Light emitting device, display apparatus including the same, and method of manufacturing the same

Abstract

A light-emitting device, a display apparatus including the light-emitting device, and a method of manufacturing the light-emitting device are provided. The light-emitting device includes: a light-emitting unit including a first electrode and a second electrode disposed on an upper surface and separated from each other; an extension layer in which the light-emitting unit is embedded and the extension layer has a width greater than the width of the light-emitting unit; and a first electrode pad and a second electrode pad disposed on the upper surface of the extension layer and separated from each other and electrically connected to the first electrode and the second electrode, respectively.

Description

Technical Field

[0001] The apparatus and methods consistent with the example embodiments relate to a light-emitting device, a display device including the light-emitting device, and a method of manufacturing the display device. Background Technology

[0002] Compared to light sources based on related technologies, light-emitting devices (LEDs) are considered to be the next generation of light sources with advantages such as long lifespan, low power consumption, fast response speed, and environmental friendliness, and are used in various products such as lighting devices and backlighting for display devices. In particular, group III nitride-based LEDs such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), and indium aluminum gallium nitride (InAlGaN) are used as light-emitting devices for outputting light. Summary of the Invention

[0003] One or more example embodiments provide a light-emitting device having a chip coverage extending beyond the light-emitting unit and a method of manufacturing the same.

[0004] In addition, one or more example embodiments provide a display device including an extended light-emitting device and a method of manufacturing the same.

[0005] According to one aspect of this disclosure, a light-emitting device includes: a first electrode and a second electrode provided on the upper surface of a light-emitting unit; an extension layer in which the light-emitting unit is embedded and the extension layer has a width greater than that of the light-emitting unit; a first electrode pad and a second electrode pad provided on the upper surface of the extension layer and electrically connected to the first electrode and the second electrode, respectively, wherein the spacing between the first electrode pad and the second electrode pad is greater than the spacing between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap with the first electrode pad and the second electrode pad in the thickness direction of the light-emitting device.

[0006] The first electrode pad is provided on the central axis of the extension layer, and the second electrode pad surrounds the first electrode pad.

[0007] The second electrode pad may not overlap with the first and second electrodes in the thickness direction of the light-emitting device.

[0008] At least one of the first electrode pads and the second electrode pads can be symmetrical about the central axis of the light-emitting device.

[0009] At least one of the first electrode pads and the second electrode pads is linearly or rotationally symmetrical about the central axis of the light-emitting device.

[0010] The spacing between the first electrode pad and the second electrode pad is 1.5 times or greater than the spacing between the first electrode and the second electrode.

[0011] The width of at least one of the first electrode pad and the second electrode pad is greater than the width of either the first electrode or the second electrode.

[0012] The central axis of the light-emitting device may not match the central axis of the light-emitting unit.

[0013] The light-emitting unit has a rotationally asymmetric shape relative to the central axis of the light-emitting unit.

[0014] The light-emitting unit has a polygonal cross-sectional shape.

[0015] The first electrode and the second electrode are spaced apart from each other, and the central axis of the light-emitting unit is located between them.

[0016] The extension layer includes a first region disposed at the center of the light-emitting device and a second region surrounding the first region, and the light-emitting unit is embedded in the first region.

[0017] In addition, the light-emitting unit can be embedded in the first region.

[0018] Furthermore, the thickness of the first region can be different from the thickness of the second region.

[0019] Furthermore, the thickness of the first region can be greater than the thickness of the second region.

[0020] In addition, the light-emitting device may also include: a first through electrode that penetrates the extension layer and has one end in contact with the first electrode and the other end in contact with the first electrode pad; and a second through electrode that penetrates the extension layer and has one end in contact with the second electrode and the other end in contact with the second electrode pad.

[0021] Furthermore, at least one of the first through electrode and the second through electrode can be bent once or more.

[0022] Furthermore, a portion of the second through electrode can overlap with the second electrode pad in the thickness direction of the light-emitting device.

[0023] In addition, the light-emitting unit may include multiple sub-light-emitting units that emit light of different wavelengths, and each of the first electrode pad and the second electrode pad may include multiple sub-electrode pads that are electrically connected to the multiple sub-light-emitting units respectively.

[0024] According to another aspect of this disclosure, a display device may include: a display layer including a plurality of light-emitting devices; and a driving layer including a plurality of transistors electrically connected to the plurality of light-emitting devices to drive the plurality of light-emitting devices, wherein at least one of the plurality of light-emitting devices may include: a light-emitting unit including a first electrode and a second electrode provided on an upper surface of the at least one of the plurality of light-emitting devices; an extension layer in which the light-emitting unit is embedded and the extension layer has a width greater than the width of the light-emitting unit; a first electrode pad and a second electrode pad provided on the upper surface of the extension layer and electrically connected to the first electrode and the second electrode, respectively, wherein the spacing between the first electrode pad and the second electrode pad is greater than the spacing between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap the first electrode pad and the second electrode pad in the thickness direction of the at least one of the plurality of light-emitting devices.

[0025] The display layer may also include a partition wall provided on the driving layer and having a plurality of holes, the light-emitting unit being provided in one of the plurality of holes, and the edge region of the extension layer being disposed on the upper surface of the partition wall.

[0026] Furthermore, the light-emitting units can be arranged to be separated from the driving layer space.

[0027] According to another aspect of this disclosure, a display device may include: a light-emitting unit including a plurality of electrodes; an extension layer covering a top surface of the light-emitting unit and the plurality of electrodes of the light-emitting unit; a first electrode pad and a second electrode pad provided on the top surface of the extension layer, wherein the first electrode pad is disposed directly above the light-emitting unit, and the second electrode pad has an annular shape to surround the first electrode pad; and a plurality of through electrodes passing through the extension layer to connect the first electrode pad and the second electrode pad to the plurality of electrodes of the light-emitting unit, respectively, wherein the first electrode pad and the second electrode pad are spaced apart from the light-emitting unit in the vertical direction of the display device, and in the horizontal direction of the display device, the spacing between the first electrode pad and the second electrode pad is greater than the spacing between the plurality of electrodes of the light-emitting unit.

[0028] According to another aspect of this disclosure, a method of manufacturing a light-emitting device may include: preparing a substrate including a plurality of grooves; transferring each of a plurality of light-emitting units into the plurality of grooves such that a first electrode and a second electrode of each of the plurality of light-emitting units have spaced-apart surfaces thereon facing outward from the grooves; forming a first through electrode, a second through electrode, and an extension layer on the surface of each of the plurality of light-emitting units, the first through electrode and the second through electrode being in contact with the first electrode and the second electrode, respectively; forming a first electrode pad and a second electrode pad on the extension layer, the first electrode pad and the second electrode pad being in contact with the first through electrode and the second through electrode, respectively, wherein the spacing between the first electrode pad and the second electrode pad is greater than the spacing between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap the first electrode pad and the second electrode pad in the thickness direction of the light-emitting device.

[0029] In addition, the first electrode pad can be located on the central axis of the extension layer, and the second electrode pad can surround the first electrode pad.

