LED DISPLAY DEVICE.

Abstract

A display device according to one embodiment comprises: a display substrate; a plurality of light-emitting elements arranged on the display substrate; light barrier layers arranged between each pair of light-emitting elements; and a transparent layer covering the light-emitting elements and the light barrier layers, wherein each of the light-emitting elements comprises: 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 disposed closer to the upper surface of the light-emitting element than the first LED subunit.

Description

LED DISPLAY DEVICE TECHNICAL FIELD Exemplary embodiments of the invention relate generally to a display apparatus, and, more particularly, to an LED display apparatus. STATE OF THE ART As an inorganic light source, light-emitting diodes have been used in various technical fields, such as displays, vehicle lamps, general lighting, and the like. With several advantages of light-emitting diodes over conventional light sources, such as longer lifespan, lower power consumption, and rapid response, light-emitting diodes have been replacing conventional light sources. Light-emitting diodes have been used as backlighting light sources in display devices. However, LED displays that directly display images using light-emitting diodes have recently been developed. Generally, a display device realizes various colors by mixing blue, green, and red light. To display various images, the display device includes a plurality of pixels, each of which has subpixels corresponding to blue, green, and red light, respectively. In this way, the color of a given pixel is determined based on the colors of the subpixels, so that images can be displayed by combining these pixels. Since LEDs can emit various colors depending on their materials, a display device can be created by arranging individual LED chips emitting blue, green, and red light in a two-dimensional plane. However, when an LED chip is placed in each subpixel, the number of LED chips can increase, which can require excessive assembly time during manufacturing. Since the subpixels are arranged in the two-dimensional plane of the display device, a pixel that includes the subpixels for blue, green, and red light occupies a relatively large area. Therefore, it may be necessary to reduce the area of ​​each LED chip to arrange the subpixels in a restricted area. However, reducing the size of the LED chips can cause difficulties in mounting the LED chips and reduce the luminous areas of the LED chips. Meanwhile, a display that produces multiple colors needs to consistently provide high-quality white light. Conventional televisions use a 3:6:1 RGB mixing ratio to produce standard D65 white light. Specifically, the luminous intensity of red is higher than that of blue, and that of green is relatively the highest. However, since conventional LED chips have a relatively high luminous intensity of the blue LED compared to other LEDs, it is difficult to match the RGB mixing ratio in displays that use LED chips. Furthermore, when the viewing angles of the blue, green, and red light emitted from a pixel are large, light interference between adjacent pixels can occur, making it difficult to achieve clear image quality. However, when the viewing angle of the light emitted from a pixel is narrow, light variation is likely to occur due to a difference in light intensities between pixels. Therefore, it may be necessary to adjust the viewing angle of the light emitted from the pixel to an appropriate level. DIVULGATION Technical problem Display apparatus constructed in accordance with exemplary embodiments of the invention are capable of magnifying an area of ​​each sub-pixel in a restricted pixel area. Exemplary embodiments also provide a display apparatus that is capable of reducing a time associated with an assembly process. Exemplary embodiments further provide a display apparatus that is capable of easily controlling an RGB mixing ratio. Exemplary embodiments further provide a display apparatus in which the viewing angles of various colors of light emitted within a pixel are adjusted to an appropriate level. Technical solution A display apparatus according to an exemplary embodiment includes a display substrate, a plurality of light-emitting devices disposed on the display substrate, a light-blocking layer disposed between the light-emitting devices, and a transparent layer covering the light-emitting devices and the light-blocking layer, wherein at least one of the light-emitting devices includes a first LED subunit, a second LED subunit disposed above the first LED subunit, and a third LED subunit disposed above the second LED subunit, and the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit. A display apparatus according to another exemplary embodiment includes a display substrate, a plurality of light-emitting devices disposed on the display substrate, a black molding layer disposed between the light-emitting devices to block light emitted from the light-emitting devices, and a transparent layer that at least partially covers the light-emitting devices and is configured to transmit light emitted from the light-emitting devices, wherein at least one of the light-emitting devices includes a first LED subunit, a second LED subunit disposed above the first LED subunit, and a third LED subunit disposed above the second LED subunit, and the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit. Description of the drawings FIG. 1A is a schematic perspective view of a light emitting device according to an exemplary embodiment. FIG. 1B is a schematic plan view of the light emitting device of FIG. 1A. FIG. 1C and FIG. 1D are schematic cross-sectional views taken along lines AA' and BB' of FIG. 1B, respectively. FIG. 2 is a schematic cross-sectional view of a light-emitting stack structure according to an exemplary embodiment. FIGS. 3A, 4A, 5A, 6A, 7A and 8A are plan views illustrating a manufacturing process of the light emitting device of FIG. 1A according to an exemplary embodiment. FIGS. 3B, 4B, 5B, 6B, 7B and 8B are cross-sectional views taken along line AA' of the corresponding plan views shown in FIGS. 3A, 4A, 5A, 6A, 7A and 8A in accordance with an exemplary embodiment. FIGS. 3C, 4C, 5C, 6C, 7C and 8C are cross-sectional views taken along line BB' of the corresponding plan views shown in FIGS. 3A, 4A, 5A, 6A, 7A and 8A according to an exemplary embodiment. FIGS. 9, 10, 11, 12, and 13 are cross-sectional views schematically showing a manufacturing process of the light-emitting device of FIG. 1A according to an exemplary embodiment. FIGS. 14, 15 and 16 are cross-sectional views schematically illustrating a manufacturing process of a light-emitting package according to an exemplary embodiment. FIG. 17 is a schematic cross-sectional view illustrating a display apparatus according to an exemplary embodiment. FIG. 18 is a schematic cross-sectional view illustrating a light emitting package according to another exemplary embodiment. FIG. 19 is a schematic cross-sectional view illustrating a light emitting package according to another exemplary embodiment. FIG. 20 is a schematic cross-sectional view illustrating a light emitting package according to another exemplary embodiment. FIG. 21 is a schematic plan view illustrating a light emitting package according to another exemplary embodiment. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example to fully convey the spirit of the present disclosure to those skilled in the art to which the present disclosure pertains. Accordingly, the present disclosure is not limited to the embodiments disclosed herein and may also be implemented in different forms. In the drawings, the widths, lengths, thicknesses, and the like of the devices may be exaggerated for clarity and descriptive purposes. When an element or layer is referred to as being arranged above or disposed upon another element or layer, it may be directly arranged above or disposed upon the other element or layer, or intervening devices or layers may be present. Throughout the specification, like reference numerals denote similar devices having the same or similar functions. A display apparatus according to an exemplary embodiment includes a display substrate, a plurality of light-emitting devices arranged on the display substrate, a light-blocking layer disposed between the light-emitting devices, and a transparent layer covering the light-emitting devices and the light-blocking layer, wherein at least one of the light-emitting devices includes a first LED subunit, a second LED subunit disposed above the first LED subunit, and a third LED subunit disposed above the second LED subunit, and the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit. According to exemplary embodiments, since the first, second, and third LED subunits overlap each other, an area of ​​each subpixel within a restricted pixel area can be increased without increasing the pixel area. Furthermore, since the light-emitting device includes the first, second, and third LED subunits, the number of light-emitting devices can be reduced compared to conventional light-emitting devices, and, consequently, a time associated with an assembly process of the light-emitting devices can be reduced. Furthermore, since the light-blocking layer is disposed between the light-emitting devices, light interference between the light-emitting devices can be prevented, and since the transparent layer covers the light-emitting devices, the viewing angles of the light emitted from the light-emitting device can be increased. The light-blocking layer may be configured to block light by absorbing light emitted by the light-emitting device, and the transparent layer may be configured to transmit light emitted by the light-emitting device. The light blocking layer may include a black molding layer. The first, second, and third LED subunits may be configured to emit red light, blue light, and green light, respectively. By setting the second LED subunit to emit blue light and the third LED subunit to emit green light, the luminous intensity of the blue light can be reduced and the luminous intensity of the green light can be increased to control an RGB color mixing ratio. However, the inventive concept is not limited thereto, and the first, second, and third LED subunits may be configured to emit red light, green light, and blue light, respectively. The first LED subunit may include a first light-emitting stack, the second LED subunit may include a second light-emitting stack, the third LED subunit may include a third light-emitting stack, and each of the light-emitting stacks may include a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer. The transparent layer may partially cover the light-emitting devices. The transparent layer can be arranged to cross the light-emitting devices in one direction. Thus, the viewing angles of the light emitted from the light-emitting devices can be adjusted differently depending on their directions. The transparent layer may have a mesh shape and may include a first transparent layer extending in a lateral direction and a second transparent layer extending in a longitudinal direction, the first transparent layer may cross the light-emitting devices, and the second transparent layer may be disposed over the light-blocking layer in a region between the light-emitting devices. An upper surface of the light-blocking layer may be positioned at the same elevation or lower than that of the light-emitting device. The light-emitting device may further include a substrate disposed on the third LED subunit, and a refractive index difference between the transparent layer and air may be smaller than a refractive index difference between the substrate and the first conductive-type semiconductor of the third light-emitting stack. The light-emitting device may further include a substrate disposed over the third LED subunit, and the upper surface of the light-blocking layer may be positioned at a lower elevation than an upper surface of the substrate to expose at least a portion of a side surface of the substrate. The light-blocking layer may be positioned at a lower elevation than an upper surface of the third light-emitting stack to expose at least a portion of a side surface of the third light-emitting stack. The light emitting device 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. The light emitting device may further include a first connection electrode electrically connected to the first LED subunit, a second connection electrode electrically connected to the second LED subunit, a third connection electrode electrically connected to the third LED subunit, and a fourth connection electrode commonly electrically connected to the first, second, and third subunits. The display apparatus may further include a circuit board interposed between the display substrate and the light-emitting device, wherein the first, second, third, and fourth connection electrodes may be bonded to the circuit board, and