemplary embodiment. [Figure 8C] This is a cross-sectional view along the line B-B' in the corresponding plan view shown in Figure 8A, which embodies an exemplary embodiment. [Figure 9] This is a schematic cross-sectional view showing the manufacturing process of the light-emitting element shown in Figure 1A, according to an exemplary embodiment. [Figure 10] This is a schematic cross-sectional view showing the manufacturing process of the light-emitting element shown in Figure 1A, according to an exemplary embodiment. [Figure 11] This is a schematic cross-sectional view showing the manufacturing process of the light-emitting element shown in Figure 1A, according to an exemplary embodiment. [Figure 12] This is a schematic cross-sectional view showing the manufacturing process of the light-emitting element shown in Figure 1A, according to an exemplary embodiment. [Figure 13] This is a schematic cross-sectional view showing the manufacturing process of the light-emitting element shown in Figure 1A, according to an exemplary embodiment. [Figure 14] This is a schematic cross-sectional view showing a manufacturing process for a light-emitting package according to one embodiment of the present disclosure. [Figure 15] This is a schematic cross-sectional view showing a manufacturing process for a light-emitting package according to one embodiment of the present disclosure. [Figure 16A] This is a schematic cross-sectional view showing a manufacturing process for a light-emitting package according to one embodiment of the present disclosure. [Figure 16B] This is a schematic cross-sectional view showing a manufacturing process for a light-emitting package according to one embodiment of the present disclosure. [Figure 17]This is a schematic cross-sectional view illustrating a display device according to one embodiment of the present disclosure. [Figure 18] This is a schematic cross-sectional view illustrating a light-emitting package according to other embodiments of the present disclosure. [Figure 19A] This graph shows the viewing angle of a light-emitting element when a molding layer related to conventional technology is not used. [Figure 19B] This is a graph showing the viewing angle of a light-emitting element when a transparent molding layer is used according to one embodiment of the present disclosure. [Figure 19C] This is a graph showing the viewing angle of a light-emitting element when a black molding layer is used according to one embodiment of this disclosure. [Modes for carrying out the invention]

[0017] The embodiments of this disclosure will be described in detail below with reference to the attached drawings. The embodiments described below are provided as examples to adequately convey the ideas of this disclosure to a person ordinary in the art to which this disclosure pertains. Therefore, this disclosure is not limited to the embodiments described below and can be embodied in other forms. In the drawings, the width, length, thickness, etc., of components may be exaggerated for convenience. Also, when a component is described as being "above" or "on top of" another component, this includes not only cases where each part is "directly above" or "on top of" the other part, but also cases where other components are interposed between each component and the other components. The same reference numeral throughout the specification indicates the same component.

[0018] A display device according to one embodiment of the present disclosure includes a display substrate, a plurality of light-emitting elements disposed on the display substrate, and a molding layer that covers the sides of each light-emitting element and exposes its upper surface, wherein the light-emitting element includes a first LED subunit, a second LED subunit disposed on the first LED subunit, and a third LED subunit disposed on the second LED subunit, the third LED subunit being positioned closer to the upper surface of the light-emitting element than the first LED subunit.

[0019] Since the first to third LED subunits overlap each other, the area of ​​each subpixel can be increased within a limited pixel area without increasing the overall pixel area. Furthermore, because the light-emitting element includes the first to third LED subunits, the number of light-emitting elements can be reduced compared to conventional light-emitting elements, and as a result, the mounting process time for the light-emitting elements can be shortened.

[0020] Furthermore, since the molding layer covers the sides of the light-emitting element and exposes the top surface, the viewing angle of the light emitted from the first to third LED subunits can be narrowed, and the viewing angles of the light emitted from the first to third LED subunits can be made almost identical.

[0021] In one embodiment, the molding layer can block light by reflecting or absorbing light emitted from the light-emitting element.

[0022] On the other hand, the first, second, and third LED subunits can emit red light, blue light, and green light, respectively. The second subunit emits blue light and the third subunit emits green light, thereby increasing the luminosity of the green light, and as a result, an RGB mixing ratio suitable for a display device can be easily provided.

[0023] The first LED subunit may include a first light-emitting stack, the second LED subunit may include a second light-emitting stack, and the third LED subunit may include a third light-emitting stack. Each of the first, second, and third light-emitting stacks may include a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer.

[0024] In one embodiment, the upper surface of the molding layer may be aligned with the upper surface of the first conductivity type semiconductor layer of the third light-emitting stack.

[0025] In other embodiments, the light-emitting element may further include a substrate disposed on the third LED subunit, and the upper surface of the molding layer may be aligned with the upper surface of the substrate.

[0026] The light-emitting element may further include a first bonding layer interposed between the first LED subunit and the second LED subunit, and a second bonding layer interposed between the second LED subunit and the third LED subunit.

[0027] Furthermore, the light-emitting element may further include a first connecting electrode electrically connected to the first LED subunit, a second connecting electrode electrically connected to the second LED subunit, a third connecting electrode electrically connected to the third LED subunit, and a fourth connecting electrode electrically connected in common to the first, second, and third LED subunits.

[0028] Furthermore, the light-emitting element may further include a protective layer surrounding at least a portion of the first to fourth connecting electrodes.

[0029] The protective layer may include an epoxy molding compound or a polyimide film, and the lower surface of the protective layer may be aligned with the lower surfaces of the first to fourth connecting electrodes.

[0030] The display device may further include a circuit board interposed between the display substrate and the light-emitting element, the first to fourth connecting electrodes may be bonded to the circuit board, and the molding layer may be arranged on the circuit board.

[0031] The lower surfaces of the first, second, third, and fourth connecting electrodes may be larger than their respective upper surfaces.

[0032] Furthermore, the first connecting electrode, the second connecting electrode, and the third connecting electrode may be electrically connected to the second conductivity type semiconductor layer of the first light-emitting stack, the second light-emitting stack, and the third light-emitting stack, respectively, and the fourth connecting electrode may be electrically connected to the first conductivity type semiconductor layer of the first to third light-emitting stacks in common.

[0033] On the other hand, the first LED subunit may include a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, and an upper contact electrode that makes ohmic contact with the first conductivity type semiconductor layer, wherein the first conductivity type semiconductor layer includes a recessed portion, and the upper contact electrode may be formed within the recessed portion of the first conductivity type semiconductor layer.

[0034] Furthermore, the light-emitting element may include first to third lower contact electrodes that contact the second conductivity type semiconductor layer of the first to third light-emitting stacks, and a first insulating layer having first to third contact holes that partially expose the first to third lower contact electrodes. The first insulating layer may have sub-contact holes arranged on the first conductivity type semiconductor layer of the first to third light-emitting stacks, and the sub-contact holes may be spaced apart from each other.

[0035] Furthermore, the system may include first to third pads superimposed on the first to third contact holes, and a fourth pad superimposed on each of the sub-contact holes, and the first to fourth connecting electrodes may be electrically connected to the first to fourth pads, respectively.

[0036] A display device according to yet another embodiment of the present disclosure includes a display substrate, a plurality of light-emitting elements disposed on the display substrate, and a molding layer covering the sides of each light-emitting element and exposing its upper surface, wherein the light-emitting elements include a first light-emitting stack that emits red light, a second light-emitting stack disposed on the first light-emitting stack that emits blue light, and a third light-emitting stack disposed on the second light-emitting stack that emits green light, wherein the third light-emitting stack is disposed near the upper surface of the light-emitting elements, and the molding layer blocks the light emitted from the first to third light-emitting stacks.

[0037] Furthermore, the light-emitting element may further include a substrate disposed on the third light-emitting stack, and the molding layer may cover the sides of the substrate and expose the top surface of the substrate.