[0030] Furthermore, the second electrode pad may not overlap with the first and second electrodes in the thickness direction of the light-emitting device.

[0031] Furthermore, the width of at least one of the first electrode pad and the second electrode pad may be greater than the width of at least one of the first electrode and the second electrode.

[0032] Furthermore, the central axis of the light-emitting device may not match the central axis of the light-emitting unit. Attached Figure Description

[0033] The above and other aspects, features and advantages of certain embodiments of this disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, wherein:

[0034] Figure 1A This is a cross-sectional view showing a light-emitting device according to an example embodiment; Figure 1B This shows what it looks like when viewed from above. Figure 1A Light-emitting devices.

[0035] Figures 2A to 2D This is a reference diagram illustrating a method for manufacturing a light-emitting device according to an example embodiment;

[0036] Figures 3A to 3E This is a reference diagram illustrating a method for manufacturing a display device using a light-emitting device according to an example embodiment;

[0037] Figures 4A to 4E This is a reference diagram illustrating a process for manufacturing a display device using a light-emitting device according to another example embodiment;

[0038] Figure 5A light-emitting device according to another exemplary embodiment is shown;

[0039] Figures 6A to 6C This is a reference diagram illustrating a method for manufacturing a light-emitting device according to another exemplary embodiment;

[0040] Figure 7 A light-emitting device according to another exemplary embodiment is shown;

[0041] Figure 8 This is a plan view of a light-emitting device according to another example embodiment;

[0042] Figure 9 This is a plan view of a light-emitting device according to another example embodiment;

[0043] Figure 10 This is a plan view of a light-emitting device according to another example embodiment;

[0044] Figure 11A This is a plan view of a light-emitting device including multiple light-emitting units according to an example embodiment;

[0045] Figure 11B This illustrates an example implementation. Figure 11A A cross-sectional view of the light-emitting device;

[0046] Figure 12 This is a cross-sectional view illustrating a schematic structure of a display transfer structure including a light-emitting device according to an example embodiment;

[0047] Figure 13 A display transfer structure according to another example embodiment is shown;

[0048] Figure 14 The illustration shows the transfer of a light-emitting device provided in a display transfer structure to a TFT substrate according to an example embodiment;

[0049] Figure 15 This is a cross-sectional view illustrating a schematic structure of a display transfer structure according to another exemplary embodiment;

[0050] Figure 16 This is a cross-sectional view illustrating a schematic structure of a display transfer structure according to another exemplary embodiment;

[0051] Figure 17 This is a cross-sectional view illustrating a schematic structure of a display transfer structure according to another exemplary embodiment; and

[0052] Figure 18 This is a cross-sectional view showing a schematic structure of a display device according to an example embodiment. Detailed Implementation

[0053] The exemplary embodiments are described in more detail below with reference to the accompanying drawings.

[0054] In the following description, the same reference numerals are used for the same elements, even in different figures. Specific details defined in the description, such as particular structures and elements, are provided to aid in a comprehensive understanding of the exemplary embodiments. However, it will be apparent that the exemplary embodiments can be practiced without those specific definitions. Furthermore, well-known functions or structures are not described in detail, as such detail would obscure the description.

[0055] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. When expressions such as “at least one of…” follow a list of elements, they modify the entire list of elements, not individual elements within the list.

[0056] In the following description, embodiments will be illustrated with reference to the accompanying drawings. The described embodiments are merely exemplary, and various modifications to the embodiments are possible. Throughout the drawings, the same reference numerals refer to the same elements. For ease of explanation and clarity, the thickness or dimensions of each layer shown in the figures may be exaggerated.

[0057] In a layered structure, when a constituent element is positioned "above" or "on top of" another constituent element, the constituent element may be located directly on the other constituent element or in a non-contact manner above the other constituent element.

[0058] Terms such as “first” and “second” are used herein only to describe various constituent elements, but the constituent elements are not limited by these terms. Such terms are only used to distinguish one constituent element from another. These terms do not limit the materials or structures of the constituent elements to be different from each other.

[0059] Expressions used in the singular include plural expressions unless they have a distinct meaning in the context. It will be further understood that the terms “comprising” and / or “including” as used herein indicate the presence of the stated feature or component, but do not preclude the presence or addition of one or more other features or components.

[0060] Furthermore, terms such as “…part,” “…unit,” “…module,” and “…block” used in the specification may refer to a unit that performs at least one function or operation, and the unit may be implemented by hardware, software, or a combination of hardware and software.

[0061] The terms “a,” “one,” “the,” and similar designations used in the context of describing this disclosure shall be interpreted to cover both the singular and the plural.

[0062] Furthermore, the steps of all methods described herein may be performed in any suitable order unless otherwise stated herein or clearly contradicted by the context. This disclosure is not limited to the order of the described steps. Additionally, any and all examples or language (e.g., “for example”) provided herein are intended only to better illustrate this disclosure and do not constitute a limitation on the scope of this disclosure unless otherwise stated.

[0063] Figure 1A This is a cross-sectional view of a light-emitting device 100 according to an example embodiment. Figure 1B This shows what it looks like when viewed from above. Figure 1A The light-emitting device 100.

[0064] like Figure 1A As shown, the light-emitting device 100 may include a light-emitting unit 110 and an extension layer 120. The light-emitting unit 110 is embedded in the extension layer 120, and the extension layer 120 has a width w2 that is larger than the width w1 of the light-emitting unit 110. A plurality of electrode pads 130 are arranged on the upper surface of the extension layer 120 and spaced apart from each other and electrically connected to the light-emitting unit 110. The central axis X1 of the extension layer 120 may not match the central axis X2 of the light-emitting unit 110.

[0065] The light-emitting unit 110 may include a light-emitting diode based on inorganic materials, and the light-emitting unit 110 may emit light of a specific wavelength depending on the material it contains. The light-emitting unit 110 may be miniature. For example, the width w1 of the light-emitting unit 110 may be about 100 μm or less.

[0066] The light-emitting unit 110 may include multiple semiconductor layers. For example, the light-emitting unit 110 may include a first semiconductor layer, an active layer, and a second semiconductor layer. The first semiconductor layer may include, for example, an n-type semiconductor. However, this disclosure is not limited thereto; in some cases, the first semiconductor layer may include a p-type semiconductor. The active layer may be disposed on the first semiconductor layer and may generate light when electrons and holes combine with each other, and may have a multiple quantum well (MQW) structure or a single quantum well (SQW) structure. The second semiconductor layer may be provided on the active layer and may include a semiconductor layer having a different type of semiconductor layer than the first semiconductor layer.

[0067] The light-emitting unit 110 may further include a plurality of electrodes disposed on one surface of the light-emitting unit 110 and spaced apart from each other. For example, a first electrode 112 and a second electrode 114 may be disposed on the same surface of the light-emitting unit 110 and spaced apart from each other. The first electrode 112 may be electrically connected to a first semiconductor layer, and the second electrode 114 may be electrically connected to a second semiconductor layer. The first electrode 112 and the second electrode 114 may not be disposed on the central axis X2 of the light-emitting unit 110. For example, the first electrode 112 and the second electrode 114 may be arranged to be spaced apart from each other, with the central axis X2 of the light-emitting unit 110 located therebetween.