the light-blocking layer may be disposed on the circuit board. The first connection electrode, the second connection electrode, and the third connection electrode may be electrically connected to the second conductive semiconductor layers of the first light-emitting cell, the second light-emitting cell, and the third light-emitting cell, respectively, and the fourth connection electrode may be commonly electrically connected to the first conductive semiconductor layers of the first, second, and third light-emitting cells. The light emitting device may further include first, second, and third lower contact electrodes that contact the second conductive semiconductor layers of the first, second, and third light emitting cells, respectively, and a first insulating layer having first, second, and third contact holes that partially expose the first, second, and third lower contact electrodes, the first insulating layer may have sub-contact holes disposed in the first conductive semiconductor layers of the first, second, and third light emitting cells, and the sub-contact holes may be spaced apart from each other. The light emitting device may further include first, second, and third pads superimposed with the first, second, and third contact holes and a fourth pad superimposed with the sub-contact holes, and the first, second, third, and fourth connection electrodes may be electrically connected to the first, second, third, and fourth pads, respectively. A display apparatus according to another exemplary embodiment includes a display substrate, a plurality of light-emitting devices disposed on the display substrate, a black molding layer disposed between the light-emitting devices to block light emitted from the light-emitting devices, and a transparent layer that at least partially covers the light-emitting devices and is configured to transmit light emitted from the light-emitting devices, wherein at least one of the light-emitting devices includes a first LED subunit, a second LED subunit disposed above the first LED subunit, and a third LED subunit disposed above the second LED subunit, and the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit. An upper surface of the black molding layer may be positioned at the same elevation or lower than that of the light-emitting devices. Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. As used herein, a light-emitting stack structure, a light-emitting device, or a light-emitting package may include micro-LEDs, having a light-emitting area of ​​10,000 pm2 or less, as is well known in the art. In other exemplary embodiments, the micro-LED may have a light-emitting area of ​​4,000 pm2 or less, and, furthermore, 2,500 pm2 or less. FIG. 1A is a schematic perspective view of a light emitting device according to an exemplary embodiment, FIG. 1B is a schematic plan view of the light emitting device of FIG. 1A, and FIG. 1C and FIG. 1D are schematic cross-sectional views taken along lines AA' and BB' of FIG. 1B, respectively. Referring to FIGS. 1A and 1B, a light-emitting device 100 includes a light-emitting stack structure, a first connecting electrode 20ce, a second connecting electrode 30ce, a third connecting electrode 40ce, and a fourth connecting electrode 50ce formed in the light-emitting stack structure, and a protective layer 90 surrounding the connecting electrodes 20ce, 30ce, 40ce, and 50ce. An array of light-emitting devices 100 may be formed on a substrate 11, and the light-emitting device 100 illustrated in FIG. 1A shows the singulation of the array, and thus may be referred to as a light-emitting device. The configuration and singulation of the light-emitting devices 100 will be described in more detail later.In some exemplary embodiments, the light-emitting device 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 more detail below. The first connection electrode, the second connection electrode, and the third connection electrode may be electrically connected to the second conductive semiconductor layers of the first light-emitting cell, the second light-emitting cell, and the third light-emitting cell, respectively, and the fourth connection electrode may be commonly electrically connected to the first conductive semiconductor layers of the first, second, and third light-emitting cells. The light emitting device may further include first, second, and third bottom contact electrodes that contact the second conductive semiconductor layers of the first, second, and third light emitting cells, respectively, and a first insulating layer having first, second, and third contact holes that partially expose the first, second, and third bottom contact electrodes, the first insulating layer may have sub-contact holes disposed in the first conductive semiconductor layers of the first, second, and third light emitting cells, and the sub-contact holes may be spaced apart from each other. The light emitting device may further include first, second, and third pads superimposed with the first, second, and third contact holes and a fourth pad superimposed with the sub-contact holes, and the first, second, third, and fourth connection electrodes may be electrically connected to the first, second, third, and fourth pads, respectively. A display apparatus according to another exemplary embodiment includes a display substrate, a plurality of light-emitting devices disposed on the display substrate, a black molding layer disposed between the light-emitting devices to block light emitted from the light-emitting devices, and a transparent layer that at least partially covers the light-emitting devices and is configured to transmit light emitted from the light-emitting devices, wherein at least one of the light-emitting devices includes a first LED subunit, a second LED subunit disposed above the first LED subunit, and a third LED subunit disposed above the second LED subunit, and the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit. An upper surface of the black molding layer may be positioned at the same elevation or lower than that of the light-emitting devices. Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. As used herein, a light-emitting stack structure, a light-emitting device, or a light-emitting package may include micro-LEDs, having a light-emitting area of ​​10,000 pm2 or less, as is well known in the art. In other exemplary embodiments, the micro-LED may have a light-emitting area of ​​4,000 pm2 or less, and, furthermore, 2,500 pm2 or less. FIG. 1A is a schematic perspective view of a light emitting device according to an exemplary embodiment, FIG. 1B is a schematic plan view of the light emitting device of FIG. 1A, and FIG. 1C and FIG. 1D are schematic cross-sectional views taken along lines AA' and BB' of FIG. 1B, respectively. Referring to FIGS. 1A and 1B, a light-emitting device 100 includes a light-emitting stack structure, a first connecting electrode 20ce, a second connecting electrode 30ce, a third connecting electrode 40ce, and a fourth connecting electrode 50ce formed in the light-emitting stack structure, and a protective layer 90 surrounding the connecting electrodes 20ce, 30ce, 40ce, and 50ce. An array of light-emitting devices 100 may be formed on a substrate 11, and the light-emitting device 100 illustrated in FIG. 1A shows the singulation of the array, and thus may be referred to as a light-emitting device. The configuration and singulation of the light-emitting devices 100 will be described in more detail later.In some exemplary embodiments, the light-emitting device 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 more detail below. With reference to FIGS. 1A-1D , the light-emitting device 100 according to the illustrated exemplary embodiment may include a light-emitting stack structure, and include a first LED subunit, a second LED subunit, and a third LED subunit disposed 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 is exemplarily shown as including three light-emitting stacks 20, 30, and 40, but the inventive concepts are not limited to a specific number of light-emitting stacks. For example, in some exemplary embodiments, the light-emitting stack structure may include two or more light-emitting stacks.Hereinafter, the light-emitting stack structure will be exemplarily described as including three light-emitting stacks 20, 30 and 40. The substrate 11 may include a light-transmissive insulating material for transmitting light. However, in some exemplary embodiments, the substrate 11 may be formed to be translucent or partially transparent to transmit only light of a specific wavelength or only a portion of light of a specific wavelength. The substrate 11 may be a growth substrate for epitaxially growing the third light-emitting stack 40 thereon, for example, a sapphire substrate. However, the substrate 11 is not limited to the sapphire substrate, and may include other transparent insulating materials. For example, the substrate 11 may include glass, quartz, silicon, an organic polymer, or an organic-inorganic composite material, such as silicon carbide (SiC), gallium nitride (GaN), indium gallium nitride (InGaN), aluminum gallium nitride (AlGaN), aluminum nitride (AIN), gallium oxide (GazOs), or a silicon substrate.Furthermore, the substrate 11 may include irregularities on an upper surface thereof and, for example, may be a patterned sapphire substrate. The irregularities formed on the upper surface of the substrate 11 may increase the extraction efficiency of light generated in the third light-emitting stack 40 that is in contact with the substrate 11. The irregularities of the substrate 11 may be included to selectively increase the luminous intensity of the third light-emitting stack 40 as compared to those of the first light-emitting stack 20 and the second light-emitting stack 30. In another exemplary embodiment, the substrate 11 may be eliminated. The first, second, and third light-emitting stacks 20, 30, and 40 are configured to emit light toward the substrate 11. Accordingly, light emitted from the first light-emitting stack 20 may pass through the second and third light-emitting stacks 30 and 40. According to an exemplary embodiment, the first, second, and third light-emitting stacks 20, 30, and 40 may emit light with different peak wavelengths from each other. In an exemplary embodiment, a light-emitting stack disposed farther from the substrate 11 emits light having a longer wavelength than light emitted by a light-emitting stack disposed closer to the substrate 11, such that light loss may be reduced. For example, the first light-emitting stack 20 may emit red light, the second light-emitting stack 30 may emit green light, and the third light-emitting stack 40 may emit blue light. In another exemplary embodiment, to adjust a color mixing ratio of the first, second, and third light-emitting stacks 20, 30, and 40, the second light-emitting stack 30 may emit light of a shorter wavelength than that of the third light-emitting stack 40. Accordingly, the luminous intensity of the second light-emitting stack 30 may be reduced, and the luminous intensity of the third light-emitting stack 40 may be increased, and therefore, the luminous intensity ratios of the light emitted from the first, second, and third light-emitting stacks may be significantly changed. For example, the first light-emitting stack 20 may be configured to emit red light, the second light-emitting stack 30 may be configured to emit blue light, and the third light-emitting stack 40 may be configured to emit green light.In this way, the luminous intensity of the blue light can be relatively reduced, and the luminous intensity of the green light can be relatively increased, and thus, the luminous intensity ratios of the red, green, and blue light can be easily adjusted to approach 3:6:1. Furthermore, the light-emitting areas of the first, second, and third light-emitting stacks 20, 30, and 40 may be about 10,000 pm2 or less, 4,000 pm2 or less, or 2,500 pm2 or less, depending on an application. Furthermore, as the light-emitting stack is disposed closer to the substrate 11, the emitting area may be larger. As such, since the third light-emitting stack 40 emitting green light is disposed closest to the substrate 11, the luminous intensity of the green light may further increase. Hereinafter, while the second light-emitting cell 30 is exemplarily described as emitting light of a shorter wavelength than that emitted by the third light-emitting cell 40, it should be noted that the second light-emitting cell 30 emits light of a longer wavelength than that emitted by the third light-emitting cell 40, such as green light. The first light-emitting stack 20 includes a first conductive semiconductor layer 21, an active layer 23, and a second conductive semiconductor layer 25. According to an exemplary embodiment, the first light-emitting stack 20 may include a semiconductor material, such as AlGaAs, GaAsP, AlGalnP, and GaP that emits red light, but the inventive concepts are not limited thereto.

