LED unit for display and display device having the same

Abstract

To provide a light emitting device.SOLUTION: A light emitting device includes: first, second, and third LED sub-units; and electrode pads disposed on the first LED sub-unit, electrically connected to the LED sub-units, and including a common electrode pad electrically connected to each of the LED sub-units, and first, second, and third electrode pads connected to a respective one of the LED sub-units. The common electrode pad, the second electrode pad, and the third electrode pad are electrically connected to the second LED sub-unit and the third LED sub-unit through holes that pass through the first LED sub-unit. The first, second, and third LED sub-units are configured to be independently driven, and light generated in the first LED sub-unit is configured to be emitted to the outside through the second and third LED sub-units. Light generated in the second LED sub-unit is configured to be emitted to the outside through the third LED sub-unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Exemplary embodiments of the present invention generally relate to display devices, and in particular to a display device having a light emitting diode (LED) unit pixel, a light emitting device for a display, and a display device, as well as a light emitting device for a display having a stacked structure of multiple LEDs and a display device having the same. [Background technology]

[0002] Light-emitting diodes (LEDs) have been used as inorganic light sources in a variety of fields, such as display devices, vehicle lamps, and general lighting. Due to their advantages of long life, low power consumption, and fast response speed, LEDs are rapidly replacing conventional light sources.

[0003] Meanwhile, light emitting diodes (LEDs) in related technology fields have been mainly used as backlight sources in display devices. However, micro LED displays have recently been developed as next-generation displays that directly realize images using light emitting diodes.

[0004] Generally, a display device realizes various colors by using a mixture of blue, green, and red colors. The display device includes a plurality of pixels for realizing various color images, and each pixel includes blue, green, and red sub-pixels. The color of a particular pixel is determined by the colors of the sub-pixels, and an image is realized by combining these pixels.

[0005] In the case of a micro LED display, the micro LEDs corresponding to each sub-pixel are arranged on a two-dimensional plane, which requires a large number of micro LEDs to be arranged on a single substrate. However, the micro LEDs are 10,000 μm 2The micro LEDs have a very small size with a surface area of ​​1000 um, which causes various problems: In particular, it is difficult to handle light emitting diodes with a small size, and it is difficult to mount hundreds of thousands or even millions of light emitting diodes on a display panel, and it is difficult to replace defective LEDs among the mounted micro LEDs with good LEDs.

[0006] In addition, since the subpixels are arranged on a two-dimensional plane, the area occupied by one pixel including the blue, green, and red subpixels increases relatively, so that in order to arrange the subpixels within the limited area, it is necessary to reduce the area of ​​each subpixel, which may result in a decrease in brightness due to the reduction in the light-emitting area.

[0007] The information disclosed in this Background section is intended merely to provide background understanding of the inventive concepts and, as such, may include information that does not constitute prior art. Summary of the Invention [Problem to be solved by the invention]

[0008] Light emitting diodes and displays using the same constructed in accordance with the principles and exemplary embodiments of the present invention can increase the light emitting area of ​​each subpixel without increasing the pixel area.

[0009] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments provide high reliability due to a stable LED structure and simplified manufacturing process in which a single via can connect to one or more semiconductor layers of each LED stack.

[0010] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles of the present invention and some exemplary embodiments provide pixels that can be manufactured simultaneously to avoid the cumbersome process of individually packaging pixels.

[0011] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles and some exemplary embodiments of the present invention can be driven in an active matrix manner.

[0012] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles and exemplary embodiments of the present invention can reduce packaging process time.

[0013] Displays using light emitting diodes and light emitting diodes, e.g., micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments can prevent optical interference between the LED stacks by arranging the first, second, and third LED stacks on top of each other to emit light having decreasing wavelengths, e.g., the first, second, and third LED stacks can emit red light, green light, and blue light, respectively.

[0014] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments can suppress the generation of secondary light between LED stacks by not arranging color filters between LED stacks, which are typically formed between LED stacks to prevent the generation of secondary light due to light emitted from adjacent LED stacks.

[0015] Additional features of the inventive concepts will be set forth in the description which follows, and in part will be obvious from such description, or may be learned by practicing the inventive concepts. [Means for solving the problem]

[0016] A display device according to an exemplary embodiment includes a thin film transistor (TFT) substrate, a first LED subunit arranged on the TFT substrate, a second LED subunit arranged on the first LED subunit, a third LED subunit arranged on the second LED subunit, electrode pads arranged between the TFT substrate and the first LED subunit, and connectors connecting the first, second, and third LED subunits to respective ones of the electrode pads, wherein the first LED subunit, the second LED subunit, and the third LED subunit are configured to be driven independently, and light generated from the first LED subunit is configured to be emitted outside the display device by passing through the second LED subunit and the third LED subunit, and light generated from the second LED subunit is configured to be emitted outside the display device by passing through the third LED subunit.

[0017] The first, second and third LED subunits may include a first LED stack, a second LED stack and a third LED stack, respectively, and the first, second and third LED stacks are configured to emit red light, green light and blue light, respectively.

[0018] The display device may include a first reflective electrode disposed between the TFT substrate and the first LED subunit and in contact with a lower surface of the first LED subunit, and the connector may include a first lower connector connecting the first reflective electrode to a first electrode pad among the electrode pads.

[0019] The connector may additionally include a first upper connector that connects the upper surface of the first LED subunit to a second electrode pad of the electrode pads.

[0020] The display device may additionally include a second transparent electrode interposed between the first LED subunit and the second LED subunit and in ohmic contact with a lower surface of the second LED subunit, and a third transparent electrode interposed between the second LED subunit and the third LED subunit and in ohmic contact with a lower surface of the third LED subunit, and the connector may additionally include a second lower connector connecting the second transparent electrode to a first electrode pad among the electrode pads, a second upper connector connecting an upper surface of the second LED subunit to a third electrode pad among the electrode pads, a third lower connector connecting the third transparent electrode to the first electrode pad among the electrode pads, and a third upper connector connecting an upper surface of the third LED subunit to a fourth electrode pad among the electrode pads.

[0021] The first bottom connector is connected to the top surface of the first reflective electrode, the second bottom connector is connected to the top surface of the second transparent electrode, and the third bottom connector is connected to the top surface of the third transparent electrode.

[0022] The first upper connector may be connected to an upper surface of the first LED subunit, the second upper connector may be connected to an upper surface of the second LED subunit, and the third upper connector may be connected to an upper surface of the third LED subunit, and at least one of the upper connectors may be substantially annular.

[0023] The connector may additionally include intermediate connectors that connect the second upper connector and the third upper connector to a third electrode pad and a fourth electrode pad, respectively, among the electrode pads.

[0024] Each connector can pass through one or more of the first, second and third LED subunits.

[0025] The first lower connector, the second lower connector, and the third lower connector are connected to a first electrode pad among the electrode pads, and the first upper connector, the second upper connector, and the third upper connector are connected to different electrode pads among the electrode pads, respectively.

[0026] The first lower connector, the second lower connector, and the third lower connector are stacked vertically on one another, and the first upper connector, the second upper connector, and the third upper connector are separable from one another vertically and laterally.

[0027] The display device may additionally include a second transparent electrode interposed between the first LED subunit and the second LED subunit and in ohmic contact with the lower surface of the second LED subunit, and a third transparent electrode interposed between the second LED subunit and the third LED subunit and in ohmic contact with the lower surface of the third LED subunit, and the connector may further include a second lower connector connecting the second transparent electrode to a third electrode pad among the electrode pads, a second upper connector connecting an upper surface of the second LED subunit to a second electrode pad among the electrode pads, a third lower connector connecting the third transparent electrode to a fourth electrode pad among the electrode pads, and a third upper connector connecting an upper surface of the third LED subunit to the second electrode pad among the electrode pads, and the first lower connector, the second lower connector, and the third lower connector are separated from each other and connected to the first, third, and fourth electrode pads among the electrode pads, respectively, and the first upper connector, the second upper connector, and the third upper connector are electrically connected to the second electrode pad among the electrode pads.

[0028] The first lower connector, the second lower connector, and the third lower connector are vertically and laterally separable from one another, and the first upper connector, the second upper connector, and the third upper connector are stacked vertically.

[0029] The display device may additionally include a first color filter interposed between the first LED subunit and the second LED subunit and configured to transmit light generated from the first LED subunit and reflect light generated from the second LED subunit, and a second color filter interposed between the second LED subunit and the third LED subunit and configured to transmit light generated from the first and second LED subunits and reflect light generated from the third LED subunit.

[0030] The display device may additionally include a first bonding layer interposed between the TFT substrate and the first LED subunit, a second bonding layer interposed between the first LED subunit and the second LED subunit, and a third bonding layer interposed between the second LED subunit and the third LED subunit, wherein the second bonding layer is configured to transmit light generated from the first LED subunit, and the third bonding layer is configured to transmit light generated from the first and second LED subunits.

[0031] The display device is configured to be driven by an active matrix method.

[0032] The third lower connector and the third upper connector may be exposed by the third LED subunit in plan view.

[0033] The first reflective electrode is disposed between the first LED subunit and the electrode pad.

[0034] The first, second and third LED subunits are approximately 10,000 μm 2 The micro LEDs may have a surface area of ​​less than 100 nm.

[0035] The first LED subunit is configured to emit one of red, green, and blue light, the second LED subunit is configured to emit one of red, green, and blue light that is different from the light emitted from the first LED subunit, and the third LED subunit is configured to emit one of red, green, and blue light that is different from the light emitted from the first and second LED subunits.

[0036] A light emitting device according to an exemplary embodiment includes: a first LED subunit; a second LED subunit disposed adjacent to the first LED subunit; a third LED subunit disposed adjacent to the second LED subunit; and electrode pads disposed on the first LED subunit and electrically connected to the first, second, and third LED subunits, the electrode pads including a common electrode pad electrically connected to each of the first, second, and third LED subunits, and first, second, and third electrode pads connected to respective ones of the first, second, and third LED subunits; The common electrode pad, the second electrode pad and the third electrode pad are electrically connected to the second LED subunit and the third LED subunit via holes penetrating the first LED subunit, the first LED subunit, the second LED subunit and the third LED subunit are configured to be driven independently, light generated in the first LED subunit is configured to be emitted outside the light-emitting device via the second LED subunit and the third LED subunit, and light generated in the second LED subunit is configured to be emitted outside the light-emitting device via the third LED subunit.

[0037] The first, second and third LED subunits may include a first LED stack, a second LED stack and a third LED stack, respectively, and the first, second and third LED stacks are configured to emit red light, green light and blue light, respectively.

[0038] The light emitting device may further include a first reflective electrode disposed between the electrode pad and the first LED subunit and in ohmic contact with the first LED subunit, and the common electrode pad is connected to the first reflective electrode.

[0039] The first reflective electrode may include an ohmic contact layer in ohmic contact with the top surface of the first LED subunit, and a reflective layer covering the ohmic contact layer.

[0040] The first reflective electrode may have a hollow portion provided by a substantially annular member, and the common electrode pad may pass through the hollow portion of the substantially annular member.

[0041] The light-emitting device may additionally include a second transparent electrode interposed between the second LED subunit and the third LED subunit and in ohmic contact with the lower surface of the second LED subunit, and a third transparent electrode in ohmic contact with the upper surface of the third LED subunit, and the common electrode pad is electrically connected to the second transparent electrode and the third transparent electrode.

[0042] The common electrode pad is connected to the top surface of the second transparent electrode and the top surface of the third transparent electrode.

[0043] Each of the first LED subunit and the third LED subunit may include a first conductive type semiconductor layer and a second conductive type semiconductor layer disposed on a partial region of the first conductive type semiconductor layer, and the first electrode pad and the third electrode pad are electrically connected to the first conductive type semiconductor layer of the first LED subunit and the third LED subunit, respectively.

[0044] The light emitting device may additionally include a first ohmic electrode disposed on the first conductivity type semiconductor layer of the first LED subunit, and the first electrode pad is connected to the first ohmic electrode.

[0045] The third electrode pad may be directly connected to the first conductivity type semiconductor layer of the third LED subunit.

[0046] The light emitting device may additionally include a first color filter disposed between the third transparent electrode and the second LED subunit, and a second color filter disposed between the first and second LED subunits.

[0047] The first color filter and the second color filter may include insulating layers having different refractive indices.

[0048] The common electrode pad and the third electrode pad are electrically connected to the third LED subunit through a hole that penetrates the second LED subunit.

[0049] The light emitting device may additionally include a substrate on which the third LED subunit is disposed.

[0050] The substrate may include a sapphire substrate or a gallium nitride substrate.

[0051] The light-emitting device may additionally include an insulating layer disposed between the first LED subunit and the electrode pad, and the electrode pad is electrically connected to the first, second and third LED subunits through the insulating layer.

[0052] The insulating layer may include one or more of a distributed Bragg reflector and a light blocking material.

[0053] The display device may include a circuit board and a plurality of light-emitting devices arranged on the circuit board, at least some of the light-emitting devices including light-emitting devices according to an exemplary embodiment, and the electrode pads are electrically connected to the circuit board.

[0054] Each of the light emitting devices may include a substrate coupled to the third LED subunit, and the substrates of the light emitting devices may be separated from each other.

[0055] A light emitting device according to an exemplary embodiment includes a substrate, a first LED subunit disposed on the substrate, a second LED subunit disposed on the first LED subunit, a third LED subunit disposed on the second LED subunit, and electrode pads electrically connected to the first, second, and third LED subunits, the electrode pads including a common electrode pad electrically connected to each of the first, second, and third LED subunits by a single through-hole via, and first, second, and third electrode pads connected to respective ones of the first, second, and third LED subunits.

[0056] The electrode pad is disposed between the substrate and the first LED subunit, and the through-hole via can include a plurality of connectors connected to the first, second, and third LED subunits, respectively, and the connectors can include a first portion having a width greater than the width of the through-hole via.

[0057] The first LED subunit may include a reflective electrode disposed on a lower surface thereof, the reflective electrode being contactable with a first portion of a corresponding connector.

[0058] The first, second and third LED subunits may be disposed between the electrode pad and the substrate, and the through-hole via may have a width that narrows in a direction from the electrode pad to the substrate.

[0059] The third LED subunit can include a reflective electrode disposed on its top surface, and the common electrode pad can directly contact the reflective electrode.

[0060] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. [Effects of the Invention]

[0061] Light emitting diodes and displays using the same constructed in accordance with the principles and exemplary embodiments of the present invention can increase the light emitting area of ​​each subpixel without increasing the pixel area.

[0062] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments provide high reliability due to a stable LED structure and simplified manufacturing process in which a single via can connect to one or more semiconductor layers of each LED stack.

[0063] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles of the present invention and some exemplary embodiments provide pixels that can be manufactured simultaneously to avoid the cumbersome process of individually packaging pixels.

[0064] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles and some exemplary embodiments of the present invention can be driven in an active matrix manner.

[0065] Light emitting diodes and displays using light emitting diodes, e.g., micro LEDs, constructed in accordance with the principles and exemplary embodiments of the present invention can reduce packaging process time.

[0066] Displays using light emitting diodes and light emitting diodes, e.g., micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments can prevent optical interference between the LED stacks by arranging the first, second, and third LED stacks on top of each other to emit light having decreasing wavelengths, e.g., the first, second, and third LED stacks can emit red light, green light, and blue light, respectively.