[0038] In one embodiment, the light-emitting element may further include first to third connecting electrodes electrically connected to each p-type semiconductor layer of the first to third light-emitting stacks, and a fourth connecting electrode electrically connected in common to each n-type semiconductor layer of the first to third light-emitting stacks.

[0039] Furthermore, the light-emitting element may further include a protective layer that at least partially covers the sides of each connecting electrode.

[0040] Hereinafter, embodiments of this disclosure will be specifically described with reference to the drawings. In the following, the light-emitting stack structure, light-emitting element, or light-emitting package may include a micro-LED, which has a light-emitting area of ​​10,000 μm² as is known in the art. 2 The following is the case. In other embodiments, the micro-LED is 4000 μm 2 Furthermore, 2500 μm 2 The following light-emitting areas may be included.

[0041] Figure 1A is a schematic perspective view illustrating a light-emitting element according to one embodiment of the present disclosure; Figure 1B is a schematic plan view of the light-emitting element of Figure 1A; and Figures 1C and 1D are schematic cross-sectional views taken along the lines A-A' and B-B' of Figure 1B, respectively.

[0042] Referring to Figures 1A and 1B, the light-emitting element 100 includes a light-emitting stack structure, a first connection electrode 20ce, a second connection electrode 30ce, a third connection electrode 40ce, and a fourth connection electrode 50ce formed on the light-emitting stack structure, and a protective layer 90 surrounding each of the connection electrodes 20ce, 30ce, 40ce, and 50ce. An array of each light-emitting element 100 may be formed on the substrate 11, and the light-emitting element 100 shown exemplarily in Figure 1A shows a single unit formed from such an array, and can therefore be referred to as a light-emitting element. The formation and single-unit formation of each light-emitting element 100 will be described in detail later. In some embodiments, the light-emitting element 100 including the light-emitting stack structure may be further processed to be formed into a light-emitting package, which will also be described in detail later.

[0043] Referring to Figures 1A to 1D, the light-emitting element 100 according to the illustrated embodiment includes a light-emitting stack structure, which may include a first LED subunit, a second LED subunit, and a third LED subunit arranged on a substrate. The first LED subunit may include a first light-emitting stack 20, the second LED subunit may include a second light-emitting stack 30, and the third LED subunit may include a third light-emitting stack 40. The light-emitting stack structure shows three light-emitting stacks 20, 30, and 40, but this disclosure is not limited to a specific number of light-emitting stacks. For example, in some embodiments, the light-emitting stack structure may include two or more light-emitting stacks. Here, the light-emitting element 100 is described with respect to a light-emitting stack structure that includes three light-emitting stacks 20, 30, and 40 according to one embodiment.

[0044] The substrate 11 may contain a light-transmitting insulating material to allow light to pass through. However, in some embodiments, the substrate 11 may be formed to be semi-transparent so as to transmit only light of a specific wavelength, or only a portion of light of a specific wavelength, or it may be formed to be partially transparent. The substrate 11 may be a growth substrate on which the third light-emitting stack 40 can be epitaxially grown, for example, a sapphire substrate. However, the substrate 11 is not limited to a sapphire substrate and may contain a variety of other transparent insulating materials. For example, the substrate 11 may contain glass, quartz, silicon, organic polymer, or organic-inorganic composite material, for example, silicon carbide (SiC), gallium nitride (GaN), indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), aluminum nitride (AlN), gallium oxide (Ga2O3), or a silicon substrate. The substrate 11 may also have irregularities on its upper surface, for example, a patterned sapphire substrate. By including irregularities on the upper surface, the efficiency of extracting light generated by the third light-emitting stack 40 in contact with the substrate 11 can be increased. The irregularities on the substrate 11 may be used to selectively increase the luminosity of the third light-emitting stack 40 compared to the first light-emitting stack 20 and the second light-emitting stack 30. On the other hand, in other embodiments, the substrate 11 may be removed. By removing the substrate 11, the viewing angle of the light emitted from the first to third light-emitting stacks 20, 30, and 40 can be narrowed, as will be described later.

[0045] The first, second, and third light-emitting stacks 20, 30, and 40 are configured to emit light toward the substrate 11. Thus, light emitted from the first light-emitting stack 20 can pass through the second and third light-emitting stacks 30 and 40. According to one embodiment, the first, second, and third light-emitting stacks 20, 30, and 40 can emit light with different peak wavelengths. In one embodiment, light loss can be reduced by having a light-emitting stack farther away from the substrate 11 emit light with a longer wavelength than a light-emitting stack closer to the substrate 11. In another embodiment, the second light-emitting stack 30 can emit light with a shorter wavelength than the third light-emitting stack 40 in order to adjust the color mixing ratio of the first, second, and third light-emitting stacks 20, 30, and 40. This can decrease the luminosity of the second light-emitting stack 30 and increase the luminosity of the third light-emitting stack 40, thereby dramatically changing the luminosity ratio of the light emitted from the first, second, and third light-emitting stacks. For example, the first light-emitting stack 20 may be configured to emit red light, the second light-emitting stack 30 to emit blue light, and the third light-emitting stack 40 to emit green light. This allows for a relative decrease in the intensity of the blue light and a relative increase in the intensity of the green light, making it easy to adjust the ratio of red, green, and blue light intensities to approach 3:6:1. Furthermore, the light-emitting area of ​​the first, second, and third light-emitting stacks 20, 30, and 40 is approximately 10,000 μm². 2 The following is also acceptable, and furthermore, 4000 μm 2 Furthermore, 2500 μm 2 The following is also possible. Furthermore, the closer the third light-emitting stack 40 that emits green light is to the substrate 11, the larger the light-emitting area will be, and the luminosity of the green light can be further increased by placing the third light-emitting stack 40 that emits green light as close to the substrate 11 as possible.

[0046] The first light-emitting stack 20 includes a first conductivity semiconductor layer 21, an active layer 23, and a second conductivity semiconductor layer 25. According to one embodiment, the first light-emitting stack 20 may include, but is not limited to, a red light-emitting semiconductor material such as AlGaAs, GaAsP, AlGaInP, and GaP.

[0047] The first upper contact electrode 21n is positioned on the first conductivity semiconductor layer 21 and can form ohmic contact with the first conductivity semiconductor layer 21. The first lower contact electrode 25p may be positioned below the second conductivity semiconductor layer 25. According to one embodiment, a portion of the first conductivity semiconductor layer 21 may be patterned and recessed, and the first upper contact electrode 21n may be positioned in the recessed region of the first conductivity semiconductor layer 21 to increase the ohmic contact level. The first upper contact electrode 21n may have a single-layer or multi-layer structure and may include, but is not limited to, Al, Ti, Cr, Ni, Au, Ag, Sn, W, Cu, or alloys thereof, such as an Au-Te alloy or an Au-Ge alloy. In one embodiment, the first upper contact electrode 21n may have a thickness of about 100 nm and may include a metal with high reflectivity to increase the light emission efficiency in the downward direction toward the substrate 11.

[0048] The second light-emitting stack 30 includes a first conductivity semiconductor layer 31, an active layer 33, and a second conductivity semiconductor layer 35. According to one embodiment, the second light-emitting stack 30 may include, but is not limited to, a semiconductor material that emits blue light, such as GaN, InGaN, or ZnSe. The second lower contact electrode 35p is located below the second conductivity semiconductor layer 35 of the second light-emitting stack 30.

[0049] The third light-emitting stack 40 includes a first conductivity semiconductor layer 41, an active layer 43, and a second conductivity semiconductor layer 45. According to one embodiment, the third light-emitting stack 40 may include a semiconductor material that emits green light, such as GaN, InGaN, GaP, AlGaInP, or AlGaP. The third lower contact electrode 45p is placed on the second conductivity semiconductor layer 45 of the third light-emitting stack 40.