[0061] A first upper contact electrode 21 n may be disposed on the first conductive semiconductor layer 21 to be in ohmic contact with the first conductive semiconductor layer 21. A first lower contact electrode 25p may be disposed beneath the second conductive semiconductor layer 25.According to an exemplary embodiment, a portion of the first conductive semiconductor layer 21 may be patterned and recessed, and the first top contact electrode 21 n may be disposed in the recessed region of the first conductive semiconductor layer 21 to increase an ohmic contact level. The first top contact electrode 21 n may have a single-layer structure or a multi-layer structure, and may include Al, Ti, Cr, Ni, Au, Ag, Sn, W, Cu, or an alloy thereof, such as Au-Te alloy or Au-Ge alloy, but the inventive concepts are not limited thereto. In an exemplary embodiment, the first top contact electrode 21 n may have a thickness of about 100 nm, and may include a metal having a high reflectivity to increase light emission efficiency in a downward direction toward the substrate 11. The second light-emitting stack 30 includes a first conductive semiconductor layer 31, an active layer 33, and a second conductive semiconductor layer 35. According to an exemplary embodiment, the second light-emitting stack 30 may include a semiconductor material, such as GaN, InGaN, ZnSe that emits blue light, but the inventive concepts are not limited thereto. A second lower contact electrode 35p is disposed beneath the second conductive semiconductor layer 35 of the second light-emitting stack 30. The third light-emitting stack 40 includes a first conductive semiconductor layer 41, an active layer 43, and a second conductive semiconductor layer 45. According to an exemplary embodiment, the third light-emitting stack 40 may include a semiconductor material, such as GaN, InGaN, GaP, AlGalnP, AlGaP, or the like that emits green light. A third lower contact electrode 45p is disposed on the second conductive semiconductor layer 45 of the third light-emitting stack 40. According to an exemplary embodiment, each of the first conductive semiconductor layers 21, 31, and 41 and the second conductive semiconductor layers 25, 35, and 45 of the first, second, and third light-emitting stacks 20, 30, and 40 may have a single-layer structure or a multi-layer structure, and in some exemplary embodiments, may include a superlattice layer. Furthermore, the active layers 23, 33, and 43 of the first, second, and third light-emitting stacks 20, 30, and 40 may have a single quantum well structure or a multiple quantum well structure. Each of the first, second, and third lower contact electrodes 25p, 35p, and 45p may include a transparent conductive material that transmits light. For example, the lower contact electrodes 25p, 35p, and 45p may include transparent conductive oxide (TCO), such as, but not limited to, SnO, InOz, ZnO, ITO, ITZO, or the like. A first adhesive layer 61 is disposed between the first light-emitting stack 20 and the second light-emitting stack 30, and a second adhesive layer 63 is disposed between the second light-emitting stack 30 and the third light-emitting stack 40. The first and second adhesive layers 61 and 63 may include a non-conductive material that transmits light. For example, the first and second adhesive layers 61 and 63 may include an optically clear adhesive (OCA), which may include epoxy, polyimide, SU8, spin-on-glass (SOG), benzocyclobutene (BCB), but the inventive concepts are not limited thereto. In accordance with the illustrated exemplary embodiment, a first insulating layer 81 and a second insulating layer 83 are disposed on at least portions of the side surfaces 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 may include various organic or inorganic insulating materials, such as polyimide, SiO2, SiNx, Al2O3, or the like. For example, at least one of the first and second insulating layers 81 and 83 may include a distributed Bragg reflector (DBR). As another example, at least one of the first and second insulating layers 81 and 83 may include a black organic polymer. In some exemplary embodiments, an electrically buoyant metallic reflection layer is disposed on the first and second insulating layers 81 and 83 and can reflect light emitted from the light-emitting stacks 20, 30 and 40 toward the substrate 11.In some exemplary embodiments, at least one of the first and second insulating layers 81 and 83 may have a single-layer structure or a multi-layer structure formed by two or more insulating layers having different refractive indices. According to an exemplary embodiment, each of the first, second, and third light-emitting stacks 20, 30, and 40 may be driven independently. More specifically, a common voltage may be applied to one of the first and second conductive semiconductor layers of each of the light-emitting stacks, and an individual emission signal may be applied to the remaining one of the first and second conductive semiconductor layers of each of the light-emitting stacks. For example, according to an exemplary embodiment, the first conductive semiconductor layers 21, 31, and 41 of each of the light-emitting stacks 20, 30, and 40 may be n-type, and the second conductive semiconductor layers 25, 35, and 45 of each of the light-emitting stacks 20, 30, and 40 may be p-type.In this case, the third light-emitting stack 40 may have a stacking sequence opposite to that of the first light-emitting stack 20 and the second light-emitting stack 30, and therefore, the p-type semiconductor layer 45 may be disposed on the active layer 43 to simplify manufacturing processes for the light-emitting device 100. Hereinafter, the semiconductor layers of the first conductive type and the second conductive type may exemplarily be described as n-type and p-type, respectively. In some exemplary embodiments, however, the n-type and p-type may be reversed. Each of the first, second, and third lower contact electrodes 25p, 35p, and 45p that are connected to the p-type semiconductor layers 25, 35, and 45 of the light-emitting cells, respectively, may be electrically connected to the first, second, and third connection electrodes 20ce, 30ce, and 40ce to receive corresponding light-emitting signals, respectively. Meanwhile, the n-type semiconductor layers 21, 31, and 41 of the light-emitting cells may be commonly electrically connected to the fourth connection electrode 50ce. As such, the light-emitting device 100 may have a common n-type light-emitting cell structure, in which the n-type semiconductor layers 21, 31, and 41 of the first, second, and third light-emitting cells 20, 30, and 40 are commonly connected, and can be driven independently of each other.Since the light emitting device 100 has the common n-type light emitting structure, the voltage sources applied to the first, second and third light emitting cells 20, 30 and 40 can be adjusted to be different from each other. The light-emitting device 100 according to the illustrated exemplary embodiment has the common n-type structure, but the inventive concepts are not limited thereto. For example, in some exemplary embodiments, the first conductive semiconductor layers 21, 31, and 41 of each of the light-emitting stacks may be p-type, and the second conductive semiconductor layers 25, 35, and 45 of each of the light-emitting stacks may be n-type, and thus, a common p-type light-emitting stack structure may be formed. Furthermore, in some exemplary embodiments, the stacking sequence of each of the light-emitting stacks is not limited to that shown in the drawing, but may be variously modified. Hereinafter, the light-emitting device 100 will be exemplarily described as having the common n-type light-emitting stack structure. According to the illustrated exemplary embodiment, the light emitting device 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 the first lower contact electrode 25p through a first contact hole 20CH defined through the first insulating layer 81. The first connection electrode 20ce is electrically connected to the first pad 20pd through a first through hole 20ct defined through the second insulating layer 83. The second pad 30pd is electrically connected to the second lower contact electrode 35p through a second contact hole 30CH defined through the first insulating layer 81. The second connection electrode 30ce is electrically connected to the second pad 30pd through a second through hole 30ct defined through the second insulating layer 83.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 connection 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 electrically connected to the first conductive type semiconductor layers 21, 31 and 41 of the first, second and third light emitting cells 20, 30 and 40 via a first sub-contact hole 50CHa, a second sub-contact hole 50CHb and a third sub-contact hole 50CHc defined in the first conductive type semiconductor layers 21, 31 and 41 of the first, second and third light emitting cells 20, 30 and 40.In particular, the first subcontact 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 through the first subcontact hole 50CHa. In this manner, the fourth pad 50pd may be electrically connected to the first conductive semiconductor layers 21, 31, and 41 through the subcontact holes 50CHa, 50CHb, 50CHc, so that manufacturing processes of the light-emitting device 100 may be simplified. The fourth connection electrode 50ce is electrically connected to the fourth pad 50pd through a fourth through hole 50ct defined through the second insulating layer 83. In the illustrated exemplary embodiment, although each of the connection electrodes 20ce, 30ce, 40ce, and 50ce are shown and described as being in direct contact with the pads 20pd, 30pd, 40pd, and 50pd, in some exemplary embodiments, the connection electrodes 20ce, 30ce, 40ce, and 50ce may not be directly connected to the pads 20pd, 30pd, 40pd, and 50pd, and other connectors may be interposed therebetween. The first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd are separated and insulated from each other. According to an exemplary embodiment, each of the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd may cover at least portions of the side surfaces of the first, second, and third light-emitting stacks 20, 30, and 40. In this manner, heat generated by the first, second, and third light-emitting stacks 20, 30, and 40 may be easily dissipated. According to the illustrated exemplary embodiment, each of the connection electrodes 20ce, 30ce, 40ce and 50ce may have a substantially elongated shape protruding upwardly from the substrate 11. The connection electrodes 20ce, 30ce, 40ce, and 50ce may include metal, such as Cu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag, or an alloy thereof, but the inventive concepts are not limited thereto. For example, each of the connection electrodes 20ce, 30ce, 40ce, and 50ce may include two or more metals or a plurality of different metal layers to reduce stress from the elongated shape of the connection electrodes 20ce, 30ce, 40ce, and 50ce. In another exemplary embodiment, when the connection electrodes 20ce, 30ce, 40ce, and 50ce include Cu, an additional metal may be deposited or plated to inhibit oxidation of the Cu. In some exemplary embodiments, when the connection electrodes 20ce, 30ce, 40ce, and 50ce include Cu / Ni / Sn, the Cu may prevent Sn from penetrating the light-emitting stack structure.In some exemplary embodiments, the connecting electrodes 20ce, 30ce, 40ce, and 50ce may include a seed layer to form a metallic layer in a plating process, which will be described in more detail below. As shown in the drawings, each of the connection electrodes 20ce, 30ce, 40ce, and 50ce may have a substantially flat upper surface, thereby facilitating electrical connection between the external lines or electrodes and the light-emitting stack structure. According to an exemplary embodiment, when the light-emitting device 100 includes micro LEDs having a surface area of ​​about 10,000 pm2 or less, about 4,000 pm2 or less, or about 2,500 pm2 or less, as is known in the art, the connection electrodes 20ce, 30ce, 40ce, and 50ce may overlap with at least a portion of one of the first, second, and third light-emitting stacks. 