[0067] Light-emitting diodes and displays using light-emitting diodes, for example, micro LEDs, constructed according to the principles of the present invention and some exemplary embodiments do not require color filters arranged between LED stacks, which are typically formed between LED stacks to prevent the generation of secondary light due to light emitted from adjacent LED stacks, and can suppress the generation of secondary light between LED stacks.

[0068] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with the detailed description, serve to explain the concepts of the invention. [Brief explanation of the drawings]

[0069] [Figure 1] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line AA in FIG. [Figure 3A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 3B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 4A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 4B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 5A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 5B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 6A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 6B]1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 7A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 7B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 8A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 8B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 9A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 9B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 10A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 10B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 11A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 11B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 12A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 12B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 13A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 13B]1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 14A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 14B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 15A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 15B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 16A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 16B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 17] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment. [Figure 18] FIG. 18 is a schematic cross-sectional view taken along line BB in FIG. [Figure 19] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 20] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 21A] 1 is a schematic plan view of a light emitting device according to an example embodiment; [Figure 21B] FIG. 21B is a schematic cross-sectional view taken along line AA in FIG. 21A. [Figure 22] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 23] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 24] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 25] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 26A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 26B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 27A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 27B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 28A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 28B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 29] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 30A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 30B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 31A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 31B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 32A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 32B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 33A]1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 33B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 34A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 34B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 35A] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 35B] 1A-1C are schematic plan and cross-sectional views illustrating a method for fabricating a light emitting device according to an example embodiment. [Figure 36] 1 is a schematic cross-sectional view of a light emitting diode stack for a display according to an example embodiment. [Figure 37A] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 37B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 37C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 37D] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 37E] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 38] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 39] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 40] FIG. 40 is an enlarged plan view of one pixel of the display device of FIG. 39. [Figure 41] FIG. 41 is a schematic cross-sectional view taken along line AA in FIG. 40. [Figure 42] FIG. 41 is a schematic cross-sectional view taken along line BB in FIG. 40. [Figure 43A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43D] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43I] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43J] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 43K] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 44] FIG. 10 is a schematic circuit diagram of a display device according to another exemplary embodiment. [Figure 45] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment. [Figure 46] 1 is a schematic cross-sectional view of a light emitting diode stack for a display according to an example embodiment. [Figure 47A]1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 47B] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 47C] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 47D] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 47E] 1A-1C are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 48] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 49] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 50] FIG. 50 is an enlarged plan view of one pixel of the display device of FIG. 49. [Figure 51] FIG. 51 is a schematic cross-sectional view taken along line AA in FIG. 50. [Figure 52] FIG. 51 is a schematic cross-sectional view taken along line BB in FIG. 50. [Figure 53A] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53B] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53C] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53D] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53E] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53F] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53G] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53H] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53I] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53J] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 53K] 1A to 1C are schematic cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 54] FIG. 10 is a schematic circuit diagram of a display device according to another exemplary embodiment. [Figure 55] FIG. 10 is a schematic plan view of a display device according to another exemplary embodiment. [Figure 56] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 57] 1 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an example embodiment. [Figure 58] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 59A] 2A and 2B are top and bottom views of one pixel of a display device according to an exemplary embodiment. [Figure 59B] 2A and 2B are top and bottom views of one pixel of a display device according to an exemplary embodiment. [Figure 60A] FIG. 59B is a schematic cross-sectional view taken along line AA in FIG. 59A. [Figure 60B] FIG. 59B is a schematic cross-sectional view taken along line BB in FIG. 59A. [Figure 60C] FIG. 59B is a schematic cross-sectional view taken along line CC in FIG. 59A. [Figure 60D] FIG. 59B is a schematic cross-sectional view taken along line DD in FIG. 59A. [Figure 61A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 61B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 62A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 62B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 63A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 63B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 64A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 64B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 65A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 65B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 66A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 66B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 67A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 67B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 68A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 68B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 69] 1 is a schematic cross-sectional view of a light emitting diode pixel for a display according to another exemplary embodiment. [Figure 70] 2 is an enlarged plan view of one pixel of a display device according to an exemplary embodiment. [Figure 71A] FIG. 71 is a cross-sectional view taken along line GG in FIG. 70. [Figure 71B] FIG. 71 is a cross-sectional view taken along line HH in FIG. 70. [Figure 72] 1 is a schematic cross-sectional view of a light emitting diode (LED) stack for a display according to an example embodiment. [Figure 73A] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 73B] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 73C] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 73D] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 73E] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 73F] 1A-1C are schematic cross-sectional views illustrating a method for manufacturing a light emitting diode stack for a display according to an example embodiment. [Figure 74] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 75] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 76] FIG. 76 is an enlarged plan view of one pixel of the display device of FIG. 75. [Figure 77]FIG. 77 is a schematic cross-sectional view taken along line AA in FIG. 76. [Figure 78] FIG. 77 is a schematic cross-sectional view taken along line BB in FIG. 76. [Figure 79A] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79B] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79C] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79D] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79E] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79F] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79G] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 79H] 1A-1C are schematic plan views illustrating a method for manufacturing a display device according to an example embodiment. [Figure 80] 1 is a schematic cross-sectional view of a light emitting stack according to an example embodiment; [Figure 81A] 1 is a cross-sectional view of a light emitting stack according to an example embodiment. [Figure 81B] 1 is a cross-sectional view of a light emitting stack according to an example embodiment. [Figure 82] 1 is a cross-sectional view of a light-emitting stack structure including a wiring portion according to an exemplary embodiment. [Figure 83] 1 is a cross-sectional view of a light emitting stack according to an example embodiment. [Figure 84] FIG. 1 is a plan view of a display device according to an exemplary embodiment. [Figure 85] FIG. 85 is an enlarged plan view of a portion P1 of FIG. 84. [Figure 86]FIG. 2 is a structural diagram of a display device according to an exemplary embodiment. [Figure 87] FIG. 1 is a circuit diagram of one pixel of a passive-type display device. [Figure 88] FIG. 1 is a circuit diagram of one pixel of an active-type display device. [Figure 89] FIG. 2 is a plan view of a pixel according to an example embodiment. [Figure 90A] FIG. 89 is a cross-sectional view taken along line II' in FIG. 89. [Figure 90B] FIG. 89 is a cross-sectional view taken along line II-II' in FIG. [Figure 91A] 89, showing a step of stacking first to third epitaxial stacks on a substrate according to an exemplary embodiment. FIG. [Figure 91B] 89, showing a process of stacking first to third epitaxial stacks on a substrate according to an exemplary embodiment. FIG. [Figure 91C] 89, showing a process of stacking first to third epitaxial stacks on a substrate according to an exemplary embodiment. FIG. [Figure 92] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 93A] FIG. 93 is a cross-sectional view taken along line II' in FIG. 92. [Figure 93B] 93 is a cross-sectional view taken along line II-II' in FIG. 92. [Figure 94] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 95A] FIG. 95 is a cross-sectional view taken along line II' in FIG. 94. [Figure 95B] 95 is a cross-sectional view taken along line II-II' in FIG. 94. [Figure 96] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 97A] FIG. 97 is a cross-sectional view taken along line II' in FIG. 96. [Figure 97B] FIG. 97 is a cross-sectional view taken along line II-II' in FIG. 96. [Figure 97C] FIG. 97 is a cross-sectional view of FIG. 96. [Figure 97D] FIG. 97 is a cross-sectional view of FIG. 96. [Figure 98] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 99A] FIG. 99 is a cross-sectional view taken along line II' in FIG. 98. [Figure 99B] 99 is a cross-sectional view taken along line II-II' in FIG. 98. [Figure 100] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 101A] FIG. 101 is a cross-sectional view taken along line II' in FIG. [Figure 101B] 101 is a cross-sectional view taken along line II-II' in FIG. [Figure 102] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 103A] FIG. 103 is a cross-sectional view taken along line II' in FIG. [Figure 103B] 103 is a cross-sectional view taken along line II-II' in FIG. 102. [Figure 103C] FIG. 103 is a cross-sectional view of FIG. [Figure 103D] FIG. 103 is a cross-sectional view of FIG. [Figure 104] 1A to 1C are plan views sequentially illustrating a method of manufacturing pixels on a substrate. [Figure 105A] FIG. 105 is a cross-sectional view taken along line II' in FIG. [Figure 105B] FIG. 105 is a cross-sectional view taken along line II-II' in FIG. [Figure 106] 1 is a schematic plan view of a display device according to an exemplary embodiment; [Figure 107A] FIG. 107 is a cross-sectional view of the display device of FIG. 106. [Figure 107B] 1 is a schematic circuit diagram of a display device according to an exemplary embodiment; [Figure 108A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 108B]1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 108C] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 108D] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 108E] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 109A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 109B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 109C] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 109D] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 109E] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 110A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 110B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 110C] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 110D] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 111A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 111B]1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 111C] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 111D] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 112A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 112B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 112C] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 112D] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 113A] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 113B] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 114] 1A and 1B are schematic plan and cross-sectional views illustrating a method for manufacturing a display device according to an exemplary embodiment. [Figure 115A] 1 is a schematic cross-sectional view of a metallic bonding material according to an example embodiment. [Figure 115B] 1 is a schematic cross-sectional view of a metallic bonding material according to an example embodiment. [Figure 115C] 1 is a schematic cross-sectional view of a metallic bonding material according to an example embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0070] In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of various exemplary embodiments or examples of the present invention. As used herein, the terms "embodiment" and "embodiment" are interchangeable terms that refer to non-limiting examples of devices or methods that utilize one or more of the inventive concepts disclosed herein. However, it will be apparent that the various exemplary embodiments may be practiced without utilizing these specific details, using one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form to avoid unnecessarily obscuring the various exemplary embodiments. Additionally, the various exemplary embodiments may differ from one another, but are not necessarily exclusive. For example, specific shapes, configurations, and features of an exemplary embodiment may be used or implemented in other exemplary embodiments without departing from the inventive concept.

[0071] Unless otherwise expressly stated, it should be understood that the illustrated exemplary embodiments provide illustrative features of varying detail in some of the ways in which the inventive concept may be practically realized. Thus, unless otherwise expressly stated, the features, components, modules, layers, films, panels, regions, and / or aspects, etc. (hereinafter individually or collectively referred to as "elements") of the various embodiments may be differently combined, separated, interchanged, and / or rearranged without departing from the inventive concept.

[0072] The use of cross-sectional hatching and / or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, the presence, as well as the absence, of cross-sectional hatching or shading does not imply or indicate any preference or requirement for specific materials, material properties, dimensions, proportions, commonalities between the illustrated elements, and / or any other features, attributes, characteristics, etc., unless expressly stated. Also, in the accompanying drawings, the size and relative size of elements may be exaggerated for clarity and / or illustrative purposes. Certain steps may be performed in a different order than described, if different illustrative embodiments are feasible. For example, two consecutively described steps may be performed substantially simultaneously or in the reverse order from that described. Furthermore, like reference numerals represent like elements.

[0073] When an element, such as a layer, is referred to as being "on," "connected to," or "coupled to" another element or layer, the element may be directly on, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. However, when an element or layer is referred to as being "directly on," "directly connected to," or "directly coupled to" another element or layer, no intervening elements or layers are present. Thus, the term "connected" can refer to physical, electrical, and / or fluid connections, with or without intervening elements. Additionally, the D1, D2, and D3 axes are not limited to the three axes of a Cartesian coordinate system, such as the x, y, and z axes, but can be interpreted in a broader sense. For example, the D1, D2, and D3 axes may be perpendicular to one another, or may indicate different directions that are not perpendicular to one another. For purposes of this disclosure, "one or more of X, Y, and Z" and "one or more selected from the group consisting of X, Y, and Z" can be interpreted as X alone, Y alone, Z alone, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0074] In this specification, even though the terms "first," "second," and the like are used to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Therefore, a first element described below may be called a second element without departing from the teachings of the present disclosure.

[0075] Spatially relative terms such as "below," "beneath," "beneath," "lower," "above," "upper," "above," "higher" (e.g., as in "sidewall"), "side," and the like are used herein for descriptive purposes and to describe the relationship of one element to other elements as shown in the figures. Spatially relative terms are intended to include different orientations of the device during use, operation, and / or manufacture in addition to the orientation shown in the figures. For example, if the device in the figures were turned over, elements described as "beneath" or "below" other elements or features would be oriented "above" the other elements or features. Thus, the exemplary term "beneath" can encompass both an above and below orientation. Also, the device may be oriented differently (e.g., rotated 90 degrees or oriented in other directions), and thus, the spatially relative predicates used herein can be interpreted accordingly.

[0076] The terminology used herein is for the purpose of describing particular embodiments and is not limiting. As used herein, the singular forms "a," "an," "an," "the," and / or "including" further include the plural forms unless the context clearly dictates otherwise. Additionally, as used herein, the terms "comprises," "comprising," "includes," and / or "comprising" specify the presence of a stated feature, integer, step, operation, element, component, and / or group thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or group thereof. Additionally, as used herein, the terms "substantially," "about," and other similar terms are used as terms of approximation, not terms of degree, and as such, are used to account for inherent deviations from measured, calculated, and / or provided values ​​that are discernible by one of ordinary skill in the art.

[0077] Various illustrative embodiments are described below with reference to cross-sectional and / or exploded illustrations that are schematic illustrations of idealized illustrative embodiments and / or intermediate structures. As such, variations from the shapes of the illustrative illustrations are to be expected as a result, for example, of manufacturing methods and / or tolerances. Therefore, the illustrative embodiments disclosed herein should not be construed as necessarily limited to the shapes of the particular illustrated regions, but should be construed to include, for example, deviations in shapes that result from manufacturing. In this manner, the regions illustrated in the figures may be schematic in nature and the shapes of the regions may not reflect the actual shapes of the regions in a device, and as such, are not necessarily intended to be limiting.

[0078] Unless otherwise defined, all terms used herein (including technical or scientific terms) have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure belongs. Terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art, and should not be interpreted in an idealized or overly formal manner unless explicitly defined herein.

[0079] As used herein, a light emitting device or light emitting diode according to an exemplary embodiment has a diameter of about 10,000 μm, as is known in the art. 2 In other exemplary embodiments, the micro LEDs may include micro LEDs having a surface area of ​​less than about 4,000 μm, depending on the particular application. 2 Less than or about 2,500 μm 2 It may have a surface area of ​​less than 1000 nm.

[0080] 1 is a schematic plan view of a display device according to an exemplary embodiment, and FIG. 2 is a schematic cross-sectional view taken along line AA in FIG.

[0081] 1 and 2 , the display device may include a substrate 51, electrode pads 53 a, 53 b, 53 c, ​​and 53 d, a first LED stack 23, a second LED stack 33, a third LED stack 43, a first reflective electrode 25, a second transparent electrode 35, a third transparent electrode 45, a first color filter 37, a second color filter 47, a first bonding layer 55, a second bonding layer 65, and a third bonding layer 75. In addition, the display device may include a plurality of connectors 59 a, 59 b, 59 c, 59 d, 69 b, 69 c, 69 d, 79 c, and 79 d, and insulating layers 57, 67, and 77. As used herein, a connector may refer to any type of structure, including a through-hole, a via, a wire, a line, a conductive material, etc., that serves to electrically and / or mechanically connect two elements, such as layers.