[0050] According to one embodiment, each of the first conductivity type semiconductor layers 21, 31, 41 and the second conductivity type semiconductor layers 25, 35, 45 of the first, second, and third light-emitting stacks 20, 30, 40 may have a single-layer structure or a multi-layer structure, and in some embodiments, may include a superlattice layer. Furthermore, each of the active layers 23, 33, 43 of the first, second, and third light-emitting stacks 20, 30, 40 may have a single quantum well structure or a multi-quantum well structure.

[0051] Each of the first, second, and third lower contact electrodes 25p, 35p, and 45p may contain a transparent conductive material that transmits light. For example, each lower contact electrode 25p, 35p, and 45p may contain, but is not limited to, a transparent conductive oxide (TCO), such as SnO, InO2, ZnO, ITO, or ITZO.

[0052] The first adhesive layer 61 is positioned between the first light-emitting stack 20 and the second light-emitting stack 30, and the second adhesive layer 63 is positioned between the second light-emitting stack 30 and the third light-emitting stack 40. The first and second adhesive layers 61 and 63 may contain a light-transmitting nonconductive material. For example, the first and second adhesive layers 61 and 63 may contain an optically transparent adhesive (OCA), which may, but is not limited to, epoxy, polyimide, SU8, spin-on glass (SOG), and benzocyclobutene (BCB).

[0053] According to the illustrated embodiment, the first insulating layer 81 and the second insulating layer 83 are arranged on at least a portion of each side surface of the first, second, and third light-emitting stacks 20, 30, and 40. At least one of the first and second insulating layers 81 and 83 is made of a variety of organic or inorganic insulating materials, such as polyimide, SiO2, and SiN. xIt may also contain Al2O3, etc. For example, at least one of the first and second insulating layers 81, 83 may include a distributed Bragg reflector (DBR). As another example, at least one of the first and second insulating layers 81, 83 may include a black organic polymer. In some embodiments, electrically floating metal reflective layers are placed on the first and second insulating layers 81, 83 to reflect light emitted from each light-emitting stack 20, 30, 40 towards the substrate 11. In some embodiments, at least one of the first and second insulating layers 81, 83 may have a single-layer structure or a multi-layer structure formed of two or more insulating layers having different refractive indices.

[0054] According to one embodiment, each of the first, second, and third light-emitting stacks 20, 30, and 40 can be driven independently. More specifically, a common voltage may be applied to one of the first and second conductivity type semiconductor layers of each light-emitting stack, or an individual light-emitting signal may be applied to the other of the first and second conductivity type semiconductor layers of each light-emitting stack. For example, according to one embodiment of the present disclosure, the first conductivity type semiconductor layers 21, 31, and 41 of each light-emitting stack may be n-type, and the second conductivity type semiconductor layers 25, 35, and 45 may be p-type. In this case, the third light-emitting stack 40 may have a stacking sequence in the opposite direction to the first light-emitting stack 20 and the second light-emitting stack 30, resulting in the p-type semiconductor layer 45 being placed on top of the active layer 43, which can simplify the manufacturing process. Hereinafter, the illustrated embodiments can be represented by changing the first and second conductivity type semiconductor layers to n-type and p-type, respectively. Furthermore, the n-type and p-type may be interchangeable.

[0055] The first, second, and third lower contact electrodes 25p, 35p, and 45p, respectively, connected to the p-type semiconductor layers 25, 35, and 45 of each light-emitting stack, are electrically connected to the first to third connecting electrodes 20ce, 30ce, and 40ce, respectively, and can receive the corresponding light-emitting signals. On the other hand, the n-type semiconductor layers 21, 31, and 41 of each light-emitting stack may be electrically connected in common to the fourth connecting electrode 50ce. Thus, the light-emitting element 100 may have a common n-type light-emitting stack structure in which the n-type semiconductor layers 21, 31, and 41 of the first, second, and third light-emitting stacks 20, 30, and 40 are commonly connected, and they may be driven independently of each other. Because it has a common n-type light-emitting stack structure, the sources of the voltages applied to the first, second, and third light-emitting stacks 20, 30, and 40 can be made different from each other.

[0056] The light-emitting element 100 according to the illustrated embodiment has a common n-type structure, but the disclosure is not limited thereto. For example, in some exemplary embodiments, the first conductivity type semiconductor layers 21, 31, and 41 of each light-emitting stack may be p-type, and the second conductivity type semiconductor layers 25, 35, and 45 of each light-emitting stack may be n-type, thus forming a common p-type light-emitting stack structure. Furthermore, in some embodiments, the stacking sequence of each light-emitting stack is not limited to that shown in the drawings and can be varied in many ways. Hereinafter, the light-emitting element 100 according to one embodiment of the disclosure will be described with reference to a common p-type light-emitting stack structure.

[0057] According to the illustrated embodiment, the light-emitting element 100 includes a first pad 20pd, a second pad 30pd, a third pad 40pd, and a fourth pad 50pd. The first pad 20pd is electrically connected to a first lower contact electrode 25p via a first contact hole 20CH defined through a first insulating layer 81. The first connecting electrode 20ce is electrically connected to the first pad 20pd via a first through-hole 20ct defined through a second insulating layer 83. The second pad 30pd is electrically connected to a second lower contact electrode 35p via a second contact hole 30CH defined through the first insulating layer 81. The second connecting electrode 30ce is electrically connected to a second pad 30pd via a second through-hole 30ct defined through the second insulating layer 83.

[0058] The third pad 40pd is electrically connected to the third lower contact electrode 45p via a third contact hole 40CH defined through the first insulating layer 81. The third connecting electrode 40ce is electrically connected to the third pad 40pd via a third through-hole 40ct defined through the second insulating layer 83. The fourth pad 50pd is connected to the first conductivity semiconductor layers 21, 31, 41 of the first, second, and third light-emitting stacks 20, 30, 40 via a first sub-contact hole 50CHa, a second sub-contact hole 50CHb, and a third sub-contact hole 50CHc defined on the first conductivity semiconductor layers 21, 31, 41 of the first, second, and third light-emitting stacks 20, 30, 40. In particular, the first sub-contact hole 50CHa may expose the first upper contact electrode 21n, and the fourth pad 50pd may be connected to the first upper contact electrode 21n via the first sub-contact hole 50CHa. In this manner, the fourth pad 50pd can be electrically connected to the first conductivity type semiconductor layers 21, 31, and 41 via the subcontact holes 50CHa, 50CHb, and 50CHc, thereby simplifying the manufacturing process of the light-emitting element 100. The fourth connecting electrode 50ce is electrically connected to the fourth pad 50pd via the fourth through-hole 50ct defined through the second insulating layer 83.

[0059] In this embodiment, the connecting electrodes 20ce, 30ce, 40ce, and 50ce are shown and described as being in direct contact with each of the pads 20pd, 30pd, 40pd, and 50pd, respectively. However, the connecting electrodes 20ce, 30ce, 40ce, and 50ce are not directly connected to each of the pads 20pd, 30pd, 40pd, and 50pd, and other connectors may be interposed between them.

[0060] The first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd are separated from each other and insulated. According to one embodiment, each of the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd can cover at least a portion of the sides of the first, second, and third light-emitting stacks 20, 30, and 40. Through this, heat generated from the first, second, and third light-emitting stacks 20, 30, and 40 can be easily dissipated.