[0068] The first electrode 112 and the second electrode 114 may include conductive materials. For example, the first electrode 112 and the second electrode 114 may include transparent conductive materials. The first electrode 112 and the second electrode 114 may include metals (such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr or alloys thereof), conductive oxides (such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO) or indium tin zinc oxide (ITZO)), conductive polymers (such as poly(3,4-ethylenedioxythiophene) (PEDOT)), etc.

[0069] The width w1 of the light-emitting unit 110 can be approximately 5 μm or larger and approximately 100 μm or smaller. The light-emitting unit 110 can be fabricated, for example, by growing the light-emitting unit 110 on a wafer such as sapphire or silicon and then separating the light-emitting unit 110 using a laser or etching solution. When the light-emitting unit 110 is too small, for example, when the width w1 of the light-emitting unit 110 is less than 5 μm, it is difficult to fabricate a light-emitting unit 110 of good quality due to surface current leakage. Furthermore, when using small light-emitting units to manufacture display devices, there is an increased problem of electrical connection failures.

[0070] When the width w1 of the light-emitting unit 110 is relatively large, for example, when the width w1 of the light-emitting unit 110 is about 100 μm or greater, it is possible to manufacture a light-emitting unit 110 with good quality, but the number of light-emitting units manufactured from a single wafer is reduced. This can increase the cost of manufacturing a device including the light-emitting unit 110 (e.g., a display device).

[0071] Therefore, it is necessary to reduce electrical connection failures while minimizing or avoiding cost increases. To this end, the light-emitting device 100 according to an example embodiment may further include an extension layer 120, which includes light-emitting units 110 and has a width greater than the width w1 of the light-emitting units 110.

[0072] The maximum width w2 of the extension layer 120 can be about 1.5 times or more the width w1 of the light-emitting unit 110. As the width w2 of the extension layer 120 increases, the width of the light-emitting device 100 can also increase. However, since the light-emitting device 100 functions as a sub-pixel of the display, it may be difficult to achieve a high resolution for the display as the size of the light-emitting device 100 increases. Therefore, the maximum width w2 of the extension layer 120 can be about 500 μm or less.

[0073] The extension layer 120 may include a first region 122 disposed in the central region or recessed region and a second region 124 surrounding the side surface of the first region 122. The first region 122 may have a first thickness d1, and the second region 124 may have a second thickness d2. For example, the first thickness d1 may be greater than the second thickness d2. The light-emitting unit 110 may be included in the lower region of the first region 122, at least a portion of the side surface and upper surface of the light-emitting unit 110 may contact the first region 122, and the lower surface of the light-emitting unit 110 may be exposed to the outside.

[0074] The extension layer 120 may include an insulating material. The extension layer 120 may include an organic insulating film (propylene or silicon-based polymer) or an inorganic insulating film (SiO2, SiN, Al2O3, or TiO2), but this disclosure is not limited thereto. The extension layer 120 may have a multilayer structure comprising various insulating materials having different dielectric constants.

[0075] The light-emitting device 100 may further include electrode pads 130 disposed on the upper surface of the extension layer 120 and spaced apart from each other. The electrode pads 130 may include a first electrode pad 132 electrically connected to a first electrode 112 and a second electrode pad 134 electrically connected to a second electrode 114. Furthermore, the light-emitting device 100 may also include a plurality of through electrodes 140 passing through the extension layer 120. For example, the through electrodes 140 may include a first through electrode 142 and a second through electrode 144, the first through electrode 142 passing through the extension layer 120 and having one end in contact with the first electrode 112 and the other end in contact with the first electrode pad 132, and the second through electrode 144 passing through the extension layer 120 and having one end in contact with the second electrode 114 and the other end in contact with the second electrode pad 134.

[0076] Each of the first electrode pad 132, the second electrode pad 134, the first through electrode 142, and the second through electrode 144 may include a conductive material. At least one of the first electrode pad 132, the second electrode pad 134, the first through electrode 142, and the second through electrode 144 may include a transparent conductive material. At least one of the first electrode pad 132, the second electrode pad 134, the first through electrode 142, and the second through electrode 144 may include a metal (such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or alloys thereof), a conductive oxide (such as ITO, IZO, ZnO, or ITZO), a conductive polymer (such as PEDOT), etc.

[0077] At least one of the first through electrode 142 and the second through electrode 144 may include a region that bends once or more, or a region that slopes in a direction toward the edge of the light-emitting device 100. Therefore, the spacing between the first electrode pad 132 and the second electrode pad 134 can be greater than the spacing between the first electrode 112 and the second electrode 114. For example, the spacing between the first electrode pad 132 and the second electrode pad 134 can be 1.5 times or greater than the spacing between the first electrode 112 and the second electrode 114. At least one of the first electrode 112 and the second electrode 114 may not overlap with the first electrode pad 132 and the second electrode pad 134 in the direction along the thickness d1 of the light-emitting device 100. Since the first through electrode 142 and the second through electrode 144 are added to the light-emitting device 100 and have electrical connections with the first electrode pad 132 and the second electrode pad 134, and also because the second through electrode 144 partially overlaps the second electrode pad 134 in the direction along the thickness d1 of the light-emitting device 100, the spacing between the connector electrodes of the light-emitting device 100 can be increased. The width of at least one of the first electrode pad 132 and the second electrode pad 134 may be greater than the width of either the first electrode 112 or the second electrode 114. Therefore, the first electrode pad 132 and the second electrode pad 134 can reduce defects caused by process errors during electrode connection.

[0078] At least one of the first electrode pad 132 and the second electrode pad 134 can be symmetrical with respect to the central axis X1 of the upper surface of the extension layer 120, or can be in a symmetrical position with respect to the central axis X1. At least one of the first electrode pad 132 or the second electrode pad 134 can be rotationally or linearly symmetrical with respect to the central axis X1 of the upper surface of the extension layer 120. For example, the first electrode pad 132 can be arranged on the central axis X1 of the upper surface of the extension layer 120, while the second electrode pad 134 can be arranged at a certain distance from the central axis X1 of the upper surface of the extension layer 120. Since the first electrode pad 132 and the second electrode pad 134 are symmetrically arranged with respect to the central axis X1 of the upper surface of the extension layer 120, the transfer direction can be disregarded when the light-emitting device 100 according to an example embodiment is transferred to another substrate, etc.

[0079] The extension layer 120 can serve as a base layer for forming the first electrode pad 132 and the second electrode pad 134 thereon, or as a collector for collecting light emitted from the light-emitting device 100. For example, light emitted in the direction of the side surface of the light-emitting unit 110 can be totally reflected by the side surface of the first region 122 to be emitted through the front surface of the light-emitting device 100. The light concentration can vary depending on the width of the first region 122. Furthermore, the second region 124 of the extension layer 120 can act as a guide when transferring the light-emitting device 100 to another substrate.

[0080] Figures 2A to 2D This is a reference diagram illustrating a method for manufacturing a light-emitting device 100 according to an example embodiment.