[0082] The substrate 51 supports the LED stacks 23, 33, and 43. The substrate 51 may also have internal circuits. For example, the substrate 51 may be a silicon substrate with thin film transistors formed therein. TFT substrates have been widely used in the display field, such as the LCD display field, to drive display devices in an active matrix manner. Since TFT substrates are well known in the art, a detailed description of the structure of a TFT substrate will be omitted.

[0083] Although FIGS. 1 and 2 show one unit pixel disposed on the substrate 51, a plurality of unit pixels may be arranged on the substrate 51, and the plurality of unit pixels can be driven in an active matrix manner.

[0084] Electrode pads 53a, 53b, 53c, and 53d are exposed on substrate 51. Each of electrode pads 53a, 53b, 53c, and 53d is connected to one of the subpixels of a unit pixel arranged on substrate 51, while electrode pad 53d is connected to each of the three subpixels. Each of electrode pads 53a, 53b, 53c, and 53d is connected to an internal circuit of substrate 51.

[0085] The first LED stack 23, the second LED stack 33, and the third LED stack 43 each include an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multiple quantum well structure.

[0086] The closer to the substrate 51, the longer wavelength light is emitted from the LED stack. For example, the first LED stack 23 may be an inorganic light-emitting diode configured to emit red light, the second LED stack 33 may be an inorganic light-emitting diode configured to emit green light, and the third LED stack 43 may be an inorganic light-emitting diode configured to emit blue light. The first LED stack 23 may include a GaInP-based well layer, and the second LED stack 33 and the third LED stack 43 may include GaInN-based well layers. However, the inventive concept is not limited in this respect. If the pixel includes micro LEDs, the first LED stack 23 may emit any one of red, green, and blue light, and the second and third LED stacks 33 and 43 may emit the other one of red, green, and blue light without adversely affecting operation due to the small form factor of the micro LEDs.

[0087] The surfaces of the LED stacks 23, 33, and 43 may be n-type and p-type semiconductor layers, respectively. Hereinafter, the upper and lower surfaces of the first to third LED stacks 23, 33, and 43 will be described as n-type and p-type, respectively. However, the concept of the present invention is not limited thereto, and the types of the upper and lower surfaces of the LED stacks may be reversed or modified in various ways.

[0088] When the top surface of the third LED stack 43 is n-type, the top surface of the third LED stack 43 can be surface-textured, such as by chemical etching, to form a roughened surface. The top surfaces of the first LED stack 23 and the second LED stack 33 are also surface-textured. However, when the second LED stack 33 emits green light, it is preferable to increase the luminous efficiency of the first LED stack 23 and the third LED stack 43 to a greater extent than that of the second LED stack 33 because green light has higher visibility than red and blue light. In this way, the first LED stack 23 and the third LED stack 43 are surface-textured to improve the light extraction efficiency without surface-texturing the second LED stack 33. In this manner, the luminous intensities of the red light, green light, and blue light can be balanced and adjusted to have substantially similar levels.

[0089] The first LED stack 23 is disposed adjacent to the support substrate 51, the second LED stack 33 is disposed on the first LED stack 23, and the third LED stack 43 is disposed on the second LED stack 33. Because the first LED stack 23 can emit light having a longer wavelength than the second and third LED stacks 33 and 43, light generated from the first LED stack 23 is transmitted through the second and third LED stacks 33 and 43 and emitted to the outside. In addition, because the second LED stack 33 can emit light having a longer wavelength than the third LED stack 43, light generated from the second LED stack 33 is transmitted through the third LED stack 43 and emitted to the outside.

[0090] The first reflective electrode 25 is in ohmic contact with the p-type semiconductor layer of the first LED stack 23 and reflects light generated from the first LED stack 23. For example, the first reflective electrode 25 may include an ohmic contact layer 25a and a reflective layer 25b.

[0091] To prevent light absorption by the ohmic contact layer 25a, the ohmic contact layer 25a is formed within a predetermined area. For example, the ohmic contact layer 25a is disposed near the periphery of the first LED stack 23 and arranged in a substantially circular pattern. The contact area of ​​the ohmic contact layer 25a with the first LED stack 23 may be 25% or less, or in some exemplary embodiments, 10% or less. Although the contact area of ​​the ohmic contact layer 25a is relatively small, when the area of ​​the first LED stack 23 is approximately 200 μm or less in size, current can be uniformly distributed within the first LED stack 23. The ohmic contact layer 25a is formed of a transparent conductive oxide or a gold (Au) alloy such as Au(Zn) or Au(Be).

[0092] The reflective layer 25b may cover the ohmic contact layer 25a and the lower surface of the first LED stack 23. However, as shown in FIG. 1 , the reflective layer 25b exposes the lower surface of the first LED stack 23 in the area surrounding the connectors 59a, 59b, 59c, and 59d. More specifically, the reflective layer 25b may expose the lower surface of the first LED stack 23 in the area surrounded by the ohmic contact layer 25a. The reflective layer 25b may include a reflective metal layer made of Al, Ag, or the like. In addition, the reflective layer 25b may include metal adhesion layers made of Ti, Ta, Ni, Cr, or the like on the upper and lower surfaces of the reflective metal layer to improve adhesion of the reflective metal layer. The reflective layer 25b is formed of a metal layer that has a high reflectivity for light generated from the first LED stack 23, for example, red light. On the other hand, the reflective layer 25b may have a relatively low reflectance for light, for example, green light or blue light, generated from the second LED stack 33 or the third LED stack 43. Therefore, the reflective layer 25b can reduce optical interference by absorbing the light generated from the second and third LED stacks 33 and 43 and emitted toward the support substrate 51. Gold (Au) has a high reflectance for red light and a low reflectance for green light or blue light, and therefore can be used to form the reflective layer 25b disposed on the first LED stack 23.

[0093] The second transparent electrode 35 makes ohmic contact with the p-type semiconductor layer of the second LED stack 33. The second transparent electrode 35 is formed of a metal layer or a conductive oxide layer that is transparent to red and green light. The third transparent electrode 45 makes ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third transparent electrode 45 is formed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light. The second transparent electrode 35 and the third transparent electrode 45 can make ohmic contact with the p-type semiconductor layer of each LED stack to aid current spreading. Examples of conductive oxide layers used for the second and third transparent electrodes 35 and 45 include SnO2, InO2, ITO, ZnO, IZO, etc.

[0094] The first color filter 37 is disposed between the first LED stack 23 and the second LED stack 33. In addition, the second color filter 47 is disposed between the second LED stack 33 and the third LED stack 43. The first color filter 37 can transmit light generated from the first LED stack 23 and reflect light generated from the second LED stack 33. The second color filter 47 can transmit light generated from the first and second LED stacks 23 and 33 and reflect light generated from the third LED stack 43. In this manner, the light generated from the first LED stack 23 is emitted to the outside via the second LED stack 33 and the third LED stack 43, and the light generated from the second LED stack 33 is emitted to the outside via the third LED stack 43. In addition, it is possible to prevent light generated from the second LED stack 33 from entering the first LED stack 23 and being lost, or it is possible to prevent light generated from the third LED stack 43 from entering the second LED stack 33 and being lost.

[0095] In some exemplary embodiments, the first color filter 37 may further reflect light generated from the third LED stack 43 .

[0096] The first and second color filters 37 and 47 may be, for example, low-pass filters that pass only light in a low wavelength range, e.g., a long wavelength range, band-pass filters that pass only light in a predetermined wavelength range, or band-stop filters that block only light in a predetermined wavelength range. More specifically, the first and second color filters 37 and 47 can be formed by alternately stacking insulating layers having different refractive indices. For example, the color filters can be formed by alternately stacking TiO2 and SiO2. The first and second color filters 37 and 47 can include a distributed Bragg reflector (DBR). The stopband of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2. The low-pass filter and the band-pass filter can also be formed by alternately stacking insulating layers having different refractive indices.

[0097] A first bonding layer 55 bonds the first LED stack 23 to the substrate 51. As shown, the first reflective electrode 25 can be in contact with the first bonding layer 55. The first bonding layer 55 can be transparent or opaque.

[0098] The second bonding layer 65 bonds the second LED stack 33 to the first LED stack 23. As shown, the second bonding layer 65 can be in contact with the first LED stack 23 and the first color filter 37. The second bonding layer 65 transmits light generated from the first LED stack 23. The second bonding layer 65 is formed, for example, of spin-on-glass having light-transmitting properties.

[0099] The third bonding layer 75 bonds the third LED stack 43 to the second LED stack 33. As shown, the third bonding layer 75 can be in contact with the second LED stack 33 and the second color filter 47. However, the concept of the present invention is not limited thereto, and a transparent conductive layer can be disposed on the second LED stack 33. The third bonding layer 75 transmits light generated from the first LED stack 23 and the second LED stack 33. The third bonding layer 75 is formed, for example, of spin-on-glass having light-transmitting properties.

[0100] Bonding layers 55, 65, and 75 are formed by forming a transparent organic or inorganic layer on each of the two objects to be bonded, and then bonding the objects together. Examples of organic layers include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc. Examples of inorganic layers include Al2O3, SiO2, SiN x The organic layer may be bonded at high vacuum and pressure, and the surface of the inorganic layer may be planarized, for example by chemical mechanical polishing (CMP), after which the surface energy is lowered, for example by plasma, to allow bonding at high vacuum.

[0101] The first-first connector 59d electrically connects the first reflective electrode 25 and the electrode pad 53d to each other. In this manner, the first-first connector 59d is electrically connected to the lower surface of the first LED stack 23. As shown in the figure, the first-first connector 59d can penetrate the first LED stack 23. However, the concept of the present invention is not limited thereto, and the first-first connector 59d may be formed on a side surface of the first LED stack 23. An insulating layer 57 is interposed between the first-first connector 59d and the first LED stack 23 to prevent the first-first connector 59d from shorting to the upper surface of the first LED stack 23.

[0102] The first-second connector 59a electrically connects the upper surface of the first LED stack 23 to the electrode pad 53a on the substrate 51. The first-second connector 59a is connected to the upper surface of the first LED stack 23 and connects to the electrode pad 53a through the first LED stack 23. An insulating layer 57 is interposed between the first LED stack 23 and the first-second connector 59a, which can prevent the first-second connector 59a from shorting to the lower surface of the first LED stack 23.

[0103] The first-third connector 59b and the first-fourth connector 59c are connected to the electrode pads 53b and 53c, respectively, through the first LED stack 23. The first-third connector 59b and the first-fourth connector 59c are insulated from the first LED stack 23 by an insulating layer 57 interposed between the first LED stack 23 and the connectors 59b and 59c.

[0104] The first-third connector 59b and the first-fourth connector 59c can function as intermediate connectors, or these configurations can be omitted in some exemplary embodiments.

[0105] The second-1 connector 69d is disposed to electrically connect the second transparent electrode 35 to the electrode pad 53d. The second-1 connector 69d is electrically connected to the lower surface of the second LED stack 33 via the second transparent electrode 35. As shown, the second-1 connector 69d can penetrate the second LED stack 33. However, the concept of the present invention is not limited thereto, and the second-1 connector 69d may be formed on a side surface of the second LED stack 33. An insulating layer 67 is interposed between the second-1 connector 69d and the second LED stack 33 to prevent the second-1 connector 69d from shorting to the upper surface of the second LED stack 33.

[0106] As shown in Fig. 2, the second-first connector 69d is connected to the first-first connector 59d and electrically connected to the electrode pad 53d. In this case, the first-first connector 59d can function as an intermediate connector. In addition, as shown in Fig. 2, the second-first connector 69d is stacked vertically on the first-first connector 59d.

[0107] The second-second connector 69b is disposed to electrically connect the upper surface of the second LED stack 33 to the electrode pad 53b. The second-second connector 69b is connected to the upper surface of the second LED stack 33 and can penetrate the second LED stack 33. As shown in the figure, the second-second connector 69b is connected to the first-third connector 59b and electrically connected to the electrode pad 53b. The second-second connector 69b may also be directly connected to the electrode pad 53b. In this case, the first-third connector 59b is omitted.

[0108] The insulating layer 67 is interposed between the second LED stack 33 and the 2-2 connector 69b, and can prevent the 2-2 connector 69b from shorting to the lower surface of the second LED stack 33.

[0109] The 2-3 connector 69c is disposed so as to penetrate the second LED stack 33. The 2-3 connector 69c is electrically connected to the electrode pad 53c, and is connected to, for example, the 1-4 connector 59c. The 2-3 connector 69c is insulated from the second LED stack 33 by an insulating layer 67 interposed between the second LED stack 33 and the 2-3 connector 69c.

[0110] The second-third connector 69c can function as an intermediate connector, or these configurations can be omitted in some exemplary embodiments.

[0111] The third-1 connector 79d is disposed to connect the third transparent electrode 45 and the electrode pad 53d to each other. The third-1 connector 79d is electrically connected to the lower surface of the third LED stack 43 via the third transparent electrode 45. As shown, the third-1 connector 79d can penetrate the third LED stack 43. However, the concept of the present invention is not limited thereto, and the third-1 connector 79d may be formed on a side surface of the third LED stack 43. An insulating layer 77 is interposed between the third-1 connector 79d and the third LED stack 43 to prevent the third-1 connector 79d from shorting to the upper surface of the third LED stack 43.

[0112] As shown in FIG. 2, the 3-1 connector 79d is connected to the 2-1 connector 69d and electrically connected to the electrode pad 53d. In this case, the 2-1 connector 69d and the 1-1 connector 59d can function as intermediate connectors. Additionally, as shown in FIG. 2, the 3-1 connector 79d is stacked vertically on the 2-1 connector 69d. Therefore, the 1-1 connector 59d, the 2-1 connector 69d, and the 3-1 connector 79d are electrically connected to each other and stacked vertically. The connectors are arranged in the light emission direction to absorb light. If the connectors were spaced apart from each other laterally, the light-emitting area would be reduced, which could lead to increased light loss. However, the connectors according to the exemplary embodiment are stacked vertically, reducing the light loss generated from the first LED stack 23 and the second LED stack 33.

[0113] The 3-2 connector 79c is disposed to connect the upper surface of the third LED stack 43 and the electrode pad 53c to each other. The 3-2 connector 79c is connected to the upper surface of the third LED stack 43 and can penetrate the third LED stack 43. As shown in the figure, the 3-2 connector 79c is connected to the 2-3 connector 69c and electrically connected to the electrode pad 53c. The 3-2 connector 79c may be directly connected to the electrode pad 53c. In this case, the 2-3 connector 69c can be omitted.

[0114] Meanwhile, the insulating layer 77 is interposed between the third LED stack 43 and the 3-2 connector 79c, and can prevent the 3-2 connector 79c from shorting to the lower surface of the third LED stack 43.

[0115] As shown, the 3-2 connector 79c, the 2-3 connector 69c and the 1-4 connector 59c are stacked vertically, which can reduce optical loss.

[0116] To prevent optical interference between pixels due to light emitted from the first LED stack 23, the second LED stack 33, and the third LED stack 43 to their side surfaces, a light-reflecting layer or a light-blocking material layer is formed to cover the side surfaces of the first to third LED stacks 23, 33, and 43. Examples of the light-reflecting layer include a distributed Bragg reflector, or an insulating layer made of SiO2 with a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. Black epoxy, for example, can be used as the light-blocking layer. The light-blocking material prevents optical interference between light-emitting elements and increases the contrast ratio of the image.