[0061] According to the illustrated embodiment, each connecting electrode 20ce, 30ce, 40ce, and 50ce may have a substantially elongated shape that protrudes upward from the substrate 11. The connecting electrodes 20ce, 30ce, 40ce, and 50ce may contain, but are not limited to, metals such as Cu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag, or alloys thereof. For example, each of the connecting electrodes 20ce, 30ce, 40ce, and 50ce may contain two or more metals or multiple different metal layers to reduce stress from the elongated shape of each connecting electrode 20ce, 30ce, 40ce, and 50ce. In other embodiments, if the connecting electrodes 20ce, 30ce, 40ce, and 50ce contain Cu, an additional metal may be deposited or plated to suppress oxidation of Cu. In some embodiments, if the connecting electrodes 20ce, 30ce, 40ce, and 50ce contain Cu / Ni / Sn, Cu can prevent Sn from penetrating the light-emitting stack structure. In some embodiments, the connecting electrodes 20ce, 30ce, 40ce, and 50ce may include seed layers for forming a metal layer during the plating process, which will be described later.

[0062] As shown in the drawings, since each of the connection electrodes 20ce, 30ce, 40ce, and 50ce can have a substantially flat upper surface, electrical connection between an external line or electrode described later and the light-emitting stack structure can be easily achieved. According to an embodiment of the present disclosure, the surface area of the light-emitting element 100 is, as known in the art, about 10,000 μm 2 less than, or in other embodiments about 4,000 μm 2 or 2,500 μm 2 When including a micro LED that is less than, the connection electrodes 20ce, 30ce, 40ce, 50ce may overlap at least a part of one of the first, second, and third light-emitting stacks 20, 30, 40, as shown in the drawings. More specifically, each of the connection electrodes 20ce, 30ce, 40ce, and 50ce may overlap at least one step formed on the side surface of the light-emitting stack structure. In this way, since the area of the lower surface of the connection electrode is larger than the area of the upper surface, a larger contact area can be formed between the connection electrodes 20ce, 30ce, 40ce, 50ce and the light-emitting stack structure. As a result, the connection electrodes 20ce, 30ce, 40ce, 50ce can be more stably formed on the light-emitting stack structure. For example, the lengths L1, L2, L3, and L4 of one side surface facing outward of the connection electrodes 20ce, 30ce, 40ce, and 50ce may be different from the lengths L1', L2', L3', and L4' of one side surface facing the center of the light-emitting element 100. More specifically, the length of one side surface of the connection electrode facing outward may be larger than the length of the other side surface facing the center of the light-emitting element 100. For example, the difference between the lengths L and L' of two opposing surfaces may be larger than the thickness (or height) of one of the light-emitting stacks 20, 30, and 40. In such a manner, the structure of the light-emitting element 100 can be strengthened with a larger contact area between the connection electrodes 20ce, 30ce, 40ce, and 50ce and the light-emitting stack structure. Also, since the connection electrodes 20ce, 30ce, 40ce, 50ce can overlap at least one step formed on the side surface of the light-emitting stack structure, the heat generated in the light-emitting stack structure can be more efficiently dissipated to the outside.

[0063] According to an exemplary embodiment, the difference between the length L1, L2, L3, or L4 of one side of the connecting electrode facing outward and the lengths L1', L2', L3', and L4' of the other side facing the center of the light-emitting element 100 may be about 3 μm. In this case, the light-emitting stack structure may be formed thinly. In particular, the first light-emitting stack 20 may have a thickness of about 1 μm, the second light-emitting stack 30 may have a thickness of about 0.7 μm, the third light-emitting stack 40 may have a thickness of about 0.7 μm, and the first and second adhesive layers may each have a thickness of about 0.2 μm to about 0.3 μm, but are not limited thereto. According to another embodiment, the difference between the length L1, L2, L3, or L4 of one side of the connecting electrode facing outward and the lengths L1', L2', L3', and L4' of the other side facing the center of the light-emitting element 100 may be about 10 μm to 16 μm. In this case, the light-emitting stack structure may be formed to have a relatively thicker and more stable structure. In particular, the first light-emitting stack 20 may have a thickness of about 4 μm to about 5 μm, the second light-emitting stack 30 may have a thickness of about 3 μm, the third light-emitting stack 40 may have a thickness of about 3 μm, and the thickness of the first and second adhesive layers may each be about 3 μm, but is not limited thereto. Furthermore, according to other exemplary embodiments, the difference between the length L1, L2, L3 or L4 of one side of the connecting electrode facing outwards and the lengths L1', L2', L3' and L4' of the other side facing the center of the light-emitting element 100 may be about 25% of the longest side length. However, the concept of the present disclosure is not limited to a specific difference in length between the opposing surfaces of the connecting electrodes, and the difference in length between the opposing surfaces of the connecting electrodes may be changed.

[0064] In some exemplary embodiments, at least one of the connecting electrodes 20ce, 30ce, 40ce, and 50ce may be superimposed on the respective sides of each light-emitting stack 20, 30, and 40, thereby allowing the light-emitting stacks 20, 30, and 40 to efficiently dissipate heat generated internally. Furthermore, if the connecting electrodes 20ce, 30ce, 40ce, and 50ce include a reflective material such as metal, they can reflect light emitted from at least one of the light-emitting stacks 20, 30, and 40, thereby improving light efficiency.

[0065] Generally, during manufacturing, an array of multiple light-emitting elements is formed on a substrate. The substrate is cut along scribe lines to individualize (separate) each light-emitting element, and the light-emitting elements can be transferred to another substrate or tape using various transfer techniques for additional processing of the light-emitting elements, such as packaging. In this case, if the light-emitting elements include connecting electrodes such as metal bumps or columns that protrude outward from the light-emitting structure, various problems may occur during subsequent processes, for example, at the transfer stage, due to the structure of the light-emitting elements that exposes each of the connecting electrodes to the outside. Also, depending on the application field, the thickness of the light-emitting elements may be approximately 10,000 μm. 2 Less than approximately 4,000 μm 2 Less than or approximately 2,500 μm 2 When micro-LEDs with a surface area of ​​less than a certain size are included, handling the light-emitting elements can become even more difficult due to their small form factor.

[0066] For example, if the connecting electrode has a substantially long shape, such as a rod, transferring the light-emitting element using conventional vacuum methods becomes difficult because the light-emitting element may not have sufficient suction area due to the protruding structure of the connecting electrode. Also, the exposed connecting electrode may be directly affected by various stresses during subsequent processes, such as when the connecting electrode comes into contact with manufacturing equipment, which can damage the structure of the light-emitting element. As another example, when a light-emitting element is transferred by attaching adhesive tape to the upper surface of the light-emitting element (e.g., the surface facing the substrate), the contact area between the light-emitting element and the adhesive tape may be limited to the upper surface of the connecting electrode. In this case, unlike when the adhesive tape is attached to the lower surface of the light-emitting element (e.g., the substrate), the adhesive force of the light-emitting element to the adhesive tape may be weak, and the light-emitting element may separate from the adhesive tape in an undesirable way during transfer. As yet another example, when transferring a light-emitting element using conventional pick-and-place methods, the ejector pin may directly contact a portion of the light-emitting element positioned between the connecting pins, potentially damaging the superstructure of the light-emitting structure. In particular, the ejection pin may strike the center of the light-emitting element, potentially causing physical damage to the upper light-emitting stack of the light-emitting element.