20, 30, and 40, as shown in the drawing. More specifically, the connecting electrodes 20ce, 30ce, 40ce, and 50ce may be overlapped by at least one step formed on the side surface of the light-emitting stack structure. As such, since a lower surface of the connecting electrode provides a larger contact area than an upper surface thereof, a large contact area may be formed between the connecting electrodes 20ce, 30ce, 40ce, and 50ce and the light-emitting stack structure. Accordingly, the connecting electrodes 20ce, 30ce, 40ce, and 50ce may be formed more stably in the light-emitting stack structure than those of a conventional light-emitting device.For example, lengths L1, L2, L3, and L4 of an outward-facing side surface of the connecting electrodes 20ce, 30ce, 40ce, and 50ce may be different from lengths L1', L2', L3', and L4' of a side surface facing a center of the light-emitting device 100. More specifically, a length of one outward-facing side surface of the connecting electrode may be longer than that of another center-facing side surface of the light-emitting device 100. For example, a difference in lengths L and L' of two mutually opposite surfaces may be larger than a thickness (or height) of one of the light-emitting stacks 20, 30, and 40. In this way, the structure of the light-emitting device 100 may be strengthened with a larger contact area between the connecting electrodes 20ce, 30ce, 40ce, and 50ce and the structure of the light-emitting stack.Furthermore, since the connecting electrodes 20ce, 30ce, 40ce and 50ce can be overlapped with at least one step formed on the side surface of the light-emitting stack structure, heat generated in the light-emitting stack structure can be dissipated to the outside more efficiently. According to an exemplary embodiment, a difference between the length L1, L2, L3, or L4 of one side surface of the connecting electrode facing outward and the lengths L1', L2', L3', and L4' of the other side surface facing the center of the light-emitting device 100 may be about 3 pm. In this case, the structure of the light-emitting stack may be formed thinly, and in particular, the first light-emitting stack 20 may have a thickness of about 1 pm, the second light-emitting stack 30 may have a thickness of about 0.7 pm, the third light-emitting stack 40 may have a thickness of about 0.7 pm, and each of the first and second adhesive layers may have a thickness of about 0.2 pm to about 0.3 pm, but the inventive concepts are not limited thereto.According to another exemplary embodiment, a difference between the length L1, L2, L3, or L4 of one side surface of the connecting electrode facing outward and the lengths L1, L2', L3', and L4' of the other side surface facing the center of the light-emitting device 100 may be from about 10 pm to about 16 pm. In this case, the structure of the light-emitting stack may be formed to be relatively thick and have a more stable structure, and in particular, the first light-emitting stack 20 may have a thickness of from about 4 pm to about 5 pm, the second light-emitting stack 30 may have a thickness of about 3 pm, the third light-emitting stack 40 may have a thickness of about 3 pm, and each of the first and second adhesive layers may have a thickness of about 0.3 pm, but the inventive concepts are not limited thereto.According to another exemplary embodiment, a difference between the length L1, L2, L3, or L4 of one side surface of the connection electrode facing outward and the lengths LT, L2', L3', and L4' of the other side surface facing the center of the light-emitting device 100 may be about 25% of a length of a larger side surface. However, the inventive concepts are not limited to a particular difference in lengths between the two surfaces of the connection electrode opposite each other, and the difference in lengths between the two surfaces opposite each other may be changed in other exemplary embodiments. In some exemplary embodiments, at least one of the connection electrodes 20ce, 30ce, 40ce, and 50ce may be overlapped with the side surface of each of the light-emitting stacks 20, 30, and 40, and therefore, the light-emitting stacks 20, 30, and 40 can efficiently dissipate heat generated therein. Furthermore, when the connection electrodes 20ce, 30ce, 40ce, and 50ce include a reflective material such as metal, the connection electrodes 20ce, 30ce, 40ce, and 50ce can reflect light emitted from at least one of the light-emitting stacks 20, 30, and 40, and therefore, the luminous efficiency can be improved. Generally, during the manufacturing process, an array of a plurality of light-emitting devices is formed on a substrate. The substrate is cut along a scribe line to single out (separate) each of the light-emitting devices, and the light-emitting device may be transferred to another substrate or to a belt using various transfer techniques for further processing of the light-emitting devices, such as packaging. In this case, when the light-emitting device includes connecting electrodes, such as metal protrusions or pillars that protrude outward from the light-emitting structure, during a subsequent process, for example, a transfer step, various problems may occur due to the light-emitting device structure protruding outward.Additionally, when the light-emitting device includes micro-LEDs that have a surface area of ​​about 10,000 pm2 or less, about 4,000 pm2 or less, or about 2,500 pm2 or less, depending on the application, handling of the light-emitting device may be more difficult due to its small form factor. For example, when the connecting electrode has a substantially elongated shape, such as a rod, transferring the light-emitting device using a conventional vacuum method may be difficult because the light-emitting device may not have a sufficient suction area due to the protruding structure of the connecting electrode. Furthermore, the exposed connecting electrode may be directly affected by various stresses during a subsequent process, such as when the connecting electrode comes into contact with a manufacturing apparatus, which may damage the structure of the light-emitting device. As another example, when the light-emitting device is transferred by affixing an adhesive tape to the upper surface of the light-emitting device (e.g., a surface opposite the substrate), a contact area between the light-emitting device and the adhesive tape may be limited to the upper surface of the connecting electrode.In this case, unlike when the adhesive tape is adhered to the bottom surface of the light-emitting device (e.g., the substrate), the adhesive force of the light-emitting device to the adhesive tape may be weakened, and the light-emitting device may undesirably separate from the adhesive tape while the light-emitting device is being transferred. As another example, when the light-emitting device is transferred using a conventional pick-and-place method, a discharge pin may directly contact a portion of the light-emitting device disposed between the connecting electrodes, and thus, an upper structure of the light-emitting structure may be damaged. In particular, the discharge pin may strike the center of the light-emitting device, causing physical damage to an upper light-emitting stack of the light-emitting device. According to an exemplary embodiment, the protective layer 90 may be formed on the light-emitting stack structure. More specifically, as shown in FIG. 1A , the protective layer 90 may be formed between the connection electrodes 20ce, 30ce, 40ce, and 50ce to cover at least the side surface of the light-emitting stack structure. According to the illustrated exemplary embodiment, the protective layer 90 may expose the side surfaces of the substrate 11, the first and second insulating layers 81 and 83, and the third light-emitting stack 40. The protective layer 90 may be formed to be substantially flush with the top surfaces of the connection electrodes 20ce, 30ce, 40ce, and 50ce, and may include an epoxy molding compound (EMC), which may be formed in various colors, such as black, white, or clear. However, the inventive concepts are not limited thereto.For example, in some exemplary embodiments, the protective layer 90 may include polyimide (PID), and in this case, the PID may be provided as a dry film rather than a liquid type to increase flatness when the PID is applied to the light-emitting stack structure. In some exemplary embodiments, the protective layer 90 may include a photosensitive substance. In this way, the protective layer 90 may provide sufficient contact area to the light-emitting device 100 not only to protect the light-emitting structure from external impacts that may be applied during subsequent processes, but also to facilitate handling during the subsequent transfer step. Furthermore, the protective layer 90 may prevent light leakage from the side surface of the light-emitting device 100 to avoid or at least suppress interference from light emitted from an adjacent light-emitting device 100. FIG. 2 is a schematic cross-sectional view of a light-emitting stack structure according to an exemplary embodiment. Since the light-emitting stack structure according to the illustrated exemplary embodiment is substantially the same as that included in the light-emitting device 100 described above, repeated descriptions of substantially the same elements will be omitted to avoid redundancy. Referring to FIG. 2, the first, second, and third lower contact electrodes 25p, 35p, and 45p according to an exemplary embodiment may be connected to individual lines SR, SG, and SB, respectively. The first conductive semiconductor layers 21, 31, and 41 of the first, second, and third light-emitting cells 20, 30, and 40 may be connected to a common line Se. The common line Se may be connected to the first conductive semiconductor layer 21 of the first light-emitting cell 20 via a first upper contact electrode 21 n. According to an exemplary embodiment, different voltages may be applied to the first, second, and third light-emitting cells 20, 30, and 40 by including an n-common structure. For example, a relatively low voltage may be applied to the first light-emitting cell 20 emitting red light compared to those applied to the second and third light-emitting cells 30 and 40 emitting blue light and green light. Therefore, a suitable voltage source for each of the light-emitting cells may be used individually to reduce power loss. In the illustrated exemplary embodiment, the first, second, and third light-emitting cells 20, 30, and 40 may be individually controlled to selectively emit light using the individual lines SR, SG, and SB and the common line Se. FIG. 2 exemplarily shows the structure of the light-emitting stack having the n-common structure, but the inventive concepts are not limited thereto. For example, in some exemplary embodiments, the common line Se may be electrically connected to the lower contact electrodes 25p, 35p, and 45p of the first, second, and third light-emitting stacks 20, 30, and 40, and the individual lines SR, SG, and SB may be connected to the first conductive semiconductor layers 21, 31, and 41 of the first, second, and third light-emitting stacks 20, 30, and 40, respectively. The light-emitting stack structure according to an exemplary embodiment can display light having a plurality of colors based on an operating state of each of the light-emitting stacks 20, 30, and 40, whereas conventional light-emitting devices can display a plurality of colors in a combination of multiple light-emitting cells emitting light of a single color. More specifically, conventional light-emitting devices generally include light-emitting cells spaced apart from one another along a two-dimensional plane and emitting light of different colors, e.g., red, green, and blue, respectively, to realize a full-color display. In this way, the conventional light-emitting cells can occupy a relatively large area.However, the light-emitting stack structure according to an exemplary embodiment can emit light of different colors by stacking