[0081] like Figure 2A As shown, a substrate 210 can be prepared. The substrate 210 can be a single body or a single mold structure including a plurality of grooves H1. The substrate 210 can include, for example, organic materials, inorganic materials (such as silicon, glass, sapphire, and polymers) and / or metals, and can be manufactured by methods such as photoresist patterning, etching, molding, etc., but this disclosure is not limited thereto. When the light-emitting unit 110 is transferred to the substrate 210, the grooves H1 can guide the transfer of the light-emitting unit 110.

[0082] The grooves H1 may each have a cross-sectional area larger than that of the light-emitting unit 110, so as to accommodate the light-emitting unit 110 within each groove H1. The grooves H1 may have a shape similar to the cross-section of the light-emitting unit 110 (e.g., a circular cross-section or a polygonal cross-section). The grooves H1 may have a depth less than or greater than the thickness of the light-emitting unit 110, for example, less than twice the thickness of the light-emitting unit 110 or a depth in the range of about 0.5 to 1.5 times.

[0083] like Figure 2B As shown, multiple light-emitting units 110 can be transferred to substrate 210. The light-emitting units 110 can be supplied to substrate 210 while contained in a suspension. Methods for supplying the light-emitting units contained in the suspension can include various methods, such as spraying, droplet-by-drop distribution, liquid spraying (e.g., printing), and methods of flowing the suspension to substrate 210. During the transfer process, the light-emitting units 110 can be positioned in the groove H1 by means of surface energy difference, complementary shapes between the groove H1 and the light-emitting units 110, etc. The light-emitting units 110 can be positioned in the groove H1 such that the surfaces of the first electrode and the second electrode spaced apart thereon face outwards from the groove.

[0084] The light-emitting unit 110 is transferred via a fluid self-assembly method. However, this disclosure is not limited thereto, and the light-emitting unit 110 according to an example embodiment can be transferred by various methods such as pick-and-place methods.

[0085] like Figure 2C As shown, a first through electrode 142, a second through electrode 144, and an extension layer 120 can be formed on a substrate 210 to which the light-emitting unit 110 is transferred. The first through electrode 142, the second through electrode 144, and the extension layer 120 can be formed by alternately depositing conductive and insulating materials using a mask. The lower ends of the first through electrode 142 and the second through electrode 144 can contact the first electrode 112 and the second electrode 114, respectively. When forming the first through electrode 142, the second through electrode 144, and the extension layer 120, the first through electrode 142 and the second through electrode 144 can be formed such that the spacing between them gradually increases. At least one of the first through electrode 142 and the second through electrode 144 can be bent once or more, and at least one of the first through electrode 142 and the second through electrode 144 can extend further away from the light-emitting unit 110 in a direction toward the edge of the light-emitting unit 110.

[0086] like Figure 2DAs shown, a first electrode pad 132 and a second electrode pad 134 can be formed on the upper surface of the extension layer 120. The first electrode pad 132 can contact the first through electrode 142, and the second electrode pad 134 can contact the second through electrode 144. Since the first electrode pad 132 is arranged on the central axis X1 of the upper surface of the extension layer 120, and the second electrode pad 134 is arranged at the edge of the extension layer 120, the spacing between the first electrode pad 132 and the second electrode pad 134 can be greater than the spacing between the first electrode 112 and the second electrode 114. At least one of the first electrode 112 and the second electrode 114 may not overlap with the first electrode pad 132 and the second electrode pad 134 in the thickness direction of the extension layer 120. The width of at least one of the first electrode pad 132 or the second electrode pad 134 can be greater than the width of either the first electrode 112 or the second electrode 114. Therefore, by using the first electrode pad 132 and the second electrode pad 134, process errors during the electrode connection process can be reduced.

[0087] Figures 3A to 3E This is a reference diagram illustrating a method of manufacturing a display device using a light-emitting device 100 according to an example embodiment.

[0088] refer to Figure 3A The target substrate 310 can be aligned above the substrate 210 on which the light-emitting device 100 is formed. The target substrate 310 may include a substrate 312 and a driving layer 314. The substrate 312 may include an insulating material such as glass, organic polymer, crystal, etc. In addition, the substrate 312 may include a flexible material that can be bent or folded, and may have a single-layer structure or a multi-layer structure. The driving layer 314 may include transistors, electrode patterns, etc. for driving the light-emitting device 100. The electrode pads of the light-emitting device 100 may be arranged to face the electrode patterns formed on the target substrate 310.

[0089] like Figure 3B As shown, the light-emitting device 100 can be transferred to the target substrate 310. For example, the light-emitting device 100 can be transferred to the target substrate 310 by a bonding method. After the substrate 210 and the target substrate 310 are aligned with each other, the light-emitting device 100 can be bonded to the target substrate 310 by using hot pressing, ultrasonic waves, or light (such as laser, ultraviolet (UV) light). For example, when hot pressing is applied between the electrode pads of the light-emitting device 100 and the electrode pattern of the target substrate 310, a eutectic bond can be formed between the electrode pads of the light-emitting device 100 and the electrode pattern of the target substrate 310 to bond the electrode pads of the light-emitting device 100 and the electrode pattern of the target substrate 310.

[0090] After the light-emitting device 100 is transferred to the target substrate 310, the substrate 210 can be removed. For example... Figure 3C As shown, the position of the target substrate 310 can be changed so that the light-emitting device 100 is positioned above it.

[0091] like Figure 3D As shown, a planarization layer 320 can be formed on the light-emitting device 100. The planarization layer 320 can have a flat upper surface and cover the light-emitting device 100. The planarization layer 320 can mitigate steps caused by constituent elements located below the planarization layer 320 and prevent oxygen, moisture, etc., from penetrating into the light-emitting device 100. The planarization layer 320 may include an insulating material. The planarization layer 320 may include an organic insulating film (e.g., a propylene or silicon-based polymer film) or an inorganic insulating film (including SiO2, SiN, Al2O3, or TiO2), but this disclosure is not limited thereto. The planarization layer 320 may have a multilayer structure including various insulating materials having different dielectric constants.

[0092] like Figure 3E As shown, the color conversion layer 330 can be formed on the planarization layer 320. When the light-emitting device 100 emits light of the same wavelength, the color conversion layer 330 can include first to third color conversion patterns 331, 333, and 335 that convert the light generated by the light-emitting device 100 into light of a specific wavelength. Each of the first to third color conversion patterns 331, 333, and 335 can correspond to each sub-pixel. For example, the first color conversion pattern 331 can correspond to the first sub-pixel SP1, the second color conversion pattern 333 can correspond to the second sub-pixel SP2, and the third color conversion pattern 334 can correspond to the third sub-pixel SP3.

[0093] Although Figure 3E The illustration shows that the light-emitting device 100 emits light of the same wavelength, but this disclosure is not limited thereto. When the light-emitting device 100 emits different light rays (e.g., red, blue, and green light) as sub-pixels, a color conversion layer 330 may not be formed.