[0067] According to one embodiment of the present disclosure, the protective layer 90 may be formed on the light-emitting stack structure. More specifically, as shown in Figure 1A, the protective layer 90 is formed between the connecting electrodes 20ce, 30ce, 40ce, and 50ce and can cover at least the sides of the light-emitting stack structure. According to the illustrated embodiment, the protective layer 90 can expose the sides of the substrate 11, the first and second insulating layers 81, 83, and the third light-emitting stack 40. The protective layer 90 may be formed substantially alongside the upper surfaces of the connecting electrodes 20ce, 30ce, 40ce, and 50ce and may contain epoxy molding compound (EMC). This can be formed in a variety of hues, such as black, white, or transparent, but is not limited to the present disclosure. For example, in some embodiments, the protective layer 90 may contain polyimide (PID), in which case the PID may be provided as a non-liquid dry film to increase flatness when applied to the light-emitting stack structure. In some embodiments, the protective layer 90 may contain a photosensitive material. In this manner, the protective layer 90 not only protects the light-emitting structure from external impacts that may be applied during subsequent processes, but also provides a sufficient contact area with the light-emitting element 100 to facilitate handling during subsequent transfer steps. Furthermore, the protective layer 90 can prevent light leakage to the sides of the light-emitting element 100 and prevent, or at least suppress, interference of light emitted from adjacent light-emitting elements 100.

[0068] Figure 2 is a schematic cross-sectional view of a light-emitting stack structure according to one embodiment of the present disclosure. Since the light-emitting stack structure according to the illustrated embodiment is substantially the same as that included in the light-emitting element 100 described above, a description of the configuration that forms substantially the same light-emitting stack structure will be omitted to avoid duplication.

[0069] Referring to Figure 2, the first, second, and third lower contact electrodes 25p, 35p, and 45p in one embodiment of the present disclosure are each connected to the light-emitting signal line S R S G S BThe first conductivity type semiconductor layers 21, 31, and 41 of the first, second, and third light-emitting stacks 20, 30, and 40 may be connected to a common line Sc. The common line Sc may be connected to the first conductivity type semiconductor layer 21 of the first light-emitting stack 20 via a first upper contact electrode 21n.

[0070] One embodiment of the present disclosure allows different voltages to be applied to the first to third light-emitting stacks 20, 30, and 40 by adopting a common structure. For example, the first light-emitting stack 20, which emits red light, can be subjected to a relatively lower voltage than the second and third light-emitting stacks 30 and 40, which emit blue and green light, respectively. Therefore, a voltage source suitable for each light-emitting stack can be used individually, reducing power loss. In the illustrated exemplary embodiment, the light-emitting signal line S R S G S B By using a common line Sc, the first, second, and third light-emitting stacks 20, 30, and 40 can be individually controlled to selectively emit light.

[0071] Figure 2 shows a light-emitting stack structure having a common structure, but the disclosure is not limited thereto. For example, in some exemplary embodiments, the common line Sc is electrically connected to the lower contact electrodes 25p, 35p, and 45p of the first, second, and third light-emitting stacks 20, 30, and 40, respectively, and the light-emitting signal line S R S G S B These may be connected to the first conductivity type semiconductor layers 21, 31, and 41 of the first to third light-emitting stacks 20, 30, and 40, respectively.

[0072] A light-emitting stack structure according to one embodiment of this disclosure can display light of various hues depending on the operating state of each light-emitting stack 20, 30, and 40, whereas conventional light-emitting devices can display various hues by combining a large number of light-emitting cells that emit light of a single hue. More specifically, conventional light-emitting devices generally include light-emitting cells that emit light of different colors, such as red, green, and blue, spaced apart from each other along a two-dimensional plane, in order to realize a full-color display. Thus, conventional light-emitting cells can occupy a relatively large area. However, a light-emitting stack structure according to one embodiment of this disclosure can emit light of different hues by stacking a plurality of light-emitting stacks 20, 30, and 40, providing a high level of integration through a smaller area than conventional light-emitting devices and enabling full color.

[0073] Furthermore, when each light-emitting element 100 is mounted on another substrate to manufacture a display device, for example, the number of each element mounted can be significantly reduced compared to conventional light-emitting elements. In this way, particularly when hundreds of thousands or millions of pixels are formed on a single display device, the manufacturing of display devices using the light-emitting elements 100 can be substantially simplified.

[0074] According to exemplary embodiments, the light-emitting stack structure may further include a variety of additional components to improve the purity and efficiency of the light emitted therefrom. For example, in some exemplary embodiments, wavelength-pass filters may be placed between each light-emitting stack. In some embodiments, irregularities may be formed on the light-emitting surface of at least one light-emitting stack to balance the brightness of the light between each light-emitting stack. For example, it may be necessary to increase the luminosity of green light to bring the RGB luminosity mixing ratio closer to 3:6:1, and for this purpose, irregularities may be formed on the surface of the substrate 11.

[0075] Hereinafter, a method for forming a light-emitting element 100 according to one embodiment of this disclosure will be described with reference to the drawings.

[0076] Figures 3A, 4A, 5A, 6A, 7A, and 8A are plan views showing the process of manufacturing the light-emitting element of Figure 1A according to an exemplary embodiment. Figures 3B, 4B, 5B, 6B, 7B, and 8B are cross-sectional views along the line A-A' of the corresponding plan views shown in Figures 3A, 4A, 5A, 6A, 7A, and 8A according to an exemplary embodiment. Figures 3C, 4C, 5C, 6C, 7C, and 8C are cross-sectional views along the line B-B' of the corresponding plan views shown in Figures 3A, 4A, 5A, 6A, 7A, and 8A according to an exemplary embodiment. Figures 9, 10, 11, 12, and 13 are schematic cross-sectional views showing the manufacturing process of the light-emitting element of Figure 1A according to an exemplary embodiment.

[0077] Referring again to Figure 2, the first conductivity type semiconductor layer 41, the third active layer 43, and the second conductivity type semiconductor layer 45 of the third light-emitting stack 40 can be sequentially grown on the substrate 11 by, for example, a metal-organic chemical vapor deposition (MOCVD) method or a molecular beam epitaxy (MBE) method. The third lower contact electrode 45p may be formed on the third p-type semiconductor layer 45 by, for example, a physical vapor deposition or chemical vapor deposition method, and may contain a transparent conductive oxide (TCO) such as SnO, InO2, ZnO, ITO, or ITZO. When the third light-emitting stack 40 according to one embodiment of the present disclosure emits green light, the substrate 11 may contain Al2O3 (e.g., a sapphire substrate), and the third lower contact electrode 45p may contain a transparent conductive oxide (TCO) such as tin oxide. The first and second light-emitting stacks 20 and 30 can be formed in a similar form by sequentially growing the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer, respectively, on a temporary substrate. The lower contact electrodes containing transparent conductive oxide (TCO) may be formed on the second conductivity type semiconductor layer, for example, by physical vapor deposition or chemical vapor deposition. The first and second light-emitting stacks 20 and 30 are bonded to each other with the first adhesive layer 61 in between, and at least one of the temporary substrates of the first and second light-emitting stacks 20 and 30 can be removed by a laser lift-off process, chemical process, mechanical process, etc. The first and second light-emitting stacks 20 and 30 can then be bonded to the third light-emitting stack 40 with the second adhesive layer 63 in between, and the remaining temporary substrates of the first and second light-emitting stacks 20 and 30 may be removed by a laser lift-off process, chemical process, mechanical process, etc.

[0078] Referring to Figures 3A, 3B, and 3C, various parts of the first, second, and third light-emitting stacks 20, 30, and 40 can be patterned through an etching process or the like to expose the first conductivity semiconductor layer 21, the first lower contact electrode 25p, the first conductivity semiconductor layer 31, the second lower contact electrode 35p, the third lower contact electrode 45p, and the first conductivity semiconductor layer 41. According to the illustrated embodiment, the first light-emitting stack 20 has the smallest area of ​​each of the light-emitting stacks 20, 30, and 40. On the other hand, the third light-emitting stack 40 can have the largest area of ​​each of the light-emitting stacks 20, 30, and 40, and as a result, the luminosity of the third light-emitting stack 40 can be relatively increased. However, the concept of this disclosure is not particularly limited to the relative sizes of the light-emitting stacks 20, 30, and 40.