a plurality of light-emitting stacks 20, 30 and 40, and therefore, the light-emitting stack structure can provide a high level of integration and realize full-color display across a smaller area than that of the conventional light-emitting apparatus. Furthermore, when the light-emitting devices 100 are mounted on another substrate to manufacture a display apparatus, the number of devices to be mounted can be significantly reduced compared to the conventional light-emitting device. As such, particularly when hundreds of thousands or millions of pixels are formed in a display apparatus, the manufacturing of the display apparatus utilizing the light-emitting device 100 can be substantially simplified. According to an exemplary embodiment, the light-emitting stack structure may further include various additional elements to improve the purity and efficiency of the light emitted therefrom. For example, in some exemplary embodiments, a wavelength-pass filter may be disposed between the light-emitting stacks. In some exemplary embodiments, an irregularity portion may be formed on a light-emitting surface of at least one of the light-emitting stacks to balance the brightness of the light between the light-emitting stacks. For example, the luminous intensity of green light should be increased so that the RGB mixing ratio is close to 3:6:1. As such, irregularities may form on the surface of the substrate 11. Next, a method of forming the light emitting device 100 according to an exemplary embodiment will be described with reference to the accompanying drawings. FIGS. 3A , 4A , 5A , 6A , 7A , and 8A are plan views illustrating a manufacturing process of the light-emitting device of FIG. 1A according to an exemplary embodiment. FIGS. 3B , 4B , 5B , 6B , 7B , and 8B are cross-sectional views taken along line AA' of corresponding plan views shown in FIGS. 3A , 4A , 5A , 6A , 7A , and 8A according to an exemplary embodiment. FIGS. 4C , 5C , 6C , 7C , and 8C are cross-sectional views taken along line BB' of corresponding plan views shown in FIGS. 3A , 4A , 5A , 6A , 7A , and 8A according to an exemplary embodiment. FIGS. 9, 10, 11, 12 and 13 are cross-sectional views schematically showing a manufacturing process of the light emitting device of FIG. 1A according to an exemplary embodiment. Returning to FIG. 2, the first conductive semiconductor layer 41, the third active layer 43, and the second conductive semiconductor layer 45 of the third light-emitting stack 40 may 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 bottom 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 include transparent conducting oxide (TCO), such as SnO, βθ2, ZnO, ITO, βTZO, or the like. When the third light-emitting stack 40 emits green light according to an exemplary embodiment, the substrate 11 may include AI2O3 (e.g., a sapphire substrate), and the third lower contact electrode 45p may include transparent conductive oxide (TCO), such as tin oxide.The first and second light-emitting stacks 20 and 30 may be similarly formed by sequentially growing the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer on a temporary substrate, respectively. The bottom contact electrodes including transparent conducting oxide (TCO) may be formed, for example, by a physical vapor deposition method or a chemical vapor deposition method on the second conductive semiconductor layer, respectively. Furthermore, the first and second light-emitting stacks 20 and 30 may be coupled to each other with the first adhesive layer 61 interposed therebetween, and at least one of the temporary substrates of the first and second light-emitting stacks 20 and 30 may be removed by a laser peeling process, a chemical process, a mechanical process, or the like.The first and second light-emitting stacks 20 and 30 may then be coupled to the third light-emitting stack 40 with the second adhesive layer 63 therebetween, and the remaining temporary substrate of the first or second light-emitting stacks 20 and 30 may be removed by a laser peeling process, a chemical process, a mechanical process, or the like. With reference to FIGS. 3A, 3B and 3C, various portions of each of the first, second and third light-emitting stacks 20, 30 and 40 may be patterned by an etching process or the like to form a first conductive semiconductor layer 21, a first lower contact electrode 25p, a first conductive semiconductor layer 31, a second lower contact electrode 35p, a third lower contact electrode 45p and a first conductive semiconductor layer 41. According to the illustrated exemplary embodiment, the first light-emitting stack 20 has the smallest area among the light-emitting stacks 20, 30 and 40. The third light-emitting stack 40 may have the largest area among the light-emitting stacks 20, 30 and 40, and therefore, the luminous intensity of the third light-emitting stack 40 may be relatively greater.However, the inventive concepts are not particularly limited to the relative sizes of the light-emitting batteries 20, 30 and 40. Referring to FIGS. 4A, 4B, and 4C, a portion of an upper surface of the first conductive semiconductor layer 21 of the first light-emitting stack 20 may be patterned through wet etching or the like to form a first upper contact electrode 21 n. As described above, the first upper contact electrode 21 n is formed to have a thickness of about 100 nm in the recessed region of the first conductive semiconductor layer 21, to enhance an ohmic contact therebetween. Referring to FIGS. 5A, 5B, and 5C, a first insulating layer 81 may be formed to cover the light-emitting cells 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 openings 20CH, 30CH, 40CH, and 50CH. The first contact opening 20CH is defined at the first lower contact electrode 25p to expose a portion of the first lower contact electrode 25p. The second contact opening 30CH is defined at the second lower contact electrode 35p and may expose a portion of the second lower contact electrode 35p. The third contact opening 40CH is defined at the third lower contact electrode 45p and may expose a portion of the third lower contact electrode 45p. The fourth contact hole 50CH provides a passageway for electrical connection to the first conductive semiconductor layers 21, 31 and 41 of the first, second and third light-emitting stacks 20, 30 and 40. The fourth contact hole 50CH may include a first sub-contact hole 50CHa, a second sub-contact hole 50CHb and a third sub-contact hole 50CHc. The first sub-contact hole 50CHa may be defined in the first conductive type semiconductor layer 21 to expose a portion of the first upper contact electrode 21 n, and the second sub-contact hole 50CHb may be defined in the first conductive type semiconductor layer 31 to expose a portion of the first conductive type semiconductor layer 31, and the third sub-contact hole 50CHc may be defined in the first conductive type semiconductor layer 41 to expose a portion of the first conductive type semiconductor layer 41. Referring to FIGS. 6A, 6B and 6C, first, second, third and fourth pads 20pd, 30pd, 40pd and 50pd are formed in the first insulating layer 81 including the 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 on substantially the entire surface of the structure, and patterning the conductive layer using a photolithography process. The first pad 20pd may be formed to overlap a region in which the first contact hole 20CH is formed, and may be connected to the first lower contact electrode 25p through the first contact hole 20CH. The second pad 30pd may be formed to overlap a region in which the second contact hole 30CH is formed, and may be connected to the second lower contact electrode 35p through the second contact hole 30CH. The third pad 40pd may be formed to overlap a region in which the third contact hole 40CH is formed, and may be connected to the third lower contact electrode 45p through the third contact hole 40CH.The fourth pad 50pd may be formed to overlap with a region in which the fourth contact hole 50CH is formed, in particular the regions in which the first, second and third sub-contact holes 50CHa, 50CHb and 50CHc are formed, and may be electrically connected to the first conductive type semiconductor layers 21, 31 and 41 of the light-emitting stacks 20, 30 and 40. Referring to FIGS. 7A, 7B, and 7C, a second insulating layer 83 may be formed over the first insulating layer 81. The second insulating layer 83 may include silicon oxide and / or silicon nitride. However, the inventive concepts are not limited thereto, and in some exemplary embodiments, the first and second insulating layers 81 and 83 may include inorganic materials. The second insulating layer 83 may then be patterned, and first, second, third, and fourth through holes 20ct, 30ct, 40ct, and 50ct may be formed exposing the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd. The first through hole 20ct formed in the first pad 20pd exposes a portion of the first pad 20pd. The second through hole 30ct formed in the second pad 30pd exposes a portion of the second pad 30pd. The third through hole 40ct formed in the third pad 40pd exposes a portion of the third pad 40pd. The fourth through hole 50ct formed in 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 may be defined within the regions in which the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd are formed, respectively. Referring to FIGS. 8A, 8B and 8C, the first, second, third and fourth connection electrodes 20ce, 30ce, 40ce and 50ce are formed in the second insulating layer 83 in which the first, second, third and fourth through holes 20ct, 30ct, 40ct and 50ct are formed. The first connection electrode 20ce may be formed to overlap with a region in which the first through hole 20ct is formed, and may be connected to the first pad 20pd through the first through hole 20ct. The second connection electrode 30ce may be formed to overlap with a region where the second through hole 30ct is formed, and may be connected to the second pad 30pd through the second through hole 30ct. The third connection electrode 40ce may be formed to overlap with a region in which the third through hole 40ct is formed, and may be connected to the third pad 40pd through the third through hole 40ct.The fourth connection electrode 50ce may be formed to overlap with a region in which the fourth through hole 50ct is formed, and may be connected to the fourth pad 50pd through the fourth through hole 50ct. The first, second, third, and fourth connection electrodes 20ce, 30ce, 40ce, and 50ce are formed in the light-emitting cell structure and are spaced apart from each other. The first, second, third, and fourth connection electrodes 20ce, 30ce, 40ce, and 50ce may be electrically connected to the first, second, third, and fourth pads 20pd, 30pd, 40pd, and 50pd, respectively, and transmit an external signal to each of the light-emitting cells 20, 30, and 40. A method of forming the first, second, third, and fourth connecting electrodes 20ce, 30ce, 40ce, and 50ce is not particularly limited. For example, according to an exemplary embodiment, a seed layer is deposited as a conductive surface on the light-emitting stack structure, and a photoresist pattern may be formed such that the seed layer is exposed at a location where the connecting electrodes will be formed. According to an exemplary embodiment, the initial layer may be deposited to have a thickness of approximately 1000A, but the inventive concepts are not limited thereto. Subsequently, the seed layer may be plated with metal, such as Cu, Ni, Ti, Sb, Zn, Mo, Co, Sn, Ag, or an alloy thereof, and the photoresist pattern and the seed layer remaining between the connecting electrodes may be removed.In some exemplary embodiments, to prevent or at least inhibit oxidation of the plated metal, an additional metal with electroless nickel immersion gold (ENIG) or similar material may be deposited or plated onto the plated metal (e.g., the connecting electrodes). In some exemplary embodiments, the seed layer may be retained on each of the connecting electrodes. According to the illustrated exemplary embodiment, each of the connection electrodes 20ce, 30ce, 40ce, and 50ce may have