[0094] Figures 4A to 4E This is a reference diagram illustrating a process for manufacturing a display device using a light-emitting device 100 according to another example embodiment.

[0095] like Figure 4A As shown, the driving layer 414 can be formed on the substrate 412. The driving layer 414 may include a TFT, a first electrode pattern EL1, a capacitor, etc.

[0096] like Figure 4BAs shown, a partition wall 420 with a hole H2 can be formed on the driving layer 414. The partition wall 420 may include a polymer layer 422 and a metal layer 424. The metal layer 424 may be electrically connected to the first electrode pattern EL1 of the driving layer 414 via a hole h formed in the polymer layer 422. The substrate 412, the driving layer 414, and the partition wall 420 can form a transfer substrate.

[0097] like Figure 4C As shown, the light-emitting device 100 can be transferred into the interior of the aperture H2. The light-emitting device 100 can be transferred by methods such as fluid self-assembly, pick-and-place methods, etc.

[0098] The width of aperture H2 can be smaller than the maximum width of light-emitting device 100, i.e., the maximum width of extension layer 120. Therefore, when light-emitting device 100 is moved into the interior of aperture H2, the light-emitting unit 110 replacing light-emitting device 100 is fully inserted into aperture H2, and extension layer 120 of light-emitting device 100 can be arranged to extend to the exterior of aperture H2. As described above, since the maximum width of extension layer 120 is greater than the width of aperture H2, light-emitting device 100 can be stably moved into aperture H2.

[0099] When the light-emitting device 100 is reversed and transferred into the interior of the aperture H2, the light-emitting device 100 is mistakenly transferred. Since the extension layer 120 and the light-emitting unit 110 protrude too much from the aperture H2, the mistakenly transferred light-emitting device 100 is easily removed.

[0100] Furthermore, when the thickness d1 of the protruding portion of the light-emitting device 100 (i.e., a portion of the first region 122) is less than the thickness of the aperture H2, the light-emitting device 100 can be arranged to be separated from the bottom surface of the aperture H2 when it is moved into the interior of the aperture H2. Since the heat radiated from the light-emitting unit 110 is dissipated through the separation space, this separation space can serve a heat dissipation function.

[0101] like Figure 4D As shown, an insulating layer 430 can be formed covering at least a portion of the light-emitting device 100 and the partition wall 420, and a second electrode pattern EL2 can be formed to electrically connect the electrode pads 130 of the light-emitting device 100 to the driving layer 414. The second electrode pattern EL2 can be electrically connected to the first electrode pattern EL1 of the driving layer 414 through the metal layer 424 of the partition wall 420. The insulating layer 430 can prevent oxygen, moisture, etc. from penetrating into the light-emitting device 100.

[0102] like Figure 4E As shown, a planarization layer 440 can be formed on the insulating layer 430 and the second electrode pattern EL2. A color conversion layer can then be further formed.

[0103] Figure 5A light-emitting device 100a according to another exemplary embodiment is shown. When compared... Figure 1A and Figure 5 In this case, the extension layer 120a of the light-emitting device 100a may include different materials. For example, the first region of the extension layer 120a may include a first material 520, and the second region 124 of the extension layer 120a may include the first material 520 and a second material 513. The first material 520 may include an insulating material. The first material 520 may be a material that is compatible with... Figure 1A The extension layer 120 is made of essentially the same material. The second material 513 can be an insulating material, but the invention is not limited thereto. For example, the second material 513 can be various materials, such as silicon, photoresist, etc.

[0104] because Figure 5 The lower and side surfaces of the light-emitting device 100a are flat, so optical structures such as reflective films can be further arranged on the lower and side surfaces. Therefore, the light extraction efficiency can be improved.

[0105] In addition, Figure 5 In the light-emitting device 100a, the light-emitting unit 110 is protected by the first material 520 and the second material 513. Therefore, the light-emitting device 100a can be more efficient than... Figure 1A The light-emitting device 100 absorbs shocks better. Therefore, Figure 5 The light-emitting unit 110 of the light-emitting device 100a can be protected by physical forces.

[0106] Figures 6A to 6C This is a reference diagram illustrating a method for manufacturing a light-emitting device 100a according to another exemplary embodiment.

[0107] like Figure 6A As shown, the light-emitting unit 110 can be transferred onto a substrate 510 having a recess H3. The substrate 510 can be a multilayer structure. For example, the substrate 510 may include a base layer 511, a sacrificial layer 512 disposed on the base layer 511, and a partition wall 513 having holes. The base layer 511, the sacrificial layer 512, and the partition wall 513 can be formed on a silicon-on-insulator (SOI) substrate. However, this disclosure is not limited thereto.

[0108] The groove H3 may have a cross-sectional area larger than that of the light-emitting unit 110 to accommodate the light-emitting unit 110. The groove H3 may have a shape similar to the cross-section of the light-emitting unit 110 (e.g., a circular cross-section or a polygonal cross-section). The groove H3 may have a depth less than or greater than the thickness of the light-emitting unit 110, for example, less than twice the thickness of the light-emitting unit 110 or in the range of about 0.5 to 1.5 times the thickness of the light-emitting unit 110.

[0109] The light-emitting unit 110 can be transferred by various methods such as fluid self-assembly, pick-up and placement.

[0110] like Figure 6B As shown, a first through electrode 142, a second through electrode 144, and a first material 520 can be formed on a substrate 510 to which the light-emitting unit 110 is transferred. The first through electrode 142, the second through electrode 144, and the first material 520 can be formed by alternately depositing conductive and insulating materials using a mask. One end of the first through electrode 142 can be formed to contact the first electrode 112, and one end of the second through electrode 144 can be formed to contact the second electrode 114. Due to the formation of the first material 520, the first through electrode 142 and the second through electrode 144 can be formed such that the mounting of the first through electrode 142 and the second through electrode 144 provides the effect of increasing the spacing between the connector electrodes of the display device. At least one of the first through electrode 142 and the second through electrode 144 can be bent once or more, and at least one of the first through electrode 142 and the second through electrode 144 can extend further away from the light-emitting unit 110 in a direction toward the edge of the light-emitting unit 110.

[0111] First electrode pad 132 and second electrode pad 134 can be formed on the upper surface of the first material 520. First electrode pad 132 can contact the first through electrode 142, and second electrode pad 134 can contact the second through electrode 144. Since the first electrode pad 132 can be arranged on the central axis of the first material 520 and the second electrode pad 134 can be arranged at the edge of the first material 520, the spacing between the first electrode pad 132 and the second electrode pad 134 can be greater than the spacing between the first electrode 112 and the second electrode 114. Furthermore, the width of at least one of the first electrode pad 132 and the second electrode pad 134 can be greater than the width of either the first electrode 112 or the second electrode 114.

[0112] like Figure 6C As shown, the light-emitting device 100a can be separated from the substrate 511 by removing the sacrificial layer 512. The light-emitting device 100a and the substrate 511 can be separated from each other by applying heat to the sacrificial layer 512. After the light-emitting device 100a is transferred to the target substrate 310, the substrate 511 can be removed.