[0079] Referring to Figures 4A, 4B, and 4C, a portion of the upper surface of the first conductivity type semiconductor layer 21 of the first light-emitting stack 20 may be patterned through wet etching to form the first upper contact electrode 21n. As described above, the first upper contact electrode 21n is formed in a recessed region of the first conductivity type semiconductor layer 21 with a thickness of about 100 nm, which can improve, for example, ohmic contact between them.

[0080] Referring to Figures 5A, 5B, and 5C, the first insulating layer 81 may be formed to cover the light-emitting stacks 20, 30, and 40, and a portion of the first insulating layer 81 may be removed to form the first, second, third, and fourth contact holes 20CH, 30CH, 40CH, and 50CH. The first contact hole 20CH is defined on the first lower contact electrode 25p and exposes a portion of the first lower contact electrode 25p. The second contact hole 30CH is defined on the second lower contact electrode 35p and can expose a portion of the second lower contact electrode 35p. The third contact hole 40CH is defined on the third lower contact electrode 45p and can expose a portion of the third lower contact electrode 45p.

[0081] The fourth contact hole 50CH provides a passage for allowing electrical connection to the first conductivity type semiconductor layers 21, 31, 41 of the first to third light-emitting stacks 20, 30, 40. The fourth contact hole 50CH may include a first subcontact hole 50CHa, a second subcontact hole 50CHb, and a third subcontact hole 50CHc. The first subcontact hole 50CHa is defined on the first conductivity type semiconductor layer 21 and can expose a portion of the first upper contact electrode 21n; the second subcontact hole 50CHb is defined on the first conductivity type semiconductor layer 31 and can expose a portion of the first conductivity type semiconductor layer 31; and the third subcontact hole 50CHc is defined on the first conductivity type semiconductor layer 41 and can expose a portion of the first conductivity type semiconductor layer 41.

[0082] Referring to Figures 6A, 6B, and 6C, the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd are formed on a first insulating layer 81 which is formed to have first, second, third, and fourth contact holes 20CH, 30CH, 40CH, and 50CH. The first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd can be formed, for example, by forming a conductive layer substantially over the entire surface of the substrate 11 and patterning the conductive layer using a photolithography process.

[0083] The first pad 20pd is formed to overlap with the region where the first contact hole 20CH is formed and may be connected to the first lower contact electrode 25p via the first contact hole 20CH. The second pad 30pd is formed to overlap with the region where the second contact hole 30CH is formed and may be connected to the second lower contact electrode 35p via the second contact hole 30CH. The third pad 40pd is formed to overlap with the region where the third contact hole 40CH is formed and may be connected to the third lower contact electrode 45p via the third contact hole 40CH. The fourth pad 50pd is formed to overlap with the region where the fourth contact hole 50CH is formed, in particular the region where the first, second and third sub-contact holes 50CHa, 50CHb, and 50CHc are formed and may be electrically connected to the first conductivity type semiconductor layers 21, 31, and 41 of the first to third light-emitting stacks 20, 30, and 40.

[0084] Referring to Figures 7A, 7B, and 7C, the second insulating layer 83 may be formed on the first insulating layer 81. The second insulating layer 83 may contain silicon oxide and / or silicon nitride. However, the disclosure is not limited thereto, and in some embodiments, the first and second insulating layers 81 and 83 may contain inorganic materials. Subsequently, the second insulating layer 83 may be patterned to form first, second, third, and fourth through-holes 20ct, 30ct, 40ct, and 50ct that expose first to fourth pads 20pd, 30pd, 40pd, and 50pd.

[0085] A first through-hole 20ct formed on the first pad 20pd exposes a portion of the first pad 20pd. A second through-hole 30ct formed on the second pad 30pd exposes a portion of the second pad 30pd. A third through-hole 40ct formed on the third pad 40pd exposes a portion of the third pad 40pd. A fourth through-hole 50ct formed on the fourth pad 50pd exposes a portion of the fourth pad 50pd. In the illustrated exemplary embodiment, the first, second, third, and fourth through-holes 20ct, 30ct, 40ct, and 50ct can be defined within the regions where the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd are formed.

[0086] Referring to Figures 8A, 8B, and 8C, first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce are formed on the second insulating layer 83, which has first, second, third, and fourth through-holes 20ct, 30ct, 40ct, and 50ct formed thereon. The first connecting electrode 20ce may be formed to overlap with the region where the first through-hole 20ct is formed and connected to the first pad 20pd via the first through-hole 20ct. The second connecting electrode 30ce may be formed to overlap with the region where the second through-hole 30ct is formed and connected to the second pad 30pd via the second through-hole 30ct. The third connecting electrode 40ce may be formed to overlap with the region where the third through-hole 40ct is formed and connected to the third pad 40pd via the third through-hole 40ct. The fourth connecting electrode 50ce may be formed to overlap with the region in which the fourth through-hole 50ct is formed, and may be connected to the fourth pad 50pd via the fourth through-hole 50ct.

[0087] The first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce may be formed on the light-emitting stack structure spaced apart from each other. The first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce are electrically connected to the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd, respectively, and can transmit external signals to the respective light-emitting stacks 20, 30, and 40.

[0088] The method for forming the first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce is not particularly limited. For example, according to one embodiment of the present disclosure, a seed layer may be deposited on the light-emitting stack structure as a conductive surface, and a photoresist pattern may be formed such that the seed layer is exposed at the positions where the connecting electrodes are formed. According to one embodiment, the seed layer may be deposited to a thickness of about 1000 Å, but is not limited thereto. Subsequently, the seed layer may be plated with a metal such as Cu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag or an alloy thereof, and the photoresist pattern and seed layer remaining between each connecting electrode may be removed. In some exemplary embodiments, an additional metal may be deposited or plated on the plated metal (e.g., each connecting electrode) by electroless nickel immersion gold (ENIG) or the like to prevent or at least suppress oxidation of the plated metal. In some embodiments, the seed layer may remain on each connecting electrode.

[0089] According to the illustrated exemplary embodiments, each of the connecting electrodes 20ce, 30ce, 40ce, and 50ce may have a substantially elongated shape that is away from the substrate 11. In other exemplary embodiments, the connecting electrodes 20ce, 30ce, and 40ce may include two or more metals or multiple different metal layers to reduce stress from the elongated shape of the connecting electrodes 20ce, 30ce, 40ce, and 50ce. However, the present disclosure is not limited to the specific shapes of the connecting electrodes 20ce, 30ce, 40ce, and 50ce, and in some embodiments, the connecting electrodes can have a variety of shapes.

[0090] As shown in the drawings, each of the connecting electrodes 20ce, 30ce, 40ce, and 50ce may have a substantially flat upper surface to facilitate electrical connection between the light-emitting stack structure and the external line or electrode. Each connecting electrode 20ce, 30ce, 40ce, and 50ce may overlap with at least one step formed on the side of the light-emitting stack structure. In this manner, the lower surface of the connecting electrode may have a greater width than the upper surface, providing a larger contact area between the connecting electrodes 20ce, 30ce, 40ce, and 50ce and the light-emitting stack structure, resulting in a more stable structure in which the light-emitting element 100 can withstand various subsequent processes together with the protective layer 90. In this case, the lengths L1 to L4 of one side of the connecting electrodes 20ce, 30ce, 40ce, and 50ce facing outwards and the lengths L1' to L4' of the other surface facing the center of the light-emitting element 100 may differ from each other. For example, the difference in length between two opposing surfaces of the connecting electrode may be, but is not limited to, 3 μm to 16 μm.