[0117] According to an exemplary embodiment, the first LED stack 23 is electrically connected to electrode pads 53d and 53a, the second LED stack 33 is electrically connected to electrode pads 53d and 53b, and the third LED stack 43 is electrically connected to electrode pads 53d and 53c. Thus, the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 are electrically connected in common to the electrode pad 53d, and the cathodes are electrically connected to different electrode pads 53a, 53b, and 53c, respectively. Therefore, the first to third LED stacks 23, 33, and 43 can be independently driven. Furthermore, these LED stacks 23, 33, and 43 are disposed on a thin-film transistor substrate 51 and electrically connected to the internal circuitry of the substrate 51, enabling active-matrix driving.

[0118] Figures 3A, 3B, 4A, 4B, 5A, 5B, 6A, 6B, 7A, 7B, 8A, 8B, 9A, 9B, 10A, 10B, 11A, 11B, 12A, 12B, 13A, 13B, 14A, 14B, 15A, 15B, 16A, and 16B are schematic plan views and schematic cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment of the present disclosure. In the figures, each plan view corresponds to the plan view of Figure 1, and each cross-sectional view is taken along line AA in Figure 1.

[0119] 3A and 3B, the first LED stack 23 is grown on the first substrate 21. The first substrate 21 may be, for example, a GaAs substrate. Additionally, the first LED stack 23 is formed of an AlGaInP-based semiconductor layer and includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0120] An ohmic contact layer 25a and a reflective layer 25b are formed on the first LED stack 23 to form the first reflective electrode 25. The ohmic contact layer 25a is formed using a lift-off method or the like, and is formed so as to be disposed near the periphery of the first LED stack 23. As shown in the figure, the ohmic contact layer 25a is formed to have a substantially annular shape.

[0121] The reflective layer 25b covers the ohmic contact layer 25a and the first LED stack 23. The reflective layer 25b is formed to expose each peripheral edge of the first LED stack 23. More specifically, the reflective layer 25b may have an opening 25h that exposes the first LED stack 23 including the ohmic contact layer 25a. The reflective layer 25b is formed of, for example, gold (Au) using a lift-off method or the like.

[0122] 4A and 4B, a second LED stack 33 is grown on a second substrate 31, and a second transparent electrode 35 and a first color filter 37 are formed on the second LED stack 33. The second LED stack 33 is formed of a gallium nitride-based semiconductor layer and may include a GaInN-based well layer. The second substrate 31 on which the gallium nitride-based semiconductor layer can be grown is different from the first substrate 21. The composition ratio of GaInN may be determined so that the second LED stack 33 can emit green light. Meanwhile, the second transparent electrode 35 forms ohmic contact with the p-type semiconductor layer.

[0123] 5A and 5B, a third LED stack 43 is grown on a third substrate 41, and a third transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 is formed of a gallium nitride-based semiconductor layer and may include a GaInN-based well layer. The third substrate 41 on which the gallium nitride-based semiconductor layer can be grown is different from the first substrate 21. The composition ratio of GaInN may be determined so that the third LED stack 43 can emit blue light. Meanwhile, the third transparent electrode 45 forms ohmic contact with the p-type semiconductor layer.

[0124] The first color filter 37 and the second color filter 47 are substantially the same as those described with reference to FIG. 1, and therefore a detailed description thereof will be omitted to avoid redundancy.

[0125] 6A and 6B, electrode pads 53a, 53b, 53c, and 53d are formed on a substrate 51. The substrate 51 may be a substrate made of Si having thin film transistors therein. Each of the electrode pads 53a, 53b, 53c, and 53d, which corresponds to one pixel area, is disposed in each of the four peripheral regions of the substrate 51.

[0126] The first LED stack 23, the second LED stack 33, the third LED stack 43 and the electrode pads 53a, 53b, 53c and 53d are formed individually on different substrates, and the order of their formation is not particularly limited.

[0127] 7A and 7B , the first LED stack 23 is bonded to the substrate 51 via a first bonding layer 55. The first bonding layer 55 is disposed on the substrate 51, and the first reflective electrode 25 is disposed facing the substrate 51 and bonded to the first bonding layer 55. Alternatively, bonding material layers may be formed on the substrate 51 and the first LED stack 23, and then the first LED stack 23 may be bonded to the substrate 51 by bonding the bonding material layers together. Meanwhile, the first substrate 21 can be removed from the first LED stack 23 by chemical etching or the like. In this manner, the n-type semiconductor layer of the first LED stack 23 is exposed on the upper surface. The exposed n-type semiconductor layer is subjected to surface texturing.

[0128] 8A and 8B, the first LED stack 23 is patterned to expose a portion of the first reflective electrode 25. To avoid damaging the reflective layer 25b, the ohmic contact layer 25a may be exposed. In addition, the first LED stack 23 and the first bonding layer 55 are patterned to form openings to expose the electrode pads 53a, 53b, 53c, and 53d.

[0129] 9A and 9B, an insulating layer 57 is formed to cover the side surfaces of the first LED stack 23 within the opening. The insulating layer 57 may further partially cover the top surface of the first LED stack 23. The insulating layer 57 is formed to expose the first reflective electrode 25 and the electrode pads 53a, 53b, 53c, and 53d.

[0130] 10A and 10B, connectors 59a, 59b, 59c, and 59d are formed to be connectable to the exposed electrode pads 53a, 53b, 53c, and 53d, respectively. The 1-1 connector 59d is connected to the first reflective electrode 25 and also to the electrode pad 53d. Therefore, the lower surface of the first LED stack 23 and the electrode pad 53d are electrically connected to each other by the 1-1 connector 59d. In addition, the 1-2 connector 59a is connected to the upper surface of the first LED stack 23 and also to the electrode pad 53a. Therefore, the upper surface of the first LED stack 23 and the electrode pad 53a are electrically connected to each other by the 1-2 connector 59a. The 1-3 connector 59b and the 1-4 connector 59c are insulated from the first LED stack 23 by an insulating layer 57.

[0131] 11A and 11B , the second LED stack 33 of FIGS. 4A and 4B is coupled to the first LED stack 23, on which the 1-1, 1-2, 1-3, and 1-4 connectors 59d, 59a, 59b, and 59c are formed, via a second bonding layer 65. The first color filter 37 is bonded to the second bonding layer 65 and is arranged facing the first LED stack 23. The second bonding layer 65 may be pre-disposed on the first LED stack 23. The first color filter 37 is bonded to the second bonding layer 65 and is arranged facing the second bonding layer 65. Alternatively, bonding material layers may be formed on each of the first LED stack 23 and the first color filter 37, and the bonding material layers are bonded to each other to couple the second LED stack 33 to the first LED stack 23. Meanwhile, the second substrate 31 is separated from the second LED stack 33 using a laser lift-off method, a chemical lift-off method, or the like, thereby exposing the n-type semiconductor layer of the second LED stack 33. The exposed n-type semiconductor layer is subjected to surface texturing by chemical etching, or the like. However, the surface texturing step on the second LED stack 33 may be omitted in some exemplary embodiments.

[0132] 12A and 12B, the second LED stack 33 is patterned to expose the second transparent electrode 35, and the exposed second transparent electrode 35, first color filter 37, and second bonding layer 65 are etched to form an opening for exposing the 1-1 connector 59d. Openings for exposing the 1-3 connector 59b and the 1-4 connector 59c may also be formed.

[0133] 13A and 13B, an insulating layer 67 is formed to cover the side surfaces of the exposed openings. The insulating layer 67 exposes the second transparent electrode 35, as well as the 1-1 connector 59d, the 1-3 connector 59b, and the 1-4 connector 59c.

[0134] A second-first connector 69d, a second-second connector 69b, and a second-third connector 69c are formed in the openings. The second-first connector 69d electrically connects the second transparent electrode 35 and the first-first connector 59d to each other and is insulated from the upper surface of the second LED stack 33 by an insulating layer 67. The second-second connector 69b is connected to the upper surface of the second LED stack 33 and the first-third connector 59b. The second-second connector 69b is electrically connected to the electrode pad 53b via the first-third connector 59b. The second-second connector 69b is insulated from the lower surface of the second LED stack 33 and the second transparent electrode 35 by the insulating layer 67.

[0135] On the other hand, the second-third connector 69c is connected to the first-fourth connector 59c and is insulated from the second LED stack 33 and the second transparent electrode 35 by the insulating layer 67.

[0136] 14A and 14B , the third LED stack 43 of FIGS. 5A and 5B is coupled to the second LED stack 33, on which the 2-1, 2-2, and 2-3 connectors 69d, 69b, and 69c are formed, via a third bonding layer 75. The second color filter 47 is bonded to the third bonding layer 75 and arranged facing the second LED stack 33. The third bonding layer 75 may be pre-disposed on the second LED stack 33, and the second color filter 47 may be bonded to the third bonding layer 75 or arranged facing the third bonding layer 75. Alternatively, bonding material layers may be formed on each of the second LED stack 33 and the second color filter 47, and the bonding material layers may be bonded to each other to bond the third LED stack 43 to the second LED stack 33. Meanwhile, the third substrate 41 is separated from the third LED stack 43 using laser lift-off, chemical lift-off, or the like. In this way, the n-type semiconductor layer of the third LED stack 43 is exposed. The exposed n-type semiconductor layer is subjected to surface texturing by chemical etching or the like.

[0137] 15A and 15B, the third LED stack 43 is patterned to expose the third transparent electrode 45, and the exposed third transparent electrode 45, the second color filter 47, and the third bonding layer 75 are etched to form an opening for exposing the 2-1 connector 69d. An opening for exposing the 2-3 connector 69c may also be formed.

[0138] 16A and 16B, an insulating layer 77 is formed to cover the side surfaces of the exposed openings. The insulating layer 77 exposes the third transparent electrode 45, as well as the 2-1 connector 69d and the 2-3 connector 69c.

[0139] A third-first connector 79d and a third-second connector 79c are formed in the openings. The third-first connector 79d electrically connects the third transparent electrode 45 and the second-first connector 69d to each other and is insulated from the top surface of the third LED stack 43 by an insulating layer 77. The third-second connector 79c is connected to the top surface of the third LED stack 43 and the second-third connector 69c. The third-second connector 79c is electrically connected to the electrode pad 53c via the second-third connector 69c and the first-fourth connector 59c. The third-second connector 79c is insulated from the bottom surface of the third LED stack 43 and the third transparent electrode 45 by the insulating layer 77.

[0140] According to the exemplary embodiment, a unit pixel is provided having the anodes of the first to third LED stacks 23, 33 and 43 electrically connected in common with each other and the cathodes thereof connected independently.

[0141] Although a method for manufacturing one unit pixel has been described using exemplary embodiments, a display device may include a plurality of unit pixels arranged in a matrix on a substrate 51. The unit pixels are spaced apart from one another. In this case, regions of the first to third LED stacks 23, 33, and 43 corresponding to the unit pixels, respectively, may be pre-separated from one another on the substrates 21, 31, and 41. Alternatively, when the LED stacks 23, 33, and 43 are patterned after being bonded to the substrate 51, the regions of the LED stacks may be separated into regions corresponding to each pixel region. Therefore, according to exemplary embodiments, a display device having a plurality of unit pixels on a substrate 51 may eliminate the need to individually mount pixels having small sizes.

[0142] In addition, a light-reflecting layer or a light-blocking material layer may be added to cover the side of the pixel to prevent optical interference between pixels. Examples of the light-reflecting layer include a distributed Bragg reflector, or an insulating layer made of SiO2 with a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. For example, black epoxy can be used as the light-blocking layer. The light-blocking material prevents optical interference between light-emitting elements and increases the contrast ratio of the image.

[0143] Fig. 17 is a schematic plan view of a display device according to another exemplary embodiment, and Fig. 18 is a schematic cross-sectional view taken along line BB in Fig. 17.

[0144] 17 and 18, the display device according to the exemplary embodiment is generally similar to the display device described with reference to FIGS. 1 and 2, except that the cathodes of the first to third LED stacks 23, 33 and 43 are electrically connected in common and the anodes are individually connected.

[0145] In particular, the 1-1 connector 159d electrically connects the first reflective electrode 25 to the electrode pad 153d, the 2-1 connector 169a electrically connects the second transparent electrode 35 to the electrode pad 153a, and the 3-1 connector 179b electrically connects the third transparent electrode 45 to the electrode pad 153b.

[0146] In addition, the 1-2 connector 159c is connected to the upper surface of the first LED stack 23 and the electrode pad 153c. The 2-2 connector 169c is connected to the upper surface of the second LED stack 33 and the 1-2 connector 159c. The 3-2 connector 179c is connected to the upper surface of the third LED stack 43 and the 2-2 connector 169c. As shown, the 1-2, 2-2, and 3-2 connectors 159c, 169c, and 179c are stacked vertically. In addition, the 3-2 connector 179c is connected to the electrode pad 153b via the intermediate connectors 169b and 159b, and the connectors 159b, 169b, and 179b are also stacked vertically.

[0147] FIG. 19 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0148] Referring to FIG. 19, a driving circuit according to an exemplary embodiment includes two or more transistors Tr1 and Tr2 and a capacitor. When a power supply is connected to the select lines Vrow1 to Vrow3 and a data voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. A charge is charged in the corresponding capacitor according to the value of the data lines Vdata1 to Vdata3. Because the turn-on state of the transistor Tr2 is maintained by the charged voltage of the capacitor, the voltage of the capacitor can be maintained even when the power supply is cut off, and the voltage is applied to the light-emitting diodes LED1 to LED3. In addition, the current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the value of the data lines Vdata1 to Vdata3. The current is continuously supplied via the current supply source Vdd, thereby enabling continuous light emission.

[0149] The transistors Tr1 and Tr2 and the capacitor are formed in a substrate 51. Here, the light-emitting diodes LED1 to LED3 correspond to the first to third LED stacks 23, 33, and 43, respectively, which are stacked as one pixel. The anodes of the first to third LED stacks are connected to the transistor Tr2, and the cathodes thereof are grounded. According to an exemplary embodiment, the first to third LED stacks 23, 33, and 43 are commonly connected to each other and grounded.

[0150] 19 shows a circuit diagram for active matrix driving according to an exemplary embodiment, the inventive concept is not limited thereto, and other circuits may be used. Additionally, although the anodes of the light emitting diodes LED1-LED3 are described as being connected to different transistors Tr2 and the cathodes thereof are described as being grounded, in some exemplary embodiments, the anodes of the first through third LED stacks 23, 33, and 43 may be commonly connected, and the cathodes thereof may be connected to different transistors.

[0151] FIG. 20 is a schematic plan view of a display device according to an exemplary embodiment.

[0152] Referring to FIG. 20, the display device includes a circuit board 201 and a plurality of light emitting devices 200 .

[0153] The circuit board 201 may include circuits for passive matrix driving or active matrix driving. In an exemplary embodiment, the circuit board 201 may include wires and resistors therein. In another exemplary embodiment, the circuit board 201 may include wires, transistors, and capacitors. The circuit board 201 may further have pads on its top side to allow the circuits disposed therein to be electrically connected.

[0154] A plurality of light-emitting devices 200 are arranged on a circuit board 201. Each light-emitting device 200 constitutes one pixel. The light-emitting devices 200 have electrode pads 281 a, 281 b, 281 c, and 281 d, which are electrically connected to the circuit board 201. The light-emitting devices 200 may further include a substrate 241 on the upper surface. Since the light-emitting devices 200 are spaced apart from each other, the substrates 241 disposed on the upper surfaces of the light-emitting devices 200 are also spaced apart from each other.