a substantially elongated shape to be spaced from the substrate 11. In another exemplary embodiment, the connection electrodes 20ce, 30ce, and 40ce may include two or more metals or a plurality of different metal layers to reduce stress from the elongated shape of the connection electrodes 20ce, 30ce, 40ce, and 50ce. However, the inventive concepts are not limited to a specific shape of the connection electrodes 20ce, 30ce, 40ce, and 50ce, and in some exemplary embodiments, the connection electrode may have multiple shapes. As shown in the drawings, each of the connection 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 outer electrodes or lines. The connection electrodes 20ce, 30ce, 40ce, and 50ce may be overlapped by at least one step formed on the side surface of the light-emitting stack structure. In this way, a lower surface of the connection electrode may provide a larger contact area between the connection electrodes 20ce, 30ce, 40ce, and 50ce and the light-emitting stack structure than an upper surface thereof, and therefore, the light-emitting device 100 together with a protective layer 90 may have a more stable structure that is capable of withstanding various subsequent processes.In this case, a length L (L1 to L4) of one side surface of the connecting electrodes 20ce, 30ce, 40ce, and 50ce facing outward and a length L' (L11 to L4') of another surface facing a center of the light-emitting device 100 may be different. For example, a difference in lengths between two surfaces of the connecting electrode opposite each other may be from about 3 pm to about 16 pm, but is not limited thereto. Next, the protective layer 90 is disposed between the connection electrodes 20ce, 30ce, 40ce, and 50ce. The protective layer 90 may be formed to be substantially flush with the upper surfaces of the connection electrodes 20ce, 30ce, 40ce, and 50ce by a polishing or similar process. According to an exemplary embodiment, the protective layer 90 may include a black epoxy molding compound (EMC), but the inventive concepts are not limited thereto. For example, in some exemplary embodiments, the protective layer 90 may include a photosensitive polyimide (PID) dry film. In this manner, the protective layer 90 may provide sufficient contact area to the light-emitting device 100 not only to protect the light-emitting structure from external impacts that may be applied during subsequent processes, but also to facilitate handling during a subsequent transfer step.In addition, the shielding layer 90 can prevent light leakage from the side surface of the light emitting device 100 to prevent or at least suppress interference from light emitted from adjacent light emitting devices 100. FIG. 9 exemplarily shows a plurality of light-emitting devices 100 disposed on the substrate 11, and a singulation process is applied to separate the light-emitting devices 100. With reference to FIG. 10, according to an exemplary embodiment, laser beams may be irradiated between the light-emitting stack structures to form a separation path that partially separates the light-emitting stack structures. With reference to FIG. 11, a separation path may be added in the substrate 11 using a stealth laser. The stealth laser may be irradiated in a direction opposite to a surface to which the laser of FIG. 10 is irradiated. Referring to FIG. 12, the substrate 11 with a first bonding layer 95 adhered thereto may be cut or ruptured using various methods that are well known in the art. For example, the substrate 11 may be cut by cutting the substrate 11 across a scribe line formed therein, or it may be ruptured by applying a mechanical force along the separation path formed during a laser irradiation process. The first bonding layer 95 may be an adhesive tape, but the inventive concepts are not limited thereto, so long as the first bonding layer 95 can stably bond the light-emitting devices 100, being capable of separating the light-emitting devices 100 in a subsequent process. Although the first bonding layer 95 has been described above as being bonded to the substrate 11 after the laser irradiation step, the first bonding layer 95 may be bonded to the substrate 11 prior to the laser irradiation step in other exemplary embodiments. Referring to FIG. 13, after the substrate 11 is separated into individual light-emitting devices 100, the first bonding layer 95 may be expanded, and accordingly, the light-emitting devices 100 may be spatially separated from one another. FIGS. 14, 15A, 15B, and 16A are cross-sectional views schematically illustrating a manufacturing process for a light-emitting package according to an exemplary embodiment, and FIG. 16B is a plan view of a light-emitting package according to an exemplary embodiment. The light-emitting device 100 according to an exemplary embodiment may be transferred and packaged in various manners well known in the art. Hereinafter, although a second adhesive layer 13 is illustrated attached to the substrate 11 via a carrier substrate 11c for transferring the light-emitting device 100, the inventive concepts are limited to a specific transfer method. Referring to FIG. 14, according to an exemplary embodiment, the singled light-emitting device 100 may be transferred to the carrier substrate 11c with the second adhesive layer 13 disposed therebetween. In this case, when the light-emitting device 100 includes connecting electrodes protruding outwardly from the light-emitting stack structure without a protective layer 90, various problems may occur in subsequent processes, particularly in a transfer process, due to the non-uniform structure as described above. Furthermore, when the light-emitting device 100 includes micro-LEDs having a surface area of ​​about 10,000 pm2 or less, about 4,000 pm2 or less, or about 2,500 pm2 or less, depending on the application, handling of the light-emitting device may be more difficult due to its small form factor.However, according to exemplary embodiments, since the light-emitting device 100 includes the protective layer 90 disposed between the connecting electrodes 20ce, 30ce, 40ce, and 50ce, handling of the light-emitting device 100 can be facilitated during subsequent processes such as transfer and packaging. In addition, the light-emitting structure can be protected by the protective layer 90 from external impacts, and light interference between adjacent light-emitting devices 100 can be prevented. The carrier substrate 11c is not particularly limited as long as the carrier substrate 11c stably mounts the light-emitting device 100 with the second adhesive layer 13. The second adhesive layer 13 may be a tape, but the inventive concepts are not limited thereto, as long as the second adhesive layer 13 stably fixes the light-emitting device 100 to the carrier substrate 11c, and the light-emitting device 100 is capable of being separated during subsequent processes. In some exemplary embodiments, the light-emitting device 100 of FIG. 13 may not be transferred to the separated carrier substrate 11c, but may be directly transferred to a circuit board 11p. The light-emitting device 100 may be mounted on the circuit board 11 p. According to an exemplary embodiment, the circuit board 11 p may include an upper circuit electrode 11 pa, a lower circuit electrode 11 pe, and a middle circuit electrode 11 pb that are electrically connected to each other. The upper circuit electrodes 11 pa may correspond to each of the first, second, third, and fourth connection electrodes 20 ce, 30 ce, 40 ce, and 50 ce, respectively. In some exemplary embodiments, because the upper circuit electrodes 11 pa are surface-treated by ENIG, and partially melt at an elevated temperature, electrical connection to the connection electrodes of the light-emitting device 100 may be facilitated. According to the illustrated exemplary embodiment, the light emitting devices 100 may be spaced apart from each other on the carrier substrate 11c at a desired pitch in consideration of a pitch (P, see FIG. 16B) of the upper circuit electrode 11pa of the circuit board 11p, which will be mounted in an end-use device, such as a display apparatus. According to an exemplary embodiment, the first, second, third, and fourth connection electrodes 20ce, 30ce, 40ce, and 50ce of the light-emitting device 100 may be bonded to the upper circuit electrodes 11pa of the circuit board 11p, respectively, by anisotropic conductive film (ACF) bonding, for example. When the light-emitting device 100 is bonded to the circuit board via the ACF bonding, which may be performed at a lower temperature than other bonding methods, the light-emitting device 100 may be prevented from being exposed to an elevated temperature during bonding. However, the inventive concepts are not limited to a specific bonding method. For example, in some exemplary embodiments, the light emitting devices 100 may be attached to the circuit board 11p using anisotropic conductive paste (ACP), solder, a ball grid array (BGA), or a micro bump that includes at least one of Cu and Sn.In this case, since the upper surfaces of the connecting electrodes 20ce, 30ce, 40ce and 50ce and the protection layer 90 are substantially flush with each other by a polishing process or the like, the adhesion of the light emitting device 100 to the anisotropic conductive film is increased and therefore a more stable structure can be formed while adhering to the circuit board 11p. Referring to FIG. 15A , a light-blocking layer 91 is formed between the light-emitting devices 100. According to an exemplary embodiment, the light-blocking layer 91 may block light by reflecting or absorbing light emitted by the light-emitting device 100. In an exemplary embodiment, the light-blocking layer 91 may be a black molding layer that absorbs and blocks light. The light-blocking layer 91 may be substantially flush with a top surface of the light-emitting device 100, i.e., a light-emitting surface. The light-blocking layer 91 may cover a side surface of the substrate 11 and may be flush with a top surface of the substrate 11. As such, the light-blocking layer 91 may prevent light from being emitted through the side surface of the substrate 11.Since the light-emitting surface is limited to the upper surface of the substrate 11 by the light-blocking layer 91, the light viewing angles of the first, second, and third light-emitting stacks 20, 30, and 40 can be substantially the same. Furthermore, the light-blocking layer 91, together with the protective layer 90 formed on the light-emitting device 100, provides additional protection to the light-emitting package by reinforcing its structure. In an exemplary embodiment, the light-blocking layer 91 may include an organic or inorganic polymer. In some exemplary embodiments, the light-blocking layer 91 may further include fillers such as silica or alumina. In some exemplary embodiments, the light-blocking layer 91 may include the same material as the shielding layer 90. The light-blocking layer 91 may be formed through various methods well known in the art, such as lamination, plating, and / or printing methods. For example, the light-blocking layer 91 may be formed by a vacuum lamination process, wherein a sheet of organic polymer is disposed over the light-emitting device 100 and subjected to a high temperature and high pressure in a vacuum, thereby providing a substantially flat upper surface of the light-emitting package, thereby improving light uniformity.The light-blocking layer 91 may be partially removed to expose the upper surface of the light-emitting device 100, i.e., the upper surface of the substrate 11, by a grinding process or a full-surface etching process. In some exemplary embodiments, the substrate 11 may be removed from the light emitting device 100 before the light blocking layer 91 is formed. In this case, the light blocking layer 91 may cover a side surface of the first conductive semiconductor layer 41 and expose a top surface of the first conductive semiconductor layer 41. Referring to FIG. 15B , a transparent layer 93 is formed covering the light-blocking layer 91 and the light-emitting devices 100. The transparent layer 93 transmits light emitted