[0091] A protective layer 90 is then positioned between the connecting electrodes 20ce, 30ce, 40ce, and 50ce. The protective layer 90 may be formed substantially adjacent to the upper surfaces of the connecting electrodes 20ce, 30ce, 40ce, and 50ce by a polishing process or the like. In one embodiment, the protective layer 90 may, but is not limited to, a black epoxy molding compound (EMC). For example, in some embodiments, the protective layer 90 may include a photosensitive polyimide dry film (PID). In this manner, the protective layer 90 not only protects the light-emitting structure from external impacts that may be applied during subsequent processes, but also provides sufficient contact area to the light-emitting element 100 to facilitate handling during subsequent transfer steps. Furthermore, the protective layer 90 can prevent light leakage to the sides of the light-emitting element 100 and prevent, or at least suppress, interference of light emitted from adjacent light-emitting elements 100.

[0092] Figure 9 illustrates a plurality of light-emitting elements 100 arranged on a substrate 11, each light-emitting element 100 undergoing a unification process to separate them. Referring to Figure 10, according to one embodiment of the present disclosure, each laser beam can be irradiated between the light-emitting stack structures to form separation paths that partially separate each light-emitting stack structure. Referring to Figure 11, separation paths may be added within the substrate 11 using a stealth laser. The stealth laser may be irradiated from a direction opposite to the laser irradiation surface in Figure 10.

[0093] Referring to Figure 12, the substrate 11 can be cut or broken using a variety of methods known in the art to unify each light-emitting element 100 while it is attached to the first bonding layer 95. For example, the substrate 11 can be cut by dicing it through scribe lines formed thereon, or it can be broken by applying mechanical force along separation paths formed during the laser irradiation process, for example. The first bonding layer 95 may be a tape, but the disclosure is not limited thereto, as long as the first bonding layer 95 can separate the light-emitting elements 100 while stably attaching them in subsequent steps. Although it has been described that the first bonding layer 95 is attached to the substrate 11 after the laser irradiation step, in some exemplary embodiments the first bonding layer 95 may be attached to the substrate 11 before the laser irradiation step.

[0094] Referring to Figure 13, after the substrate 11 is separated into individual light-emitting elements 100, the first bonding layer 95 may be expanded, and as a result, each light-emitting element 100 may be spatially separated from one another.

[0095] Figures 14, 15, and 16 are schematic cross-sectional views illustrating a manufacturing process for a light-emitting package according to one embodiment of the present disclosure. The light-emitting element 100 according to one embodiment of the present disclosure can be transferred and packaged in a variety of methods known in the art. Hereinafter, the transfer of the light-emitting element 100 by attaching a second adhesive layer 13 to a substrate 11 using a carrier substrate 11c will be described exemplarily, but the present disclosure is not limited to any particular transfer method.

[0096] Referring to Figure 14, according to one embodiment of the present disclosure, the unified light-emitting element 100 may be transferred and arranged on the carrier substrate 11c with a second adhesive layer 13 in between. In this case, if the light-emitting element includes connecting electrodes that protrude outward from the light-emitting stack structure, as described above, the non-uniform structure may cause various problems in subsequent processes, particularly the transfer process. Also, depending on the application field, the light-emitting element may be approximately 10,000 μm 2 Less than approximately 4,000 μm 2 Less than or approximately 2,500 μm 2 When micro-LEDs with a surface area of ​​less than 50°C are included, the small form factor can make handling the light-emitting elements even more difficult. However, providing a light-emitting element 100 in an exemplary embodiment in which a protective layer 90 is placed between each connecting electrode 20ce, 30ce, 40ce, 50ce not only facilitates handling of the light-emitting element 100 during subsequent processes such as transfer and packaging, but also protects the light-emitting structure from external impacts and prevents light interference between adjacent light-emitting elements 100.

[0097] The carrier substrate 11c is not particularly limited, as long as it stably mounts the light-emitting element 100 onto the second adhesive layer 13. The second adhesive layer 13 may be a tape, but the disclosure is not limited to this, as long as the second adhesive layer 13 stably adheres the light-emitting element 100 to the carrier substrate 11c and allows the light-emitting element 100 to be separated during subsequent processes. In some embodiments, the light-emitting element 100 in Figure 13 may not be transferred to a separate carrier substrate 11c, but may be transferred directly to the circuit board 11p.

[0098] The light-emitting element 100 may be mounted on a circuit board 11p. According to one embodiment, the circuit board 11p may include an upper circuit electrode 11pa, a lower circuit electrode 11pc, and an intermediate circuit electrode 11pb that are electrically connected to each other. Each upper circuit electrode 11pa may correspond to the first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce, respectively. In an exemplary embodiment, each upper circuit electrode 11pa is surface-treated with ENIG and partially melted at a high temperature to facilitate electrical connection to each connecting electrode of the light-emitting element 100.

[0099] According to the illustrated embodiment, the light-emitting elements 100 can be spaced apart from each other on the carrier substrate 11c at a desired pitch, taking into consideration the pitch P of the upper circuit electrodes of the circuit board 11p which will be mounted on the final target device such as a display device (see Figure 16B).

[0100] According to one embodiment of the present disclosure, the first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce of the light-emitting element 100 may be bonded to the upper circuit electrode 11pa of the circuit board 11p, for example, by anisotropic conductive film (ACF) bonding. When the light-emitting element 100 is bonded to the circuit board through ACF bonding, which can be performed at a lower temperature than other bonding methods, it is possible to prevent the light-emitting element 100 from being exposed to high temperatures during bonding. However, the present disclosure is not limited to a specific bonding method. For example, in some exemplary embodiments, each light-emitting element 100 may be bonded to the circuit board 11p using anisotropic conductive paste (ACP), solder, a ball grid array (BGA), or microbumps containing at least one of Cu and Sn. In this case, the upper surfaces of the connecting electrodes 20ce, 30ce, 40ce, and 50ce and the protective layer 90 are substantially aligned with each other by a polishing process or the like, which increases the adhesion of the light-emitting element 100 to the anisotropic conductive film and allows for the formation of a more stable structure when bonded to the circuit board 11p.

[0101] Referring to Figure 15, a molding layer 91 is formed between each light-emitting element 100. According to one embodiment, the molding layer 91 can block light by reflecting or absorbing the light emitted from the light-emitting elements 100. The molding layer 91 may, in particular, be aligned with the top surface of the light-emitting elements 100, i.e., the light-emitting surface, thereby narrowing the viewing angle of the light emitted from the first to third light-emitting stacks 20, 30, and 40. For example, the molding layer 91 may cover the side surface of the substrate 11 and be aligned with the top surface of the substrate 11. Thus, the molding layer 91 can prevent light from being emitted to the side surface of the substrate 11 and narrow the viewing angle. Furthermore, since the light-emitting surface is limited to the top surface of the substrate 11, the viewing angles of the light from the first to third light-emitting stacks 20, 30, and 40 become substantially the same. In addition, the molding layer 91, together with the protective layer 90 formed on the light-emitting elements 100, provides additional protection to the light-emitting package by reinforcing its structure. By placing a molding layer 91 between each adjacent light-emitting element 100, protective layers 90 are placed on both sides of the molding layer 91 between each adjacent connecting electrode.

[0102] In exemplary embodiments, the molding layer 91 may contain an organic or inorganic polymer. In some embodiments, the molding layer 91 may further contain a filler such as silica or alumina. In exemplary embodiments, the molding layer 91 may contain the same material as the protective layer 90. The molding layer 91 can be formed by a variety of methods known in the art, such as lamination, plating and / or printing methods. For example, the molding layer 91 may be formed by a vacuum lamination process in which an organic polymer sheet is placed on the light-emitting element 100 and high temperature and pressure are applied in a vacuum, thereby improving light uniformity by providing a substantially flat top surface of the light-emitting package. The molding layer 91 may be partially removed by a grinding process or a full-surface etching process so that the top surface of the light-emitting element 100 is exposed.