[0155] A specific configuration of the light-emitting device 200 will be described in detail with reference to Figures 21A and 21B. Figure 21A is a schematic plan view of the light-emitting device 200 according to an exemplary embodiment, and Figure 21B is a cross-sectional view taken along line AA in Figure 21A. Although the electrode pads 281a, 281b, 281c, and 281d are shown arranged on the top side, the concept of the present invention is not limited thereto, and the light-emitting device 200 may be flip-bonded onto the circuit board 201 of Figure 20, in which case the electrode pads 281a, 281b, 281c, and 281d are arranged on the bottom side.

[0156] 21A and 21B, the light-emitting device 200 includes a substrate 241, electrode pads 281a, 281b, 281c, and 281d, a first LED stack 223, a second LED stack 233, a third LED stack 243, an insulating layer 271, a first reflective electrode 228, a second transparent electrode 235, a third transparent electrode 245, a first ohmic electrode 226, a first color filter 247, a second color filter 267, a first bonding layer 249, a second bonding layer 269, and an upper insulating layer 273.

[0157] The substrate 241 can support the LED stacks 223, 233, and 243. The substrate 241 may also be a growth substrate for growing the third LED stack 243. For example, the substrate 241 may be a sapphire substrate or a gallium nitride substrate, particularly a patterned sapphire substrate. The first, second, and third LED stacks are arranged on the substrate 241 in the order of the third LED stack 243, the second LED stack 233, and the first LED stack 223. A single third LED stack is disposed on one substrate 241, so that the light emitting device 200 has a single-pixel, single-chip structure. In some exemplary embodiments, the substrate 241 can be omitted, and the lower surface of the third LED stack 243 may be exposed. In this case, a roughened surface is formed on the lower surface of the third LED stack 243 by surface texturing.

[0158] The first LED stack 223, the second LED stack 233, and the third LED stack 243 each include a first conductive type semiconductor layer 223 a, 233 a, or 243 a, a second conductive type semiconductor layer 223 b, 233 b, or 243 b, and an active layer interposed therebetween. In particular, the active layer may have a multiple quantum well structure.

[0159] The closer the LED stack is to the substrate 241, the shorter the wavelength of light emitted from the LED stack. For example, the first LED stack 223 may be an inorganic light-emitting diode that emits red light, the second LED stack 233 may be an inorganic light-emitting diode that emits green light, and the third LED stack 243 may be an inorganic light-emitting diode that emits blue light. The first LED stack 223 may include a GaInP-based well layer, and the second LED stack 233 and the third LED stack 243 may include GaInN-based well layers. However, the inventive concept is not limited in this respect. If the light-emitting device 200 includes micro LEDs, the first LED stack 223 may emit any one of red, green, and blue light, and the second and third LED stacks 233 and 243 may emit the other one of red, green, and blue light without adversely affecting operation due to the small form factor of the micro LEDs.

[0160] The first conductivity type semiconductor layers 223a, 233a, and 243a of each of the LED stacks 223, 233, and 243 may be n-type semiconductor layers, and the second conductivity type semiconductor layers 223b, 233b, and 243b of each of the LED stacks 223, 233, and 243 may be p-type semiconductor layers. The top surface of the first LED stack 223 may be a p-type semiconductor layer 223b, the top surface of the second LED stack 233 may be an n-type semiconductor layer 233a, and the top surface of the third LED stack 243 may be a p-type semiconductor layer 243b. More specifically, according to an example embodiment, the order of the semiconductor layers is reversed only in the second LED stack 233. The first LED stack 223 and the third LED stack 243 may have first conductivity type semiconductor layers 223a and 243a with textured surfaces to improve light extraction efficiency. The second LED stack 233 may also have a first conductive type semiconductor layer 233a with a textured surface. However, because the first conductive type semiconductor layer 233a is disposed farther from the substrate 241 than the second conductive type semiconductor layer 233b, surface texturing is relatively less effective. More specifically, when the second LED stack 233 emits green light, the green light has higher visibility than red or blue light. Therefore, it is preferable to increase the luminous efficiency of the first LED stack 223 and the third LED stack 243 compared to the luminous efficiency of the second LED stack 233. In this manner, the luminous intensities of the red, green, and blue lights can be adjusted or balanced to be kept at similar levels by applying surface texturing to the first LED stack 223 and the third LED stack 243, thereby improving the light extraction efficiency while using a second LED stack 233 that is not surface-textured or has a small degree of surface texture.

[0161] In the first LED stack 223 and the third LED stack 243, the second conductive type semiconductor layers 223b and 243b are disposed on partial regions of the first conductive type semiconductor layers 223a and 243a, so that the first conductive type semiconductor layers 223a and 243a are partially exposed. Alternatively, in the second LED stack 233, the first conductive type semiconductor layer 233a and the second conductive type semiconductor layer 233b may completely overlap each other.

[0162] The first LED stack 223 is disposed apart from the substrate 241, the second LED stack 233 is disposed below the first LED stack 223, and the third LED stack 243 is disposed below the second LED stack 233. Because the first LED stack 223 can emit light having a longer wavelength than the second and third LED stacks 233 and 243, light generated from the first LED stack 223 is emitted to the outside through the second and third LED stacks 233 and 243 and the substrate 241. Also, because the second LED stack 233 can emit light having a longer wavelength than the third LED stack 243, light generated from the second LED stack 233 is emitted to the outside through the third LED stack 243 and the substrate 241. However, the concept of the present invention is not limited to this. For example, if the light emitting device 200 includes micro LEDs, the first LED stack 223 can emit any one of red, green, and blue light, and the second and third LED stacks 233 and 243 can emit any other one of red, green, and blue light without adversely affecting operation due to the small form factor of the micro LEDs.

[0163] The insulating layer 271 is disposed on the first LED stack 223 and has an opening for exposing the second conductive type semiconductor layer 223b of the first LED stack 223. The insulating layer 271 may have, for example, a substantially annular opening. The insulating layer 271 may be a transparent insulating layer having a refractive index lower than that of the first LED stack 223.

[0164] The first reflective electrode 228 is in ohmic contact with the second conductive type semiconductor layer 223b of the first LED stack 223 and reflects light generated in the first LED stack 223 toward the substrate 241. The first reflective electrode 228 is disposed on the insulating layer 271 and connected to the first LED stack 223 through an opening in the insulating layer 271.

[0165] The first reflective electrode 228 may include an ohmic contact layer 228a and a reflective layer 228b. The ohmic contact layer 228a is in partial contact with the second conductive type semiconductor layer 223b, for example, a p-type semiconductor layer. The ohmic contact layer 228a is formed within a predetermined area to prevent the ohmic contact layer 228a from absorbing light. The ohmic contact layer 228a is formed on the second conductive type semiconductor layer 223b exposed in the opening of the insulating layer 271. The ohmic contact layer 228a is formed to have a substantially annular shape. The ohmic contact layer 228a is formed of a transparent conductive oxide, for example, an Au alloy such as Au(Zn) or Au(Be).

[0166] The reflective layer 228b covers the ohmic contact layer 228a and the insulating layer 271. When the reflective layer 228b covers the insulating layer 271, the first LED stack 223 can have a stacked structure of the first LED stack 223 having a relatively high refractive index, the insulating layer 271 having a relatively low refractive index, and the reflective layer 228b. This stacked structure can form an omnidirectional reflector. The reflective layer 228b can include a reflective metal layer such as Al, Ag, or Au. The reflective layer 228b can also include an adhesive metal layer such as Ti, Ta, Ni, or Cr on the upper and lower surfaces of the reflective metal layer to improve adhesion of the reflective metal layer. Gold (Au) is particularly suitable for the reflective layer 228b formed in the first LED stack 223 due to its high reflectivity for red light and low reflectivity for blue or green light. The reflective layer 228b can cover about 50% or more of the area of ​​the first LED stack 223, and can also cover most of the area to improve light efficiency.

[0167] The ohmic contact layer 228a and the reflective layer 228b are formed of a metal layer containing gold (Au). The reflective layer 228b is formed of a metal layer having a high reflectivity for light, for example, red light, generated in the first LED stack 223. The reflective layer 228b may have a relatively low reflectivity for light, for example, green light or blue light, generated in the second LED stack 233 and the third LED stack 243. Therefore, the light generated in the second and third LED stacks 233 and 243 and incident on the reflective layer 228b may be absorbed, reducing optical interference.

[0168] The first ohmic electrode 226 is disposed on the exposed first conductivity type semiconductor layer 223a and makes ohmic contact with the first conductivity type semiconductor layer 223a. The first ohmic electrode 226 is further formed of a metal layer containing gold (Au).

[0169] The second transparent electrode 235 is in ohmic contact with the second conductivity type semiconductor layer 233b of the second LED stack 233. As shown, the second transparent electrode 235 is in contact with the lower surface of the second LED stack 233 between the second LED stack 233 and the third LED stack 243. The second transparent electrode 235 is formed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0170] Additionally, the third transparent electrode 245 makes ohmic contact with the second conductive type semiconductor layer 243b of the third LED stack 243. The third transparent electrode 245 is disposed between the second LED stack 233 and the third LED stack 243 and contacts the top surface of the third LED stack 243. The third transparent electrode 245 is formed of a metal layer or a conductive oxide layer that is transparent to red and green light. In some exemplary embodiments, the third transparent electrode 245 may also be transparent to blue light. The second transparent electrode 235 and the third transparent electrode 245 can aid current spreading through ohmic contact with the p-type semiconductor layer of each LED stack. Examples of conductive oxide layers used for the second and third transparent electrodes 235 and 245 include SnO2, InO2, ITO, ZnO, IZO, etc.

[0171] The first color filter 247 is disposed between the third transparent electrode 245 and the second LED stack 233, and the second color filter 267 is disposed between the second LED stack 233 and the first LED stack 223. The first color filter 247 can transmit light generated in the first and second LED stacks 223 and 233 and can reflect light generated in the third LED stack 243. The second color filter 267 can transmit light generated in the first LED stack 223 and can reflect light generated in the second LED stack 233. Therefore, the light generated in the first LED stack 223 is emitted to the outside via the second LED stack 233 and the third LED stack 243, and the light generated in the second LED stack 233 is emitted to the outside via the third LED stack 243. In addition, light generated in the second LED stack 233 can be prevented from being incident on the first LED stack 223 and being lost, and light generated in the third LED stack 243 can be prevented from being incident on the second LED stack 233 and being lost.

[0172] In some exemplary embodiments, the second color filter 267 can reflect the light generated by the third LED stack 243 .

[0173] The first and second color filters 247 and 267 may be low-frequency filters, such as low-pass filters that pass only long wavelength bands, band-pass filters that pass only a predetermined wavelength band, or band-stop filters that block only a predetermined wavelength band. In particular, the first and second color filters 247 and 267 can be formed by alternately stacking insulating layers with different refractive indices, such as by alternately stacking TiO2 insulating layers and SiO2 insulating layers. In particular, the first and second color filters 247 and 267 can include a distributed Bragg reflector (DBR). The stopband of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2 layers. Low-pass and band-pass filters can also be formed by alternately stacking insulating layers with different refractive indices.

[0174] The first bonding layer 249 bonds the second LED stack 233 to the third LED stack 243. The first bonding layer 249 covers the first color filter 247 and is bonded to the second transparent electrode 235. For example, the first bonding layer 249 may be a transparent organic layer or a transparent inorganic layer. Examples of organic layers include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, and benzocyclobutene (BCB), while examples of inorganic layers include Al2O3, SiO2, SiN x Organic layers may be bonded under high vacuum and pressure, and inorganic layers may be bonded under high vacuum with reduced surface energy, for example using plasma, after planarizing the surface using, for example, a chemical mechanical polishing process.

[0175] The second bonding layer 269 couples the second LED stack 233 to the first LED stack 223. As shown, the second bonding layer 269 can cover the second color filter 267 and can be in contact with the first LED stack 223. However, the concept of the present invention is not limited in this respect, and another layer, such as a transparent electrode layer, can be further disposed on the lower surface of the first LED stack 223. The second bonding layer 269 can be formed of substantially the same material as the first bonding layer 249 described above.

[0176] The upper insulating layer 273 covers the side and top portions of the first, second, and third LED stacks 223, 233, and 243. The upper insulating layer 273 is formed of SiO2, Si3N4, SOG, or the like. Alternatively, the upper insulating layer 273 may include a light-reflecting or light-blocking material to prevent optical interference with adjacent light-emitting devices. For example, the upper insulating layer 273 may include a distributed Bragg reflector that reflects red, green, and blue light, or a SiO2 layer having a reflective metal layer or a highly reflective organic layer deposited thereon. Alternatively, the upper insulating layer 273 may include, for example, black epoxy as a light-blocking material. The light-blocking material increases image contrast by preventing optical interference between light-emitting devices.

[0177] The upper insulating layer 273 has openings to expose the first ohmic electrode 226, the first reflective electrode 228, the second and third transparent electrodes 235 and 245, and the second and third LED stacks 233 and 243. Holes are formed to penetrate the first LED stack 223 and the second LED stack 233, and the upper insulating layer 273 can cover the sidewalls of the holes while exposing the bottom surfaces of the holes.

[0178] The electrode pads 281a, 281b, 281c, and 281d are disposed on the top of the first LED stack 223 and are electrically connected to the first, second, and third LED stacks 223, 233, and 243. The electrode pads 281a, 281b, 281c, and 281d are disposed on the upper insulating layer 273 and are connected to the first ohmic electrode 226, the first reflective electrode 228, the second and third transparent electrodes 235 and 245, and the second and third LED stacks 233 and 243 exposed through holes h1, h2, h3, h4, and h5.

[0179] For example, the first electrode pad 281a is connected to the first ohmic electrode 226 through a hole h4 that penetrates the upper insulating layer 273. The first electrode pad 281a is electrically connected to the first conductivity type semiconductor layer 223a of the first LED stack 223.

[0180] The second electrode pad 281b is connected to the first conductivity type semiconductor layer 233a of the second LED stack 233 via a hole h3 that passes through the upper insulating layer 273 and the first LED stack 223.

[0181] The third electrode pad 281c is electrically connected to the first conductivity type semiconductor layer 243a of the third LED stack 243 via a hole h2 that penetrates the upper insulating layer 273, the first LED stack 223, and the second LED stack 233. The hole h2 can penetrate the second conductivity type semiconductor layer 243b and the active layer of the third LED stack 243.

[0182] On the other hand, the common electrode pad 281d is commonly connected to the first reflective electrode 228, the second transparent electrode 235, and the third transparent electrode 245 via holes h1 and h5. The hole h1 penetrates the first LED stack 223 and the second LED stack 233 to expose the second transparent electrode 235 and the third transparent electrode 245, and the hole h5 exposes the first reflective electrode 228. Therefore, the common electrode pad 281d is commonly electrically connected to the second conductive type semiconductor layer 223b of the first LED stack 223, the second conductive type semiconductor layer 233b of the second LED stack 233, and the second conductive type semiconductor layer 243b of the third LED stack 243. In addition, as shown in FIG. 21B , the common electrode pad 281d is connected to the third LED stack 243 via a hole h1 that penetrates a hollow portion surrounded by the first reflective electrode 228.