[0113] Figure 7 A light-emitting device 100b according to another example embodiment is shown. When compared... Figure 1A and Figure 7 At that time, Figure 7In the light-emitting device 100b, the thickness of the first region 122a of the extended layer 120b overlapping in the thickness direction of the light-emitting device 100b can be less than the thickness of the second region 124a of the extended layer 120b overlapping in the thickness direction of the light-emitting device 100b. Therefore, the lower space of the light-emitting unit 110 can perform heat dissipation. The light-emitting device 100b can be fabricated by using a protruding region instead of a recess in the substrate. The surface of the protruding region can be more hydrophilic than the surface of the recess. The lower surface of the light-emitting unit 110 can be placed on the protruding region, and the extended layer 120b and through electrodes can be formed thereon. The first electrode pad 132 and the second electrode pad 134 can be formed on the surface of the extended layer 120b.

[0114] although Figure 1B The cross-sectional shapes of the light-emitting unit 110 and the extension layer 120 are shown to be different from each other, but this disclosure is not limited thereto. The cross-sectional shapes of the light-emitting unit 110 and the extension layer 120 may be the same, and the first electrode pad 132 and the second electrode pad 134 may not have a shape that is symmetrical with respect to the central axis X1 of the upper surface of the extension layer 120.

[0115] Figures 8 to 10 Examples of light-emitting devices with various cross-sections are shown. For example... Figure 8 As shown, the cross-sectional shapes of the light-emitting unit 110a and the extension layer 120b can be different from each other. For example, the light-emitting unit 110a can have a rotationally asymmetric cross-section. The cross-section of the light-emitting unit 100a can have a rotationally asymmetric polygonal shape. When the light-emitting unit 110a is transferred to the substrate to form the extension layer 120b after manufacturing, the size of the light-emitting unit 110a is small, so the light-emitting unit 110a may be difficult to transfer onto the substrate. When the cross-section of the light-emitting unit 110a has a rotationally asymmetric shape, the transfer of the light-emitting unit 110a will be much easier if the recess of the substrate has the same shape as the rotationally asymmetric cross-section.

[0116] The cross-section of the extension layer 120b can be rotationally symmetrical, and the first electrode pad 132 and the second electrode pad 134 can have a shape that is rotationally symmetrical with respect to the central axis of the light-emitting device 100c. In the case of electronic devices using the light-emitting device 100c, such as display devices, the rotationally symmetrical structure can facilitate processes such as electrode connections.

[0117] Or, such as Figure 9As shown, the extension layer 120c can be rotated asymmetrically with respect to the central axis of its upper surface, similar to the light-emitting unit 110b. The extension layer 120c and the light-emitting unit 110b can have the same cross-sectional shape but different dimensions. This improves the transfer efficiency of the light-emitting device 100d when it is transferred to the target substrate. The first electrode pad 132a and the second electrode pad 134a may not be arranged on the central axis of the upper surface of the extension layer 120c, and can be arranged symmetrically with respect to the central axis of the upper surface of the extension layer 120c. For example, the first electrode pad 132a and the second electrode pad 134a can be arranged symmetrically with respect to the centerline of the upper surface of the extension layer 120. By increasing the spacing between the first electrode pad 132a and the second electrode pad 134a, poor connections can be reduced.

[0118] Or, such as Figure 10 As shown, the extension layer 120d and the light-emitting unit 110c can both have rotationally asymmetrical shapes relative to the central axis of the upper surface of the extension layer 120d. The cross-sections of the extension layer 120d and the light-emitting unit 110c can have the same shape but different dimensions. When the light-emitting device 100e is transferred to the target substrate, the transfer efficiency of the light-emitting device 100e can be improved. The first electrode pad 132b and the second electrode pad 134b can not be arranged on the central axis of the upper surface of the extension layer 120d, but can be arranged in a position symmetrical with respect to the central axis of the upper surface of the extension layer 120d. For example, the first electrode pad 132b and the second electrode pad 134b can be arranged rotationally symmetrically with respect to the central axis of the upper surface of the extension layer 120d. By increasing the spacing between the first electrode pad 132b and the second electrode pad 134b, poor connections can be reduced.

[0119] Figure 11A and Figure 11B A light-emitting device 100f comprising a plurality of light-emitting units is shown according to another exemplary embodiment. In the light-emitting device 100f, the plurality of light-emitting units 110d, 110e, and 110f may be included in an extension layer 120e. For example, the light-emitting device 100f may include first to third light-emitting units 110d, 110e, and 110f arranged separately from each other. The first to third light-emitting units 110d, 110e, and 110f may emit light of different wavelengths. For example, the first light-emitting unit 110d may emit red light, the second light-emitting unit 110e may emit green light, and the third light-emitting unit 110f may emit blue light. Therefore, one light-emitting device 100f may operate as a pixel.

[0120] The cross-sectional shapes of the light-emitting units 110d, 110e, and 110f can differ from each other depending on the wavelength. Therefore, the light-emitting units 110d, 110e, and 110f can be transferred to a substrate for each wavelength.

[0121] A first set of electrode pads 130a electrically connected to the first light-emitting unit 110d, a second set of electrode pads 130b electrically connected to the second light-emitting unit 110e, and a third set of electrode pads 130c electrically connected to the third light-emitting unit 110f can be disposed on the upper surface of the extension layer 120e. Each of the first to third sets of electrode pads 130a, 130b, and 130c may include a first electrode pad and a second electrode pad electrically connected to the first electrode and the second electrode of each of the light-emitting units 110d, 110e, and 110f.

[0122] A first group of through electrodes 140a, a second group of through electrodes 140b, and a third group of through electrodes 140c can be arranged in the extension layer 120e. Each of the first group of through electrodes 140a has one end contacting the first light-emitting unit 110d and the other end contacting each electrode pad 130a. Each of the second group of through electrodes 140b has one end contacting the second light-emitting unit 110e and the other end contacting each electrode pad 130b. Each of the third group of through electrodes 140c has one end contacting the third light-emitting unit 110f and the other end contacting each electrode pad 130c. Each of the first to third groups of through electrodes 140a, 140b, and 140c may include a first through electrode and a second through electrode electrically connected to the first electrode and the second electrode of each light-emitting unit 110d, 110e, and 110f, respectively. Since one light-emitting device 100f becomes one pixel, a display device can be easily manufactured.

[0123] Figure 12 This is a cross-sectional view showing a schematic structure of a display transfer structure 600 including a light-emitting device 100 according to an example embodiment.

[0124] The display transfer structure 600 may include a transfer substrate 610, which includes a plurality of grooves 620 and light-emitting devices 100 disposed in each groove 620.

[0125] The transfer substrate 610 may include, for example, organic materials, inorganic materials (such as silicon, glass, or polymers), etc. The transfer substrate 610 may be formed as a single layer or multiple layers.

[0126] Each recess 620 may have a cross-sectional area larger than that of the light-emitting device 100 to accommodate the light-emitting device 100. The cross-sectional dimension of each recess 620 may be larger than the cross-sectional dimension of the light-emitting device 100 but less than twice the cross-sectional dimension of the light-emitting device 100. Therefore, one light-emitting device 100 may be arranged in each recess 620. Each recess 620 may have a shape similar to the cross-section of the light-emitting device 100 (e.g., a circular cross-section or a polygonal cross-section).