[0103] In some embodiments, the substrate 11 may be removed from the light-emitting element 100 before the molding layer 91 is formed. In this case, the molding layer 91 can cover the sides of the first conductivity type semiconductor layer 41, exposing the upper surface of the first conductivity type semiconductor layer 41.

[0104] Referring to Figures 16A and 16B, the light-emitting elements 100 arranged on the circuit board 11p may be formed as a light-emitting package 110 by cutting them in a desired configuration. Figure 16B includes four light-emitting elements 100 (2×2) arranged on the circuit board 11p. However, the disclosure is not limited to a specific number of light-emitting elements formed in the light-emitting package 110. For example, in some embodiments, the light-emitting package 110 may include one or more light-emitting elements 100 formed on the circuit board 11p. Furthermore, the disclosure is not limited to a specific arrangement of one or more light-emitting elements 100 within the light-emitting package 110; for example, one or more light-emitting elements 100 within the light-emitting package 110 may be arranged in an n×m array, where n and m are natural numbers. According to one embodiment, the circuit board 11p may include scan lines and data lines for independently driving each of the light-emitting elements 100 contained in the light-emitting package 110.

[0105] Figure 17 is a schematic cross-sectional view illustrating a display device according to one embodiment of the present invention.

[0106] Referring to Figure 17, the display device may include a display substrate 11b and a light-emitting package 110. The light-emitting package 110 may be mounted on the display substrate 11b of a final device such as a display device. The display substrate 11b may include target electrodes 11s corresponding to the lower circuit electrodes 11pc of the light-emitting package 110. The display device according to one embodiment of the present disclosure may include a plurality of pixels, and each light-emitting element 100 may be arranged corresponding to each pixel. More specifically, each light-emitting stack of the light-emitting element 100 according to one embodiment of the present disclosure may correspond to each subpixel of a single pixel. Since the light-emitting element 100 includes vertically stacked light-emitting stacks 20, 30 and 40, the number of elements transferred to each subpixel can be substantially reduced compared to the number of conventional light-emitting elements. Furthermore, since the lengths of the opposing surfaces of the connecting electrodes are different from each other, the connecting electrodes can be stably formed on the light-emitting stack structure, and the internal structure can be strengthened. In addition, the light-emitting element 100 according to some embodiments includes a protective layer 90 between each connecting electrode, so that the light-emitting element 100 can be protected from external impacts.

[0107] In this embodiment, the light-emitting package 110 is described as being mounted on the display substrate 11b, but the process of manufacturing the light-emitting package 110 can be omitted, and the molding layer 91 can be formed by directly mounting the light-emitting element 100 on the display substrate 11b.

[0108] Figure 18 is a schematic cross-sectional view illustrating a light-emitting package according to another embodiment of the present disclosure.

[0109] Referring to Figure 18, the light-emitting package according to this embodiment is substantially similar to the light-emitting packages already described with reference to Figures 15, 16A, and 16B, but differs in that the light-emitting element 200 does not include the substrate 11. The substrate 11 is removed from the light-emitting element 100, and thus the first conductivity type semiconductor layer 41 is exposed. The light-emitting element 200 emits light through the upper surface of the first conductivity type semiconductor layer 41, and thus the upper surface of the first conductivity type semiconductor layer 41 becomes the light-emitting surface. The molding layer 91 covers the side surface of the first conductivity type semiconductor layer 41, exposing its upper surface.

[0110] Figure 19A is a graph showing the viewing angle of the light-emitting element 100 when a conventional molding layer is not used, Figure 19B is a graph showing the viewing angle of the light-emitting element 100 when a transparent molding layer according to one embodiment of the present disclosure is used, and Figure 19C is a graph showing the viewing angle of the light-emitting element 100 when a black molding layer according to one embodiment of the present disclosure is used.

[0111] Referring to Figure 19A, when the molding layer 91 is not used, the viewing angles of the red light R, green light G, and blue light B emitted from the light-emitting element 100 differ significantly from each other. In particular, the viewing angle of the green light G emitted from the third light-emitting stack 40, which is closer to the light-emitting surface, is the largest. Specifically, the viewing angle of the red light R was approximately 125.7 degrees, the viewing angle of the blue light B was approximately 128.8 degrees, and the viewing angle of the green light G was approximately 155.6 degrees. The viewing angle of the green light G was approximately 30 degrees larger than that of the red light R and blue light B.

[0112] Referring to Figure 19B, it can be confirmed that even when the transparent molding layer 91 is adopted, the viewing angles of all light sources—red light R, green light G, and blue light B—decrease compared to the viewing angles in Figure 19A. Furthermore, it can be confirmed that the difference in viewing angles between red light R, green light G, and blue light B decreases as the viewing angle of green light G decreases even more significantly. Specifically, the viewing angle of red light R was approximately 128.3 degrees, the viewing angle of blue light B was approximately 126.4 degrees, and the viewing angle of green light G was approximately 135.2 degrees. The viewing angle of green light G did not exceed approximately 10 degrees compared to the viewing angles of red light R and blue light B.

[0113] Referring to Figure 19C, it can be confirmed that when the black molding layer 91 is used, the viewing angles of all light sources—red light R, green light G, and blue light B—are further reduced compared to Figure 19B. Furthermore, it can be confirmed that the difference in viewing angles between red light R, green light G, and blue light B is also further reduced. Specifically, the viewing angle of red light R was approximately 124.2 degrees, the viewing angle of blue light B was approximately 119.0 degrees, and the viewing angle of green light G was approximately 126.5 degrees. The viewing angle of green light G did not exceed approximately 10 degrees compared to the viewing angles of red light R and blue light B.

[0114] While specific exemplary embodiments and practices have been described herein, other embodiments and modifications will be apparent from this description. Therefore, this disclosure is not limited to such embodiments and includes a broader range of the appended claims and a variety of modifications and equivalent configurations that will be apparent to those skilled in the art.

Claims

1. circuit board and A plurality of light-emitting elements disposed on the substrate, each light-emitting element comprising a connecting electrode disposed between the light-emitting element and the substrate, and a protective layer disposed on the substrate, The system comprises a molding layer that surrounds the sides of the plurality of light-emitting elements and exposes their upper surfaces, The area of ​​the upper surface of the connecting electrode is larger than the area of ​​the lower surface of the connecting electrode. The protective layer covers the side surface of the connecting electrode between the upper surface and the lower surface. The upper surface of the connecting electrode includes at least one step, The molding layer is configured to reflect or absorb light emitted from the light-emitting element, Each of the plurality of light-emitting elements includes a first LED that emits red light, a second LED that emits green light, and a third LED that emits blue light. A light-emitting module in which the difference between the viewing angle of the green light and the viewing angle of the red light or the blue light is less than 10 degrees.

2. The light-emitting module according to claim 1, wherein each light-emitting element includes a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer.

3. The light-emitting module according to claim 2, further comprising a bonding layer interposed between the light-emitting element and the substrate.

4. The aforementioned connecting electrode is A first connecting electrode electrically connected to the first conductivity type semiconductor layer, The light-emitting module according to claim 3, further comprising a second connecting electrode electrically connected to the second conductive semiconductor layer.

5. The light-emitting module according to claim 1, wherein the difference in length between the two opposing sides of the connecting electrode is 3 μm to 16 μm.

6. The light-emitting module according to claim 1, wherein the molding layer is made of a polymer material.

7. The light-emitting module according to claim 2, wherein the light emitted from each light-emitting element is reflected by a reflecting portion arranged between the light-emitting element and the connecting electrode, and the reflecting portion has a multilayer structure formed of two or more insulating layers having different refractive indices.

8. The light-emitting module according to claim 1, wherein the lower surface of the connecting electrode is substantially aligned with the lower surface of the protective layer.

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