[0183] According to an exemplary embodiment, the first LED stack 223 is electrically connected to the electrode pads 281d and 281a, the second LED stack 233 is electrically connected to the electrode pads 281d and 281b, and the third LED stack 243 is electrically connected to the electrode pads 281d and 281c. Therefore, the anodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243 are commonly electrically connected to the electrode pad 281d, and the cathodes thereof are electrically connected to the first, second, and third electrode pads 281a, 281b, and 281c, respectively. Therefore, the first, second, and third LED stacks 223, 233, and 243 can be driven independently.

[0184] 22, 23, 24, 25, 26A, 26B, 27A, 27B, 28A, 28B, 29, 30A, 30B, 31A, 31B, 32A, 32B, 33A, 33B, 34A, 34B, 35A, and 35B are schematic plan views and cross-sectional views illustrating a method of fabricating a light-emitting device 200 according to an illustrative embodiment, where each plan view corresponds to the plan view of FIG. 21A and each cross-sectional view is taken along line AA of FIG. 21A.

[0185] 22, a first LED stack 223 is grown on a first substrate 221. The first substrate 221 may be, for example, a GaAs substrate. The first LED stack 223 is formed of an AlGaInP-based semiconductor layer and includes a first conductivity type semiconductor layer 223a, an active layer, and a second conductivity type semiconductor layer 223b. The first conductivity type may be n-type, and the second conductivity type may be p-type.

[0186] 23, a second LED stack 233 is grown on a second substrate 231, and a second transparent electrode 235 is formed on the second LED stack 233. The second LED stack 233 is formed of a gallium nitride-based semiconductor layer and may include a first conductivity type semiconductor layer 233a, an active layer, and a second conductivity type semiconductor layer 233b. The active layer may include a GaInN well layer. The first conductivity type may be n-type, and the second conductivity type may be p-type.

[0187] The second substrate 231 is a substrate on which a gallium nitride-based semiconductor layer can be grown and is different from the first substrate 221. The composition ratio of the GaInN well layer may be determined so that the second LED stack 233 emits, for example, green light. The second transparent electrode 235 is in ohmic contact with the second conductivity type semiconductor layer 233b. The second transparent electrode 235 is formed of a conductive oxide layer such as SnO2, InO2, ITO, ZnO, or IZO.

[0188] 24 , a third LED stack 243 is grown on a third substrate 241, and a third transparent electrode 245 and a first color filter 247 are formed on the third LED stack 243. The third LED stack 243 is formed of a gallium nitride-based semiconductor layer and includes a first conductivity type semiconductor layer 243a, an active layer, and a second conductivity type semiconductor layer 243b. The active layer may further include a GaInN well layer. The first conductivity type may be n-type, and the second conductivity type may be p-type.

[0189] The third substrate 241 is a substrate on which a gallium nitride-based semiconductor layer can be grown and is different from the first substrate 221. The composition ratio of the GaInN well layer may be determined so that the third LED stack 243 emits, for example, blue light. The third transparent electrode 245 is in ohmic contact with the second conductivity type semiconductor layer 243b. The third transparent electrode 245 is formed of a conductive oxide layer such as SnO2, InO2, ITO, ZnO, or IZO.

[0190] The first color filter 247 is substantially the same as that described with reference to FIGS. 21A and 21B, and therefore a detailed description thereof will be omitted to avoid redundancy.

[0191] Referring to FIG. 25, the second LED stack 233 of FIG. 23 is bonded onto the third LED stack 243 of FIG.

[0192] The first color filter 247 and the second transparent electrode 235 are bonded to face each other. For example, a bonding material layer is formed on the first color filter 247 and the second transparent electrode 235, respectively, and the first color filter 247 and the second transparent electrode 235 are bonded together to form the first bonding layer 249. The bonding material layer may be, for example, a transparent organic layer or a transparent inorganic layer. Examples of the organic layer include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc., and examples of the inorganic layer include Al2O3, SiO2, SiN x Organic layers may be bonded under high vacuum and pressure, and inorganic layers may be bonded under high vacuum with reduced surface energy, for example using plasma, after planarizing the surface using, for example, a chemical mechanical polishing process.

[0193] Thereafter, the second substrate 231 is removed from the second LED stack 233 using a technique such as laser lift-off or chemical lift-off, thereby exposing the first conductive type semiconductor layer 233a of the second LED stack 233 from the top. The exposed surface of the first conductive type semiconductor layer 233a is textured.

[0194] Meanwhile, before bonding the first LED stack 223 to the second LED stack 233, a reflective electrode and an ohmic electrode are first formed on the first LED stack 223, and the substrate 221 is removed using a carrier substrate, which will be described in more detail below with reference to Figures 26A, 26B, 27A, 27B, 28A, 28B, and 29.

[0195] 26A and 26B, the second conductivity type semiconductor layer 223b of the first LED stack 223 of FIG. 22 is patterned to expose the first conductivity type semiconductor layer 223a. The light emitting device region may have a substantially rectangular shape as shown in FIG. 26A. The second conductivity type semiconductor layer 223b is removed near four corners within one light emitting device region. As shown in FIG. 26A, the second conductivity type semiconductor layer 223b may be removed near all three corners, or a hole penetrating the second conductivity type semiconductor layer 223b may be formed near one corner. Although one light emitting device region is shown, multiple light emitting device regions may be provided on the substrate 241, and according to some illustrative embodiments, the second conductivity type semiconductor layer 223b may be patterned in each light emitting device region.

[0196] 27A and 27B, a first ohmic electrode 226 is formed near one corner and makes ohmic contact with the first conductive type semiconductor layer 223a.

[0197] Thereafter, an insulating layer 271 covering the first ohmic electrode 226 and the first LED stack 223 is formed and patterned to form an opening that exposes the second conductive type semiconductor layer 223b. For example, SiO2 is formed on the first LED stack 223, a photoresist is applied, and then a photoresist pattern is formed using photolithography and development. Then, the SiO2 is patterned using the photoresist pattern as an etching mask to form the insulating layer 271 with an opening.

[0198] The opening is formed around the hole that penetrates the second conductivity type semiconductor layer 223b, and can surround the hole that has a substantially annular shape.

[0199] Thereafter, the ohmic contact layer 228a is formed in the opening of the insulating layer 271. The ohmic contact layer 228a is formed by using a lift-off method or the like. The ohmic contact layer 228a is formed to have a substantially annular shape that follows the shape of the opening.

[0200] 28A and 28B, after the ohmic contact layer 228a is formed, a reflective layer 228b is formed to cover the ohmic contact layer 228a and the insulating layer 271. The reflective layer 228b is formed using a lift-off method or the like. The first reflective electrode 228 is formed by the ohmic contact layer 228a and the reflective layer 228b.

[0201] The first reflective electrode 228 may have a shape in which four corners of one rectangular light emitting device region are removed, as shown. In particular, at one corner, the first reflective electrode 228 may have a hollow portion above a hole formed in the second conductivity type semiconductor layer 223b. Although one light emitting device region is shown, multiple light emitting device regions may be provided on the substrate 221, and according to some example embodiments, the first reflective electrode 228 may be formed in each light emitting device region.

[0202] 29, a carrier substrate 251 is bonded onto the first LED stack 223 of FIGS. 28A and 28B. The first reflective electrode 228 may be arranged facing the carrier substrate 251, and the first LED stack 223 may be bonded to the carrier substrate 251 using an adhesive layer 253. The substrate 221 is then removed from the first LED stack 223, thereby exposing the first conductive type semiconductor layer 223a. The exposed surface of the first conductive type semiconductor layer 223a is textured to improve light extraction efficiency, and a roughened surface or light extraction structure is formed on the surface of the first conductive type semiconductor layer 223a.

[0203] A method of manufacturing a light emitting device 200 by bonding a first LED stack 223 onto a second LED stack 233 will now be described with reference to FIG.

[0204] 30A and 30B, first, a second color filter 267 is formed on the exposed first conductive type semiconductor layer 233a of the second LED stack 233 of Fig. 25. The second color filter 267 is substantially the same as that described with reference to Figs. 21A and 21B, and therefore a detailed description thereof will be omitted.

[0205] The first LED stack 223 is bonded onto the second LED stack 233. The second color filter 267 and the first LED stack 223 may be bonded facing each other. For example, a bonding material layer is formed on the second color filter 267 and the first LED stack 223, respectively, and the second color filter 267 and the first LED stack 223 are bonded together to form a second bonding layer 269. The bonding material layer may be a transparent organic layer or a transparent inorganic layer, as described above.

[0206] The carrier substrate 251 and the adhesive layer 253 are then removed, thus exposing the first reflective electrode 228.

[0207] 31A and 31B , the insulating layer 271 is patterned to expose the first LED stack 223 around the first reflective electrode 228. Then, the first LED stack 223, the second bonding layer 269, and the second color filter 269 are sequentially patterned to form holes h1, h2, and h3 that penetrate and expose the first conductive type semiconductor layer 233a of the second LED stack 233. The second LED stack 233 is also patterned, and holes h1 and h2 penetrate the second LED stack 233 to expose the second transparent electrode 235. Hole h3 is maintained to expose the first conductive type semiconductor layer 233a of the second LED stack 233.

[0208] Additionally, the insulating layer 271, the first LED stack 223, the second bonding layer 269, the second color filter 267 and the second LED stack 233 are sequentially removed to expose the second transparent electrode 235 at the peripheral portion of the light emitting device area.

[0209] 32A and 32B, the second transparent electrode 235, the first bonding layer 249, and the first color filter 247 are removed to expose the third transparent electrode 245 through holes h1 and h2. The top surface of the second transparent electrode 235 is partially exposed within the hole h1.

[0210] In addition, second transparent electrode 235 , first bonding layer 249 and first color filter 247 are also removed at the peripheral portion of the light emitting device area to expose third transparent electrode 245 .

[0211] 33A and 33B, the third transparent electrode 245 and the second conductive type semiconductor layer 243b are patterned to expose the first conductive type semiconductor layer 243a of the third LED stack 243 through the hole h2, and the hole h1 is retained to expose the third transparent electrode 245.

[0212] Additionally, the third transparent electrode 245 and the third LED stack 243 are removed so that the substrate 241 is exposed at the peripheral portion of the light emitting device region. The exposed region of the substrate 241 may be a dicing region for dividing the light emitting devices.

[0213] 33B, hole h1 is formed to penetrate the hollow portion of first reflective electrode 228, exposing second transparent electrode 235 and third transparent electrode 245. Hole h2 penetrates all of first and second LED stacks 223 and 233, penetrating second conductivity type semiconductor layer 243b and thereby exposing first conductivity type semiconductor layer 243a. Hole h3 penetrates first LED stack 223 and exposes first conductivity type semiconductor layer 233a of second LED stack 233.

[0214] 34A and 34B, an upper insulating layer 273 is formed to cover the side and upper regions of the first, second, and third LED stacks 223, 233, and 243. The upper insulating layer 273 may be formed of a single layer or multiple layers of SiO2, Si3N4, SOG, etc. Alternatively, the upper insulating layer 273 may include a light-reflecting or light-blocking material to prevent optical interference between adjacent light-emitting devices. For example, the upper insulating layer 273 may include a distributed Bragg reflector that reflects red, green, and blue light, or a SiO2 layer having a reflective metal layer or a highly reflective organic layer deposited thereon. Alternatively, the upper insulating layer 273 may include, for example, black epoxy as a light-blocking material. The light-blocking material may increase image contrast by preventing optical interference between light-emitting devices. The distributed Bragg reflector may be formed, for example, by alternately depositing SiO2 and TiO2 layers.

[0215] Thereafter, the upper insulating layer 273 is patterned using photolithography and etching to form openings in the holes h1, h2, and h3, and further to form holes h4 and h5. The upper insulating layer 273 exposes the second transparent electrode 235 and the third transparent electrode 245 in the hole h1 and covers the side surfaces of the first LED stack 223 and the second LED stack 233. The upper insulating layer 273 also covers the sidewalls of the hole h2 while exposing the first conductive type semiconductor layer 243a. The upper insulating layer 273 also exposes the first conductive type semiconductor layer 233a of the second LED stack 233 in the hole h3. Meanwhile, the hole h4 penetrates the upper insulating layer 273 and the insulating layer 271 to expose the first ohmic electrode 226, and the hole h5 penetrates the upper insulating layer 273 to expose the first reflective electrode 228. The hole h5 is formed to have a substantially annular shape, as shown in FIG. 34A .

[0216] 35A and 35B, electrode pads 281a, 281b, 281c, and 281d are formed on the upper insulating layer 273. The electrode pads 281a, 281b, 281c, and 281d include a first electrode pad 281a, a second electrode pad 281b, a third electrode pad 281c, and a common electrode pad 281d.

[0217] The common electrode pad 281d is connected to the second transparent electrode 235 and the third transparent electrode 245 through the hole h1, and is connected to the first reflective electrode 228 through the hole h5. Therefore, the common electrode pad 281d is commonly and electrically connected to the anodes of the first, second, and third LED stacks 223, 233, and 243.

[0218] The first electrode pad 281a is connected to the first ohmic electrode 226 via a hole h4 and is electrically connected to the cathode of the first LED stack 223, for example, the first conductivity type semiconductor layer 223a. Meanwhile, the second electrode pad 281b is electrically connected to the cathode of the second LED stack 233, for example, the first conductivity type semiconductor layer 233a, via a hole h3, and the third electrode pad 281c is electrically connected to the cathode of the third LED stack 243, for example, the first conductivity type semiconductor layer 243a, via a hole h2.

[0219] Meanwhile, the electrode pads 281a, 281b, 281c and 281d are electrically isolated from each other, and the first, second and third LED stacks 223, 233 and 243 are adapted to be electrically connected to two electrode pads and driven independently, respectively.

[0220] Subsequently, the light emitting devices 200 according to the illustrative embodiment are provided by dividing the substrate 241 into light emitting device regions. As shown in Fig. 35A, electrode pads 281a, 281b, 281c, and 281d are disposed at the four corners of each light emitting device 200. In addition, the electrode pads 281a, 281b, 281c, and 281d may have a substantially rectangular shape, but are not limited thereto.

[0221] Although the substrate 241 has been described as being separated, according to some example embodiments, the substrate 241 can be removed so that the exposed surface of the first conductivity type semiconductor layer 243a can be textured. The substrate 241 can be removed after bonding the first LED stack 223 onto the second LED stack 233, or after forming the electrode pads 281a, 281b, 281c, and 281d.

[0222] According to an exemplary embodiment, the light emitting device includes anodes of the first, second, and third LED stacks 223, 233, and 243 that are electrically connected in common, and cathodes thereof that are independently connected. However, the concept of the present invention is not limited thereto, and for example, the anodes of the first, second, and third LED stacks 223, 233, and 243 may be independently connected to electrode pads, and cathodes thereof may be electrically connected in common.

[0223] The light-emitting device 200 includes first, second, and third LED stacks 223, 233, and 243 and can emit red, green, and blue light, and thus can be used as a single pixel in a display device. As described with reference to FIG. 20 , a display device is provided by arranging multiple light-emitting devices 200 on a circuit board 201. Because the light-emitting device 200 includes the first, second, and third LED stacks 223, 233, and 243, the area of ​​the subpixels within one pixel can be increased. In addition, the first, second, and third LED stacks 223, 233, and 243 can be mounted by mounting one light-emitting device 200, thereby reducing the number of mounting steps.

[0224] As described with reference to FIG. 20, a light emitting device 200 mounted on a circuit board 201 can be driven by a passive matrix method or an active matrix method.