[0127] The thickness of each groove 620 can be similar to the maximum thickness of the light-emitting device 100. For example, the thickness of each groove 620 can be about 0.5 times or more, or about 1.5 times or less, the thickness of the light-emitting device 100.

[0128] The upper surface of the transfer substrate may have a finer structure or chemical properties than the surface in the recess 620. For example, the upper surface of the transfer substrate may have a relatively large surface roughness, a relatively small area in contact with the surface of the light-emitting device, or be relatively hydrophobic. Simultaneously, such property differences can help align the electrodes of the light-emitting device 100 in a specific direction (i.e., outward in the recess 620), reduce the amount of light-emitting devices 100 retained and not transferred to the recess 620, or allow the remaining devices to be easily separated from the transfer substrate 610 during cleaning operations.

[0129] Figure 13 A display transfer structure 601 according to another example embodiment is shown. When compared... Figure 12 and Figure 13 hour, Figure 13 The display transfer structure 601 may also include an additional coating 630 on the outer surface of the transfer substrate 610. The surface of the coating 630 may have physical and chemical properties different from those of the surface in the groove 620.

[0130] The coating 630 may include a metal, such as Ag, Au, Pt, Ni, Cr, and / or Al, and the type of metal or process conditions may be selected to increase the surface energy difference with the transfer substrate 610. The coating 630 may also be implemented by further bonding a polymer to the metal layer or by coating only a polymer. Additional patterning or surface treatment of the coating may increase surface roughness or reduce the contact area with the light-emitting device.

[0131] The aforementioned display transfer structures 600 and 601 can be applied to display devices using the light-emitting device 100. The light-emitting device 100 provided in the aforementioned display transfer structures 600 and 601 may include multiple LED chips for emitting red (R), green (G), and blue (B) light, or may consist of multiple LED chips emitting only blue (B) light. The display transfer structures 600 and 601 can be applied to display devices in which the light-emitting device 100 operates as a single pixel, such as an RGB self-emissive micro-LED television. In this case, the display transfer structures 600 and 601 can be used as a single unit as a display device, or the light-emitting device 100 provided in the display transfer structures 600 and 601 can be transferred to a TFT substrate via bonding methods such as eutectic bonding or ACF bonding.

[0132] Figure 14 The illustration shows the transfer of a light-emitting device 100 provided in a display transfer structure 600 to a TFT substrate TS according to an example embodiment.

[0133] like Figure 14 As shown, the display transfer structure 610 can be used as a transfer mold for transferring the light-emitting device 100 to another location. The light-emitting device 100 can be bonded and transferred thereon to a TFT substrate TS having driving circuitry (such as a TFT) for driving the light-emitting device 100. Since the light-emitting device 100 is aligned in each groove 620 of the transfer substrate 610, the light-emitting device 100 can be well transferred to a predetermined position on the TFT substrate TS. After the light-emitting device 100 is bonded and transferred to the TFT substrate TS, the display device can be completed by additional processes. The manufacturing yield of the display device can be improved by using the display transfer structure 600 according to an example embodiment.

[0134] The display transfer structure can be directly applied to display devices. Figures 15 to 17 Display transfer structures 602, 603 and 604 are shown, with additional structures provided for direct application to the display device.

[0135] Figure 15 This is a cross-sectional view showing a schematic structure of a display transfer structure 602 according to another exemplary embodiment.

[0136] The display transfer structure 602 of this embodiment may have wherein, Figure 12 The display transfer structure 600 further provides the shape of an additional material layer.

[0137] The display transfer structure 602 may further include an insulating layer 640 formed in the recess 620 and circuit elements 651 and 652 connected to the first electrode pad 132 and the second electrode pad 134 of the light-emitting device 100. The circuit elements 651 and 652 may form part of a driving circuit for driving the light-emitting device 100.

[0138] Figure 16 This is a cross-sectional view showing a schematic structure of a display transfer structure 603 according to another exemplary embodiment.

[0139] The display transfer structure 603 of this embodiment differs from the display transfer structure 602 in that it uses a circuit board 623 having a driving circuit for driving the light-emitting device 100 as the transfer board. The circuit board 623 may include circuit elements including driving transistors, switching transistors, capacitors, etc. In order to align the light-emitting device 100 to a regular position, after forming a groove 620 directly on the circuit board 623, the light-emitting device 100 is aligned in the groove 620 using a wet alignment method. Therefore, additional processes can be reduced and the display transfer structure 603 can be used as a display device.

[0140] Figure 17 This is a cross-sectional view showing a schematic structure of a display transfer structure 604 according to another exemplary embodiment.

[0141] The display transfer structure 604 of this embodiment may include a circuit board 625 disposed below the transfer substrate 624. The circuit board 625 may include circuit elements including driving transistors, switching transistors, capacitors, etc., and the circuit elements of the circuit board 625 may be electrically connected to the light-emitting device 100 through conductive paths penetrating the transfer substrate 624.

[0142] Figure 18 This is a cross-sectional view showing a schematic structure of a display device 700 according to an example embodiment.

[0143] The display device 700 may include a display transfer structure 604 in which light-emitting devices 100 are disposed in each recess 620, and a color conversion layer 720 disposed on the display transfer structure 604.

[0144] Although Figure 17 The display transfer structure 604 shown is an example, but this disclosure is not limited to this and can be modified as follows. Figure 15 Display transfer structure 602, Figure 16 The display transfer structure 603 or any form modified therefrom.

[0145] A passivation layer 710, including insulating material, can be disposed on the display transfer structure 604, and a color conversion layer 720 can be disposed on the passivation layer 710.

[0146] The color conversion layer 720 may include a first color conversion layer 720B for converting light from the light-emitting device 100 into a first color light, a second color conversion layer 720G for converting the light into a second color light, and a third color conversion layer 720R for converting the light into a third color light. The first color light may be, for example, blue light, the second color light may be, for example, green light, and the third color light may be, for example, red light. The first color conversion layer 720B, the second color conversion layer 720G, and the third color conversion layer 720R may be arranged separately from each other and have partition walls therebetween, and face the light-emitting device 100.

[0147] A capping layer 730 can be disposed on the color conversion layer 720, and a color filter layer 740 can be disposed on the capping layer 730. The color filter layer 740 may include a first color filter 740B, a second color filter 740G, and a third color filter 740R, separated from each other and with a black matrix 741 between them. The first color filter 740B, the second color filter 740G, and the third color filter 740R can be arranged to face the first color conversion layer 720B, the second color conversion layer 720G, and the third color conversion layer 720R, respectively. The first color filter 740B, the second color filter 740G, and the third color filter 740R can transmit blue light, green light, and red light, respectively, and can absorb other colors of light. The color filter layer 740 can be omitted.