from the first, second, and third light-emitting stacks 20, 30, and 40. The transparent layer 93 may increase a viewing angle of the light emitted from the light-emitting device 100 by a light-guiding effect. For example, the viewing angle of the light emitted from the light-emitting device 100 may be in a range of about 110 degrees to about 120 degrees. A thickness of the transparent layer 93 may be adjusted to achieve the above viewing angle. In an exemplary embodiment, the transparent layer 93 may be formed by an insulating layer having a refractive index between that of the substrate 11 and that of air. In this way, it is possible to reduce light loss caused by total internal reflection at an interface between the substrate 11 and air. In particular, a difference between a refractive index of the transparent layer 93 and that of air may have a smaller value than a difference between a refractive index of the first conductive type semiconductor layer 41 and that of the substrate 11. The transparent layer 93 may be formed, for example, by S¡O2, silicone resin, epoxy, polyimide, SU8, spin glass (SOG), benzocyclobutene (BCB), or the like. The transparent layer 93 may be formed as a single layer, but the inventive concepts are not limited thereto, and it may be formed as a plurality of layers. Referring to FIGS. 16A and 16B, the light emitting device 100 disposed on the circuit board 11p may be cut into a desired configuration and formed as a light emitting package 110. FIG. 16B exemplarily illustrates the light emitting package 110 including four light emitting devices 100 (2x2) disposed on the circuit board 11p. However, the inventive concepts are not limited to a specific number of light emitting devices formed in the light emitting package 110. For example, in some exemplary embodiments, the light emitting package 110 may include one or more light emitting devices 100 formed on the circuit board 11p.Furthermore, the inventive concepts are not limited to a specific arrangement of one or more light-emitting devices 100 in the light-emitting package 110, and, for example, one or more light-emitting devices 100 in the light-emitting package 110 may be arranged in an nxm arrangement, where n and m refer to natural numbers. According to an exemplary embodiment, the circuit board 11p may include a scan line and a data line for independently driving each of the light-emitting devices 100 included in the light-emitting package 110. FIG. 17 is a schematic cross-sectional view illustrating a display apparatus according to an exemplary embodiment. Referring to FIG. 17, the display apparatus may include a display substrate 11 b and a light emitting package 110. The light emitting package 110 may be mounted on the display substrate 11 b of an end apparatus, such as a display apparatus. The display substrate 11 b may include target electrodes 11 s corresponding to the electrodes of the lower circuit 11 p e of the light emitting package 110, respectively. The display apparatus according to an exemplary embodiment may include a plurality of pixels, and each of the light emitting devices 100 may be arranged to correspond to each pixel. More specifically, each light emitting stack of the light emitting devices 100 according to an exemplary embodiment may correspond to each subpixel of a pixel.Since the light-emitting devices 100 include the light-emitting stacks 20, 30, and 40 that are stacked vertically, the number of devices to be transferred for each sub-pixel can be substantially reduced relative to conventional light-emitting devices to be transferred. Furthermore, since the surfaces of the connecting electrodes opposite each other have different lengths from each other, the connecting electrodes can be stably formed in the structure of the light-emitting stack to strengthen an internal structure thereof. Furthermore, since the light-emitting devices 100 according to some exemplary embodiments include a protection layer 90 between the connecting electrodes, the light-emitting devices 100 can be protected from external impact. In the illustrated exemplary embodiment, although the light emitting package 110 is described as being mounted on the display substrate 11b, in some exemplary embodiments, the manufacturing process of the light emitting package 110 may be omitted, and the light emitting devices 100 may be directly mounted on the display substrate 11b, and a light blocking layer 91 and a transparent layer 93 may be formed thereon. FIG. 18 is a schematic cross-sectional view illustrating a light emitting package 120 according to another exemplary embodiment. With reference to FIG. 18, the light emitting package 120 according to the illustrated exemplary embodiment is substantially similar to the light emitting package 110 described with reference to FIGS. 15A , 15B , 16A , and 16B , but a light emitting device 200 according to the illustrated exemplary embodiment does not include the substrate 11. The substrate 11 is removed from the light emitting device 100 and thus the first conductive semiconductor layer 41 is exposed. The light emitting device 200 emits light through the upper surface of the first conductive semiconductor layer 41, and thus the upper surface of the first conductive semiconductor layer 41 becomes a light emitting surface.The light-blocking layer 91 covers a side surface of the first conductive-type semiconductor layer 41 and exposes the top surface thereof, and the transparent layer 93 covers the light-blocking layer 91 and the first conductive-type semiconductor layers 41. FIG. 19 is a schematic cross-sectional view illustrating a light emitting package 130 according to another exemplary embodiment. With reference to FIG. 19, the light emitting package 130 according to the illustrated exemplary embodiment is substantially similar to the light emitting package 110 described with reference to FIGS. 15A, 15B, 16A and 16B, but a height HM of an upper surface of the light blocking layer 91 is smaller than a height HS of the light emitting surface of the substrate 11. Thus, at least a portion of the side surface of the substrate 11 is exposed without being covered by the light blocking layer 91, and the transparent layer 93 covers the upper surface of the substrate 11 and the exposed side surface thereof. Since light can be emitted outward through the exposed portion of the side surface of the substrate 11, the viewing angle of the light emitted from the light emitting device 100 can be further increased. In some exemplary embodiments, the upper surface of the light-blocking layer 91 may be arranged to expose at least a portion of the third light-emitting stack 40, and in this case, the loss of light emitted from the third light-emitting stack 40 by the light-blocking layer 91 may be reduced, thereby increasing the luminous intensity of the light emitted from the third light-emitting stack 40. For example, when the third light-emitting stack 40 emits green light, it is possible to increase the luminous intensity of the green light, and thus an RGB mixing ratio can be easily adjusted to a desired value. FIG. 20 is a schematic cross-sectional view illustrating a light emitting package 140 according to another exemplary embodiment. With reference to FIG. 20, the light-emitting package 140 according to the illustrated exemplary embodiment is substantially similar to the light-emitting package 120 described with reference to FIG. 18, but a height HM of an upper surface of the light-blocking layer 91 is less than a height HG of a light-emitting surface of the third light-emitting stack 40. As such, at least a portion of a side surface of the third light-emitting stack 40 is exposed without being covered by the light-blocking layer 91, and the transparent layer 93 covers an upper surface of the third light-emitting stack 40 and the exposed side surface thereof. Since the light can be emitted outwardly through the exposed portion of the side surface of the third light-emitting stack 40, the viewing angle of the light emitted from the light-emitting device 100 can be further increased. Furthermore, the loss of light emitted from the third light-emitting stack 40 by the light-blocking layer 91 can be reduced, and thus, the luminous intensity of the light emitted from the third light-emitting stack 40 can be increased. For example, when the third light-emitting stack 40 emits green light, it is possible to increase the luminous intensity of the green light, and thus, an RGB mixing ratio can be easily adjusted to a desired value. Meanwhile, to prevent an increase in the luminous intensity of the blue light, the height HM of the light-blocking layer 91 is greater than a height HB of the second light-emitting stack 30. In the above exemplary embodiments, the transparent layer 93 may cover the entire surface of the light-emitting devices 100 or 200. However, the inventive concepts are not limited thereto, and the transparent layer 93 may partially cover the light-emitting devices 100 or 200. This will be described with reference to FIG. 21. FIG. 21 is a schematic plan view illustrating a light emitting package 150 according to another exemplary embodiment. Referring to FIG. 21, the light-emitting package 150 according to the illustrated exemplary embodiment has a shape in which a transparent layer 93 is patterned. A light-blocking layer 91 is disposed between the light-emitting devices 100, and the transparent layer 93 is disposed over the light-emitting devices 100 and over the light-blocking layer 91. The transparent layer 93 is designed to partially cover the light-emitting devices 100. In particular, as illustrated, the transparent layer 93 may have a mesh shape including a transparent layer 93a extending in the lateral direction and a transparent layer 93b extending in the longitudinal direction. The transparent layer 93a in the lateral direction traverses the light-emitting devices 100, and the transparent layer 93b in the longitudinal direction is disposed over the light-blocking layer 91. A viewing angle of the light emitted from the light emitting device 100 in the lateral direction can be increased to a greater extent than that of the light emitted from the light emitting device 100 in the longitudinal direction by the transparent layer 93a extending in the lateral direction. In general, since the human eye is more sensitive to a variation of light in the lateral direction of a display image than in the longitudinal direction thereof, it is possible to selectively reduce the variation of light in the lateral direction perceived by the human eye by increasing the viewing angle in the lateral direction. Meanwhile, the transparent layer 93 may be patterned after being formed on the light-blocking layer 91, but the transparent layer 93 may be bonded to the light-emitting devices 100 and the light-blocking layer 91 by manufacturing a mesh-shaped sheet. In the illustrated exemplary embodiment, the transparent layer 93 is described as being mesh-shaped, but the inventive concepts are not limited thereto. For example, in some exemplary embodiments, the transparent layer 93 may be arranged to intersect an upper surface of the light-emitting device 100 in the lateral direction, and thus, light variation in the lateral direction may be reduced. In the illustrated exemplary embodiment, the light emitting package 150 is described as including the light emitting devices 100, but in some exemplary embodiments, the light emitting package may include light emitting devices 200 instead of the light emitting devices 100. Although several exemplary embodiments of the light-emitting packages 110, 120, 130, 140, and 150 have been described above, in some exemplary embodiments, the light-emitting devices 100 or 200 may be mounted directly on the display substrate without a light-emitting package forming process, and the light-blocking layer 91 and the transparent layer 93 may be formed on the display substrate. Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broadest scope of the appended claims and to various obvious modifications and equivalent arrangements that would be apparent to one of ordinary skill in the art.