[0225] FIG. 36 is a schematic cross-sectional view of a light emitting diode stack for a display according to an example embodiment.

[0226] 36, the light emitting diode stack 1000 includes a support substrate 1510, a first LED stack 1230, a second LED stack 1330, a third LED stack 1430, a reflective electrode 1250, an ohmic electrode 1290, a second-p transparent electrode 1350, a third-p transparent electrode 1450, an insulating layer 1270, a first color filter 1370, a second color filter 1470, a first bonding layer 1530, a second bonding layer 1550, and a third bonding layer 1570. The first LED stack 1230 may also include an ohmic contact portion 1230a for ohmic contact.

[0227] Support substrate 1510 supports semiconductor stacks 1230, 1330, and 1430. Support substrate 1510 may include circuitry on or within its surface, although the inventive concept is not limited in this respect. Support substrate 1510 may include, for example, a Si substrate or a Ge substrate.

[0228] Each of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multi-quantum well structure.

[0229] For example, first LED stack 1230 may be an inorganic light emitting diode configured to emit red light, second LED stack 1330 may be an inorganic light emitting diode configured to emit green light, and third LED stack 1430 may be an inorganic light emitting diode configured to emit blue light. First LED stack 1230 may include a GaInP-based well layer, and second LED stack 1330 and third LED stack 1430 may each include a GaInN-based well layer.

[0230] At the same time, both surfaces of each of the first to third LED stacks 1230, 1330, and 1430 are n-type and p-type semiconductor layers, respectively. In the illustrated exemplary embodiment, each of the first to third LED stacks 1230, 1330, and 1430 has an n-type upper surface and a p-type lower surface. Because the third LED stack 1430 has an n-type upper surface, a roughened surface is formed on the upper surface of the third LED stack 1430 by chemical etching. However, the concept of the present invention is not limited in this respect, and the semiconductor types of the upper and lower surfaces of each LED stack may be alternatively arranged.

[0231] The first LED stack 1230 is disposed near the support substrate 1510, the second LED stack 1330 is disposed on the first LED stack 1230, and the third LED stack 1430 is disposed on the second LED stack 1330. Because the first LED stack 1230 emits light having a longer wavelength than the second and third LED stacks 1330 and 1430, light generated from the first LED stack 1230 is emitted to the outside via the second and third LED stacks 1330 and 1430. Also, because the second LED stack 1330 emits light having a longer wavelength than the third LED stack 1430, light generated from the second LED stack 1330 is emitted to the outside via the third LED stack 1430.

[0232] The reflective electrode 1250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 1230 and reflects light generated from the first LED stack 1230. For example, the reflective electrode 1250 may include an ohmic contact layer 1250a and a reflective layer 1250b.

[0233] The ohmic contact layer 1250a partially contacts the p-type semiconductor layer of the first LED stack 1230. To prevent light absorption by the ohmic contact layer 1250a, the area where the ohmic contact layer 1250a contacts the p-type semiconductor layer may not exceed 50% of the entire area of ​​the p-type semiconductor layer. The reflective layer 1250b covers the ohmic contact layer 1250a and the insulating layer 1270. As shown in FIG. 36, the reflective layer 1250b can cover substantially the entire ohmic contact layer 1250a, but is not limited to this. Alternatively, the reflective layer 1250b can cover only a portion of the ohmic contact layer 1250a.

[0234] Because the reflective layer 1250b covers the insulating layer 1270, an omnidirectional reflector is formed by the stacked structure of the first LED stack 1230, which has a relatively high refractive index, the insulating layer 1270, which has a relatively low refractive index, and the reflective layer 1250b. The reflective layer 1250b covers 50% or more of the area of ​​the first LED stack 1230 or most of the first LED stack 1230, thereby improving the light-emitting efficiency.

[0235] The ohmic contact layer 1250a and the reflective layer 1250b may be metal layers that may include gold (Au). The reflective layer 1250b is formed of a metal that has a relatively high reflectivity for light generated from the first LED stack 1230, for example, red light. On the other hand, the reflective layer 1250b is formed of a metal that has a relatively low reflectivity for light generated from the second LED stack 1330 and the third LED stack 1430, for example, green light or blue light, and can reduce interference of light generated from the second and third LED stacks 1330 and 1430 and traveling toward the support substrate 1510.

[0236] The insulating layer 1270 is interposed between the support substrate 1510 and the first LED stack 1230 and has an opening exposing the first LED stack 1230. The ohmic contact layer 1250a is connected to the first LED stack 1230 within the opening of the insulating layer 1270.

[0237] An ohmic electrode 1290 is disposed on the upper surface of the first LED stack 1230. To reduce the ohmic contact resistance of the ohmic electrode 1290, an ohmic contact portion 1230a may protrude from the upper surface of the first LED stack 1230. The ohmic electrode 1290 is disposed on the ohmic contact portion 1230a.

[0238] The second-p transparent electrode 1350 forms an ohmic contact with the p-type semiconductor layer of the second LED stack 1330. The second-p transparent electrode 1350 can include a metal layer or a conductive oxide layer that is transparent to red and green light.

[0239] The third-p transparent electrode 1450 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 1430. The third-p transparent electrode 1450 can include a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0240] The reflective electrode 1250, the second-p transparent electrode 1350 and the third-p transparent electrode 1450 can help current spreading by making ohmic contact with the p-type semiconductor layers of the corresponding LED stacks.

[0241] The first color filter 1370 may be interposed between the first LED stack 1230 and the second LED stack 1330. The second color filter 1470 may be interposed between the second LED stack 1330 and the third LED stack 1430. The first color filter 1370 transmits light generated from the first LED stack 1230 while reflecting light generated from the second LED stack 1330. The second color filter 1470 transmits light generated from the first and second LED stacks 1230 and 1330 while reflecting light generated from the third LED stack 1430. In this manner, the light generated from the first LED stack 1230 is emitted to the outside via the second LED stack 1330 and the third LED stack 1430, and the light generated from the second LED stack 1330 is emitted to the outside via the third LED stack 1430. In addition, light generated from the second LED stack 1330 can be prevented from flowing into the first LED stack 1230, and light generated from the third LED stack 1430 can be prevented from flowing into the second LED stack 1330, thereby preventing light loss.

[0242] In some demonstrative embodiments, the first color filter 1370 can reflect the light generated from the third LED stack 1430 .

[0243] The first and second color filters 1370 and 1470 may be, for example, low-pass filters that transmit light in a low frequency band (i.e., a long wavelength band), band-pass filters that transmit light in a predetermined wavelength band, or band-stop filters that prevent light from passing in a predetermined wavelength band. In particular, each of the first and second color filters 1370 and 1470 may include a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers with different refractive indices, such as TiO2 and SiO2. At the same time, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2 layers. Low-pass and band-pass filters can also be formed by alternately stacking insulating layers with different refractive indices.

[0244] A first bonding layer 1530 bonds the first LED stack 1230 to the support substrate 1510. As shown in Figure 36, a reflective electrode 1250 may be adjacent to the first bonding layer 1530. The first bonding layer 1530 may be a light-transmitting or opaque layer.

[0245] A second bonding layer 1550 couples the second LED stack 1330 to the first LED stack 1230. As shown in FIG. 36 , the second bonding layer 1550 may be adjacent to the first LED stack 1230 and the first color filter 1370. The ohmic electrode 1290 may be covered by the second bonding layer 1550. The second bonding layer 1550 transmits light generated from the first LED stack 1230. The second bonding layer 1550 may be formed of, for example, light transmissive spin-on-glass.

[0246] The third bonding layer 1570 bonds the third LED stack 1430 to the second LED stack 1330. As shown in FIG. 36 , the third bonding layer 1570 may be adjacent to the second LED stack 1330 and the second color filter 1470. However, the concept of the present invention is not limited in this respect. For example, a transparent conductive layer may be disposed on the second LED stack 1330. The third bonding layer 1570 transmits light generated from the first LED stack 1230 and the second LED stack 1330. The third bonding layer 1570 may be formed of, for example, light-transmitting spin-on glass.

[0247] 37A, 37B, 37C, 37D, and 37E are schematic cross-sectional views illustrating a method of fabricating a light emitting diode stack for a display according to an example embodiment.

[0248] 37A, a first LED stack 1230 is grown on a first substrate 1210. The first substrate 1210 may be, for example, a GaAs substrate. The first LED stack 1230 is formed of an AlGaInP-based semiconductor layer and includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0249] An insulating layer 1270 is formed on the first LED stack 1230 and patterned to form an opening. For example, a SiO layer is formed on the first LED stack 1230, and a photoresist is deposited on the SiO layer, followed by photolithography and development to form a photoresist pattern. The SiO layer is then patterned through the photoresist pattern used as an etching mask, thereby forming the insulating layer 1270.

[0250] Then, an ohmic contact layer 1250a is formed in the opening of the insulating layer 1270. The ohmic contact layer 1250a is formed by a lift-off process or the like. After the ohmic contact layer 1250a is formed, a reflective layer 1250b is formed to cover the ohmic contact layer 1250a and the insulating layer 1270. The reflective layer 1250b is formed by a lift-off process or the like. The reflective layer 1250b can cover a portion of the ohmic contact layer 1250a or the entire ohmic contact layer 1250a, as shown in FIG. 37A . The ohmic contact layer 1250a and the reflective layer 1250b form a reflective electrode 1250.

[0251] The reflective electrode 1250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 1230 , and is therefore hereinafter referred to as the first-p reflective electrode 1250 .

[0252] 37B , a second LED stack 1330 is grown on a second substrate 1310, and a second-p transparent electrode 1350 and a first color filter 1370 are formed on the second LED stack 1330. The second LED stack 1330 is formed of a GaN-based semiconductor layer and may include a GaInN well layer. The second substrate 1310 is a substrate on which a GaN-based semiconductor layer can be grown and is different from the first substrate 1210. The composition ratio of GaInN for the second LED stack 1330 may be determined so that the second LED stack 1330 emits green light. The second-p transparent electrode 1350 forms ohmic contact with the p-type semiconductor layer of the second LED stack 1330.

[0253] 37C , a third LED stack 1430 is grown on a third substrate 1410, and a third-p transparent electrode 1450 and a second color filter 1470 are formed on the third LED stack 1430. The third LED stack 1430 is formed of a GaN-based semiconductor layer and may include a GaInN well layer. The third substrate 1410 is a substrate on which a GaN-based semiconductor layer can be grown and is different from the first substrate 1210. The composition ratio of GaInN for the third LED stack 1430 may be determined so that the third LED stack 1430 emits blue light. The third-p transparent electrode 1450 forms ohmic contact with the p-type semiconductor layer of the third LED stack 1430.

[0254] The first color filter 1370 and the second color filter 1470 are substantially the same as those described with reference to FIG. 36, and therefore a repeated description will be omitted to avoid redundancy.

[0255] In this manner, the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 may be grown on different substrates, and the order of their formation is not limited to any particular order.

[0256] 37D , the first LED stack 1230 is bonded to the support substrate 1510 via a first bonding layer 1530. The first bonding layer 1530 may be pre-formed on the support substrate 1510, and the reflective electrode 1250 may be bonded to the first bonding layer 1530 so as to face the support substrate 1510. The first substrate 1210 is removed from the first LED stack 1230 by chemical etching or the like. Thus, the top surface of the n-type semiconductor layer of the first LED stack 1230 is exposed.

[0257] Then, an ohmic electrode 1290 is formed on the exposed area of ​​the first LED stack 1230. The ohmic electrode 1290 is subjected to a heat treatment to reduce the ohmic contact resistance of the ohmic electrode 1290. The ohmic electrode 1290 is formed on each pixel area so as to correspond to the pixel area.

[0258] 37E , the second LED stack 1330 is coupled to the first LED stack 1230, on which the ohmic electrode 1290 is formed, via a second bonding layer 1550. The first color filter 1370 is bonded to the second bonding layer 1550 facing the first LED stack 1230. The second bonding layer 1550 may be pre-formed on the first LED stack 1230 so that the first color filter 1370 can be bonded to the second bonding layer 1550 facing the second bonding layer 1550. The second substrate 1310 is separated from the second LED stack 1330 by a laser lift-off or chemical lift-off process.

[0259] 36 and 37C , the third LED stack 1430 is coupled to the second LED stack 1330 via the third bonding layer 1570. The second color filter 1470 is bonded to the third bonding layer 1570 so as to face the second LED stack 1330. The third bonding layer 1570 may be pre-positioned on the second LED stack 1330 so that the second color filter 1470 can be bonded to the third bonding layer 1570 so as to face the third bonding layer 1570. The third substrate 1410 is separated from the third LED stack 1430 by a laser lift-off or chemical lift-off process. In this way, a light-emitting diode stack for a display is formed as shown in FIG. 36 , with the n-type semiconductor layer of the third LED stack 1430 exposed to the outside.

[0260] The display device according to the exemplary embodiment is provided by patterning a stack of first to third LED stacks 1230, 1330 and 1430 on a support substrate 1510 in a pixel unit, and then the first to third LED stacks are connected to each other by interconnections. The display device according to the exemplary embodiment will be described below.

[0261] FIG. 38 is a schematic circuit diagram of a display device according to an exemplary embodiment, and FIG. 39 is a schematic plan view of a display device according to an exemplary embodiment.

[0262] Referring to Figures 38 and 39, the display device according to the exemplary embodiment can operate in a passive matrix manner.

[0263] 36 includes first to third LED stacks 1230, 1330, and 1430 stacked vertically, so that one pixel can include three light emitting diodes R, G, and B. The first light emitting diode R can correspond to the first LED stack 1230, the second light emitting diode G can correspond to the second LED stack 1330, and the third light emitting diode B can correspond to the third LED stack 1430.

[0264] 38 and 39, one pixel includes first to third light-emitting diodes R, G, and B, each of which corresponds to a subpixel. The anodes of the first to third light-emitting diodes R, G, and B are connected to a common line, e.g., a data line, and the cathodes are connected to different lines, e.g., scan lines. More specifically, in the first pixel, the anodes of the first to third light-emitting diodes R, G, and B are commonly connected to the data line Vdata1, and the cathodes are connected to the scan lines Vscan1-1, Vscan1-2, and Vscan1-3, respectively. In this way, the light-emitting diodes R, G, and B in each pixel can be driven independently.

[0265] Additionally, each of the light emitting diodes R, G and B can be driven by pulse width modulation or by varying the magnitude of the current, thereby controlling the brightness of each sub-pixel.

[0266] 39, a plurality of pixels are formed by patterning the light emitting diode stack 1000 of FIG. 36, and each pixel is connected to a reflective electrode 1250 and interconnection lines 1710, 1730, and 1750. As shown in FIG. 38, the reflective electrode 1250 can be used as a data line Vdata, and the interconnection lines 1710, 1730, and 1750 can be formed as scan lines.

[0267] The pixels are arranged in a matrix, with the anodes of the light-emitting diodes R, G, and B of each pixel commonly connected to the reflective electrode 1250, and the cathodes connected to interconnection lines 1710, 1730, and 1750 that are separated from each other. Here, the interconnection lines 1710, 1730, and 1750 can be used as scan lines Vscan.

[0268] 40 is an enlarged plan view of one pixel of the display device of FIG. 39, FIG. 41 is a schematic cross-sectional view taken along line AA in FIG. 40, and FIG. 42 is a schematic cross-sectional view taken along line BB in FIG. 40.