[0148] A display device comprising any one of the aforementioned light-emitting devices 100, 100a, 100b, 100c, 100d, 100e, and 100f can be used in a variety of electronic devices. For example, this display device can be applied to televisions, laptops, mobile phones, smartphones, tablets (PDs), portable multimedia players (PMPs), personal digital assistants (PDAs), navigation devices, smartwatches, head-mounted displays, signature devices, etc.

[0149] The foregoing exemplary embodiments are merely illustrative and should not be construed as limiting. This teaching can be readily applied to other types of devices. Furthermore, the description of the exemplary embodiments is intended to be illustrative and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.

[0150] This application is based on and claims priority to Korean Patent Application No. 10-2021-0141878, filed on October 22, 2021, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A light emitting device comprising: a light emitting unit including a first electrode and a second electrode provided on an upper surface of the light emitting unit; an extension layer in which the light emitting unit is embedded and which has a width greater than a width of the light emitting unit; and a first electrode pad and a second electrode pad provided on an upper surface of the extension layer and electrically connected to the first electrode and the second electrode, respectively, wherein a separation between the first electrode pad and the second electrode pad is greater than a separation between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap the first electrode pad and the second electrode pad in a thickness direction of the light emitting device, wherein the first electrode pad is on a center axis of the extension layer, the second electrode pad is spaced apart from and surrounds the first electrode pad, and is symmetric about the center axis of the extension layer. 2.The light emitting device of claim 1, wherein the second electrode pad does not overlap the first electrode and the second electrode in the thickness direction of the light emitting device. 3.The light emitting device of claim 1, wherein at least one of the first electrode pad and the second electrode pad is linearly or rotationally symmetric about the center axis of the extension layer. 4.The light emitting device of claim 1, wherein the separation between the first electrode pad and the second electrode pad is 1.5 times or more of the separation between the first electrode and the second electrode. 5.The light emitting device of claim 1, wherein a width of at least one of the first electrode pad and the second electrode pad is greater than a width of any one of the first electrode and the second electrode. 6.The light emitting device of claim 1, wherein the center axis of the extension layer does not match a center axis of the light emitting unit. 7.The light emitting device of claim 1, wherein the light emitting unit has a rotationally asymmetric shape with respect to a center axis of the light emitting unit. 8.The light emitting device of claim 7, wherein the light emitting unit has a polygonal cross-sectional shape. 9.The light emitting device of claim 1, wherein the first electrode and the second electrode are spaced apart from each other and a center axis of the light emitting unit is located therebetween. 10.The light emitting device of claim 1, wherein the extension layer includes a first region disposed at a center of the light emitting device and a second region surrounding the first region, and wherein the light emitting unit is embedded in the first region. 11.The light emitting device of claim 10, wherein a thickness of the first region is greater than a thickness of the second region. 12.The light emitting device of claim 1, further comprising: a first through electrode penetrating the extension layer and having one end in contact with the first electrode and the other end in contact with the first electrode pad; and a second through electrode penetrating the extension layer and having one end in contact with the second electrode and the other end in contact with the second electrode pad. ​ a second through electrode penetrating the extension layer and having one end in contact with the second electrode and the other end in contact with the second electrode pad.

13. The light emitting device according to claim 12, wherein at least one of the first through electrode and the second through electrode is bent one or more times.

14. The light emitting device according to claim 12, wherein a partial area of the second through electrode overlaps with the second electrode pad in the thickness direction of the light emitting device.

15. The light emitting device according to claim 1, wherein the light emitting cell includes a plurality of sub light emitting cells configured to emit light of different wavelengths, and each of the first electrode pad and the second electrode pad includes a plurality of sub electrode pads electrically connected to the plurality of sub light emitting cells, respectively.

16. A display device comprising: a display layer including a plurality of light emitting devices; and a driver layer including a plurality of transistors electrically connected to the plurality of light emitting devices to drive the plurality of light emitting devices, wherein at least one of the plurality of light emitting devices includes: a light emitting cell including a first electrode and a second electrode provided on an upper surface of the light emitting cell; an extension layer in which the light emitting cell is embedded and which has a width greater than a width of the light emitting cell; a first electrode pad and a second electrode pad provided on an upper surface of the extension layer and electrically connected to the first electrode and the second electrode, respectively, and wherein a spacing between the first electrode pad and the second electrode pad is greater than a spacing between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap with the first electrode pad and the second electrode pad in a thickness direction of the at least one of the plurality of light emitting devices, wherein the first electrode pad is on a center axis of the extension layer, the second electrode pad is spaced apart from and surrounds the first electrode pad, and is symmetrical about the center axis of the extension layer.

17. The display device according to claim 16, wherein the display layer further includes a partition wall provided on the driver layer and having a plurality of holes, the light emitting cell is provided in one of the plurality of holes, and an edge region of the extension layer is disposed on an upper surface of the partition wall.

18. A display device comprising: a light emitting cell including a plurality of electrodes; an extension layer covering a top surface of the light emitting cell and the plurality of electrodes of the light emitting cell; a first electrode pad and a second electrode pad provided on a top surface of the extension layer, wherein the first electrode pad is disposed directly above the light emitting cell, the second electrode pad has a circular ring shape to surround the first electrode pad; and a plurality of through electrodes passing through the extension layer to connect the first electrode pad and the second electrode pad to the plurality of electrodes of the light emitting cell, respectively, wherein the first electrode pad and the second electrode pad are spaced apart from the light emitting unit in a vertical direction of the display device, and in a horizontal direction of the display device, a spacing between the first electrode pad and the second electrode pad is greater than a spacing between the plurality of electrodes of the light emitting unit, wherein the first electrode pad is on a center axis of the extension layer, the second electrode pad is spaced apart from and surrounds the first electrode pad, and is symmetric about the center axis of the extension layer. 19.A method of manufacturing a light emitting device, comprising: preparing a substrate including a plurality of recesses; transferring each of a plurality of light emitting units to the plurality of recesses such that a first electrode and a second electrode of each of the plurality of light emitting units face a surface on which the first electrode and the second electrode are spaced apart outward of the recess; forming a first through electrode, a second through electrode, and an extension layer on the surface of each of the plurality of light emitting units, the first through electrode and the second through electrode being in contact with the first electrode and the second electrode, respectively; and forming a first electrode pad and a second electrode pad on the extension layer, the first electrode pad and the second electrode pad being in contact with the first through electrode and the second through electrode, respectively, wherein a spacing between the first electrode pad and the second electrode pad is greater than a spacing between the first electrode and the second electrode, and at least one of the first electrode and the second electrode does not completely overlap the first electrode pad and the second electrode pad in a thickness direction of the light emitting device, wherein the first electrode pad is on a center axis of the extension layer, the second electrode pad is spaced apart from and surrounds the first electrode pad, and is symmetric about the center axis of the extension layer. 20.The method of claim 19, wherein the second electrode pad does not overlap the first electrode and the second electrode in the thickness direction of the light emitting device. 21.The method of claim 19, wherein a width of at least one of the first electrode pad and the second electrode pad is greater than a width of any one of the first electrode and the second electrode. 22.The method of claim 19, wherein the center axis of the extension layer does not match a center axis of the light emitting unit.

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