Claims

1. A display apparatus, comprising a display substrate; a plurality of light-emitting devices disposed on the display substrate; a light-blocking layer disposed between the light-emitting devices; and a transparent layer covering the light-emitting devices and the light-blocking layer, characterized in that at least one of the light-emitting devices 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, and wherein the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit.

2. The display apparatus of claim 1, characterized in that the light-blocking layer is configured to block light by absorbing light emitted from the light-emitting device, and the transparent layer is configured to transmit light emitted from the light-emitting device.

3. The display apparatus of claim 2, characterized in that the light-blocking layer comprises a black molding layer.

4. The display apparatus of claim 1, characterized in that the first, second, and third LED subunits are configured to emit red light, blue light, and green light, respectively.

5. The display apparatus of claim 1, characterized in that the first LED subunit includes a first light-emitting cell; the second LED subunit includes a second light-emitting cell; the third LED subunit includes a third light-emitting cell; and each of the first, second, and third light-emitting cells includes a first conductive-type semiconductor layer, an active layer, and a second conductive-type semiconductor layer.

6. The display apparatus of claim 5, characterized in that the transparent layer partially covers the light-emitting devices.

7. The display apparatus of claim 6, characterized in that the transparent layer is arranged to pass through the light-emitting devices in one direction.

8. The display apparatus of claim 7, characterized in that the transparent layer is mesh-shaped and includes a first transparent layer extending in a lateral direction and a second transparent layer extending in a longitudinal direction; the first transparent layer passes through the light-emitting devices; and the second transparent layer is disposed over the light-blocking layer in a region between the light-emitting devices.

9. The display apparatus of claim 5, characterized in that an upper surface of the light-blocking layer is positioned at the same elevation or lower than that of the light-emitting device.

10. The display apparatus of claim 9, characterized in that: the light-emitting device further includes a substrate disposed on the third LED subunit; and a difference in refractive indices between the transparent layer and air is less than a difference in refractive indices between the substrate and the first conductive-type semiconductor of the third light-emitting stack.

11. The display apparatus of claim 8, characterized in that the light-emitting device further includes a substrate disposed over the third LED subunit; and the upper surface of the light-blocking layer is positioned at a lower elevation than an upper surface of the substrate to expose at least a portion of a side surface of the substrate.

12. The display apparatus of claim 9, characterized in that the light-blocking layer is positioned at a lower elevation than an upper surface of the third light-emitting stack to expose at least a portion of a side surface of the third light-emitting stack.

13. The display apparatus of claim 5, characterized in that the light-emitting device further includes: 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.

14. The display apparatus of claim 13, characterized in that the light-emitting device further includes: 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 commonly electrically connected to the first, second, and third LED subunits.

15. The display apparatus of claim 14, further comprising a circuit board interposed between the display substrate and the light-emitting device, wherein: the first, second, third, and fourth connecting electrodes are attached to the circuit board; and the light-blocking layer is arranged on the circuit board.

16. The display apparatus of claim 14, characterized in that: the first connecting electrode, the second connecting electrode, and the third connecting electrode are electrically connected to the second conductive-type semiconductor layers of the first light-emitting cell, the second light-emitting cell, and the third light-emitting cell, respectively; and the fourth connecting electrode is commonly electrically connected to the first conductive-type semiconductor layers of the first, second, and third light-emitting cell.

17. The display apparatus of claim 15, characterized in that: the light-emitting device further includes: first, second, and third lower contact electrodes that are in contact with the second conductive-type semiconductor layers of the first, second, and third light-emitting cells, respectively; and a first insulating layer having first, second, and third contact holes that partially expose the first, second, and third lower contact electrodes; the first insulating layer has sub-contact holes arranged in the first conductive-type semiconductor layers of the first, second, and third light-emitting cells; and the sub-contact holes are separated from each other.

18. The display apparatus of claim 17, characterized in that: the light-emitting device further includes first, second, and third pads overlapping the first, second, and third contact holes and a fourth pad overlapping the sub-contact holes; and the first, second, third, and fourth connection electrodes are electrically connected to the first, second, third, and fourth pads, respectively.

19. A display apparatus, comprising: a display substrate; a plurality of light-emitting devices disposed on the display substrate; a black molding layer disposed between the light-emitting devices to block the light emitted by the light-emitting devices; and a transparent layer that at least partially covers the light-emitting devices and is configured to transmit the light emitted by the light-emitting devices, characterized in that at least one of the light-emitting devices 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, and wherein the third LED subunit is disposed closer to an upper surface of the light-emitting device than the first LED subunit.

20. The display apparatus of claim 19, characterized in that an upper surface of the black molding layer is positioned at the same elevation or lower than those of the light-emitting devices.

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