[0269] Referring to Figures 39, 40, 41 and 42, in each pixel, a portion of the reflective electrode 1250, an ohmic electrode 1290 formed on the upper surface of the first LED stack 1230 (see Figure 43H), a portion of the second-p transparent electrode 1350 (see further Figure 43H), a portion of the upper surface of the second LED stack 1330 (see Figure 43J), a portion of the third-p transparent electrode 1450 (see Figure 43H), and the upper surface of the third LED stack 1430 are exposed to the outside.

[0270] The third LED stack 1430 may have a roughened surface 1430a on its top surface. The roughened surface 1430a may be formed over the entire top surface of the third LED stack 1430, or may be formed in some regions thereof, as shown in FIG.

[0271] The lower insulating layer 1610 may cover the side surfaces of each pixel. The lower insulating layer 1610 may be formed of an optically transparent material such as SiO2. In this case, the lower insulating layer 1610 may cover the entire upper surface of the third LED stack 1430. Alternatively, the lower insulating layer 1610 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first to third LED stacks 1230, 1330, and 1430. In this case, the lower insulating layer 1610 may partially expose the upper surface of the third LED stack 1430.

[0272] The lower insulating layer 1610 may include an opening 1610a exposing the top surface of the third LED stack 1430, an opening 1610b exposing the top surface of the second LED stack 1330, an opening 1610c (see Figure 43H) exposing the ohmic electrode 1290 of the first LED stack 1230, an opening 1610d exposing the third-p transparent electrode 1450, an opening 1610e exposing the second-p transparent electrode 1350, and an opening 1610f exposing the first-p reflective electrode 1250.

[0273] The interconnection lines 1710 and 1750 are formed on the support substrate 1510 near the first to third LED stacks 1230, 1330, and 1430, and are disposed on the lower insulating layer 1610 so as to be insulated from the first-p reflective electrode 1250. The connection portion 1770a connects the third-p transparent electrode 1450 to the reflective electrode 1250, and the connection portion 1770b connects the second-p transparent electrode 1350 to the reflective electrode 1250, so that the anodes of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 are commonly connected to the reflective electrode 1250.

[0274] A connecting portion 1710 a connects the top surface of the third LED stack 1430 to the interconnection line 1710 , and a connecting portion 1750 a connects the ohmic electrode 1290 of the first LED stack 1230 to the interconnection line 1750 .

[0275] An upper insulating layer 1810 is disposed on the interconnection lines 1710 and 1730 and the lower insulating layer 1610 so as to cover the upper surface of the third LED stack 1430. The upper insulating layer 1810 may have an opening 1810a that partially exposes the upper surface of the second LED stack 1330.

[0276] The interconnection line 1730 is disposed on the upper insulating layer 1810, and the connecting portion 1730a can connect the upper surface of the second LED stack 1330 to the interconnection line 1730. The connecting portion 1730a can pass through an upper portion of the interconnection line 1750 and is insulated from the interconnection line 1750 by the upper insulating layer 1810.

[0277] Although the electrodes of each pixel in the illustrated exemplary embodiment are described as being connected to data lines and scan lines, various embodiments are possible. At the same time, although the interconnection lines 1710 and 1750 are described as being formed on the lower insulating layer 1610 and the interconnection line 1730 is described as being formed on the upper insulating layer 1810, the concept of the present invention is not limited thereto. For example, each of the interconnection lines 1710, 1730, and 1750 may be formed on the lower insulating layer 1610 and covered by the upper insulating layer 1810, which may have an opening for exposing the interconnection line 1730. In this structure, the connecting portion 1730a can connect the upper surface of the second LED stack 1330 to the interconnection line 1730 through the opening in the upper insulating layer 1810.

[0278] Alternatively, the interconnection lines 1710, 1730 and 1750 may be formed inside the support substrate 1510, and connection portions 1710a, 1730a and 1750a on the lower insulating layer 1610 may connect the ohmic electrodes 1290, the upper surface of the second LED stack 1330 and the upper surface of the third LED stack 1430 to the interconnection lines 1710, 1730 and 1750.

[0279] 43A-43K are schematic plan views illustrating a method of manufacturing a display device including the pixel of FIG. 40 according to an example embodiment.

[0280] First, the light-emitting diode stack 1000 described with reference to FIG. 36 is prepared.

[0281] 43A, a roughened surface 1430a is formed on the top surface of the third LED stack 1430. The roughened surface 1430a may correspond to each pixel area on the top surface of the third LED stack 1430. The roughened surface 1430a may be formed by chemical etching, such as photo-enhanced chemical etching (PEC).

[0282] The roughened surface 1430a may be formed partially within each pixel area in consideration of the area of ​​the third LED stack 1430 that will be etched in a subsequent process, but is not limited to this. Alternatively, the roughened surface 1430a may be formed on the entire upper surface of the third LED stack 1430.

[0283] 43B, in each pixel, the peripheral region of the third LED stack 1430 is removed by etching to expose the third-p transparent electrode 1450. As shown in FIG. 43B, the third LED stack 1430 may remain having a rectangular or square shape. The third LED stack 1430 may have multiple recesses along its periphery.

[0284] 43C , the top surface of the second LED stack 1330 is exposed by removing the third-p transparent electrode 1450 that was exposed in an area other than one of the recesses of the third LED stack 1430. Thus, the top surface of the second LED stack 1330 is exposed around the third LED stack 1430 and in other recesses except for the recess in which the third-p transparent electrode 1450 partially remains.

[0285] Referring to FIG. 43D, the second-p transparent electrode 1350 is exposed by removing the second LED stack 1330 exposed in an area other than the other recess of the third LED stack 1430.

[0286] 43E , the ohmic electrode 1290 is exposed along with the top surface of the first LED stack 1230 by removing the second-p transparent electrode 1350 exposed in an area other than the other one of the depressions of the third LED stack 1430. In this case, the ohmic electrode 1290 may be exposed in one of the depressions. Thus, the top surface of the first LED stack 1230 is exposed around the third LED stack 1430, and the top surface of the ohmic electrode 1290 is exposed in one or more of the depressions formed in the third LED stack 1430.

[0287] 43F, the reflective electrode 1250 is exposed by removing the exposed portion of the first LED stack 1230 except for the exposed ohmic electrode 1290 in one recess. The reflective electrode 1250 is exposed around the third LED stack 1430.

[0288] Referring to FIG. 43G, linear interconnection lines are formed by patterning the reflective electrode 1250. Here, the support substrate 1510 may be exposed. The reflective electrode 1250 may connect pixels arranged in one row among the pixels arranged in a matrix (see FIG. 39). Referring to FIG. 43H, a lower insulating layer 1610 (see FIGS. 41 and 42) is formed to cover the pixels. The lower insulating layer 1610 covers the side surfaces of the reflective electrode 1250 and the first to third LED stacks 1230, 1330, and 1430. The lower insulating layer 1610 may also at least partially cover the top surface of the third LED stack 1430. If the lower insulating layer 1610 is a transparent layer such as a SiO2 layer, the lower insulating layer 1610 may cover the entire top surface of the third LED stack 1430. Alternatively, when the lower insulating layer 1610 includes a distributed Bragg reflector, the lower insulating layer 1610 may at least partially expose the top surface of the third LED stack 1430 so that light can be emitted to the outside.

[0289] The lower insulating layer 1610 may include an opening 1610a exposing the third LED stack 1430, an opening 1610b exposing the second LED stack 1330, an opening 1610c exposing the ohmic electrode 1290, an opening 1610d exposing the third-p transparent electrode 1450, an opening 1610e exposing the second-p transparent electrode 1350, and an opening 1610f exposing the reflective electrode 1250. One or more openings 1610f are formed to expose the reflective electrode 1250.

[0290] 43I, interconnection lines 1710 and 1750 and connecting portions 1710a, 1750a, 1770a, and 1770b are formed. These are formed by a lift-off process or the like. The interconnection lines 1710 and 1750 are insulated from the reflective electrode 1250 by a lower insulating layer 1610. The connecting portion 1710a electrically connects the third LED stack 1430 to the interconnection line 1710, and the connecting portion 1750a electrically connects the ohmic electrode 1290 to the interconnection line 1750 so that the first LED stack 1230 is electrically connected to the interconnection line 1750. The connecting portion 1770a electrically connects the third-p transparent electrode 1450 to the first-p reflective electrode 1250, and the connecting portion 1770b electrically connects the second-p transparent electrode 1350 to the first-p reflective electrode 1250.

[0291] Referring to FIG. 43J, the upper insulating layer 1810 (see FIGS. 41 and 42) covers the interconnection lines 1710 and 1750 and the connecting portions 1710a, 1750a, 1770a, and 1770b. The upper insulating layer 1810 may further cover the entire upper surface of the third LED stack 1430. The upper insulating layer 1810 has an opening 1810a that exposes the upper surface of the second LED stack 1330. The upper insulating layer 1810 may be formed of, for example, silicon oxide or silicon nitride and may include a distributed Bragg reflector. When the upper insulating layer 1810 includes a distributed Bragg reflector, the upper insulating layer 1810 may expose at least a portion of the upper surface of the third LED stack 1430 so that light can be emitted to the outside.

[0292] 43K, the interconnection line 1730 and the connecting portion 1730a are formed. The interconnection line 1750 and the connecting portion 1750a are formed by a lift-off process or the like. The interconnection line 1730 is disposed on the upper insulating layer 1810 and is insulated from the reflective electrode 1250 and the interconnection lines 1710 and 1750. The connecting portion 1730a electrically connects the second LED stack 1330 to the interconnection line 1730. The connecting portion 1730a can penetrate the upper portion of the interconnection line 1750 and is insulated from the interconnection line 1750 by the upper insulating layer 1810.

[0293] In this way, a pixel region is formed as shown in Fig. 40. Also, as shown in Fig. 39, a plurality of pixels are formed on a support substrate 1510 and connected to each other by a reflective electrode 1250 and interconnection lines 1710, 1730 and 1750 so as to operate in a passive matrix manner.

[0294] Although the above display devices have been described as being configured to operate in a passive matrix manner, the inventive concept is not limited thereto. More specifically, display devices according to some exemplary embodiments can be fabricated in various ways to operate in a passive matrix manner using the light emitting diode stack shown in FIG.

[0295] For example, although interconnection line 1730 is shown as being formed on upper insulating layer 1810, interconnection line 1730 is formed on lower insulating layer 1610 along with interconnection lines 1710 and 1750, with connecting portion 1730a formed on upper insulating layer 1810 to connect second LED stack 1330 to interconnection line 1730. Alternatively, interconnection lines 1710, 1730, and 1750 may be disposed within support substrate 1510.

[0296] 44 is a schematic circuit diagram of a display device according to another exemplary embodiment. The display device according to the illustrated exemplary embodiment can be driven by an active matrix method.

[0297] Referring to FIG. 44, a driving circuit according to an exemplary embodiment includes two or more transistors Tr1 and Tr2 and a capacitor. When a power supply is connected to the select lines Vrow1 to Vrow3 and a voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. The corresponding capacitor is charged according to the value of the data lines Vdata1 to Vdata3. Since the turn-on state of the transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor is maintained and applied to the light-emitting diodes LED1 to LED3 even when the power supplied to the select line Vrow1 is cut off. The current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the value of the data lines Vdata1 to Vdata3. The current is continuously supplied via a current supply source Vdd so that light can be continuously emitted.

[0298] The transistors Tr1 and Tr2 and the capacitor are formed inside a support substrate 1510. For example, thin film transistors formed on a silicon substrate can be used for active matrix driving.

[0299] The light emitting diodes LED1 to LED3 may correspond to the first to third LED stacks 1230, 1330, and 1430, respectively, stacked in one pixel. The anodes of the first to third LED stacks are connected to a transistor Tr2, and the cathodes thereof are connected to ground.

[0300] 44 shows a circuit for active matrix driving according to an exemplary embodiment, various other types of circuits can be used. At the same time, although the anodes of the light emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2 and the cathodes thereof are described as being connected to ground, the concept of the present invention is not limited thereto, and the anodes of the light emitting diodes may be connected to a current supply source Vdd and the cathodes thereof may be connected to different transistors.

[0301] 45 is a schematic plan view of a pixel of a display device according to another exemplary embodiment. The pixel described herein may be one of a plurality of pixels arranged on a support substrate 1511.

[0302] Referring to FIG. 45, the pixel according to the illustrated exemplary embodiment is substantially similar to the pixel described with reference to FIGS. 39 to 42, except that the support substrate 1511 is a thin film transistor panel including transistors and capacitors, and the reflective electrode is disposed in a lower region of the first LED stack.

[0303] The cathode of the third LED stack is connected to the support substrate 1511 via connecting portion 1711a. For example, as shown in Fig. 45, the cathode of the third LED stack is connected to ground by an electrical connection to the support substrate 1511. The cathodes of the second LED stack and the first LED stack are also connected to ground by electrical connections to the support substrate 1511 via connecting portions 1731a and 1751a.

[0304] The reflective electrode is connected to the transistor Tr2 (see FIG. 44) inside the support substrate 1511. The third-p transparent electrode and the second-p transparent electrode are further connected to the transistor Tr2 (see FIG. 44) inside the support substrate 1511 via connection portions 1771a and 1731b.

[0305] In this manner, the first to third LED stacks are connected to each other, thereby forming a circuit for active matrix driving, as shown in FIG.

[0306] Although FIG. 45 shows the electrical connection of pixels for active matrix driving according to an exemplary embodiment, the concept of the present invention is not limited thereto, and the circuit for the display device can be modified into various circuits for active matrix driving in various ways.

[0307] 36 are described as forming ohmic contacts with the corresponding p-type semiconductor layers of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430, respectively. The ohmic electrode 1290 forms ohmic contact with the n-type semiconductor layer of the first LED stack 1230, but the n-type semiconductor layers of the second LED stack 1330 and the third LED stack 1430 do not have separate ohmic contact layers. When the pixel size is small (200 μm or less), current spreading is less difficult even without separate ohmic contact layers on the n-type semiconductor layers. However, according to some embodiments, a transparent electrode layer is disposed on each n-type semiconductor layer of the LED stack to ensure current spreading.

[0308] Furthermore, although the first to third LED stacks 1230, 1330, and 1430 are bonded to each other via bonding layers 1530, 1550, and 1570, the concept of the present invention is not limited thereto, and the first to third LED stacks 1230, 1330, and 1430 may be connected to each other in various orders and using various structures.

[0309] According to the exemplary embodiment, the light emitting diode stack 1000 for a display can be used to form multiple pixels at the wafer level, thereby eliminating the need for individual packaging of light emitting diodes. Additionally, the light emitting diode stack according to the exemplary embodiment has a structure in which the first to third LED stacks 1230, 1330, and 1430 are vertically stacked to secure an area for a subpixel within a limited pixel area. Furthermore, the light emitting diode stack according to the exemplary embodiment allows light generated from the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 to be emitted to the outside therethrough, thereby reducing light loss.

[0310] FIG. 46 is a schematic cross-sectional view of a light emitting diode stack for a display according to an example embodiment.

[0311] 46, the light emitting diode stack 2000 includes a support substrate 2510, a first LED stack 2230, a second LED stack 2330, a third LED stack 2430, a reflective electrode 2250, an ohmic electrode 2290, a second-p transparent electrode 2350, a third-p transparent electrode 2450, an insulating layer 2270, a first bonding layer 2530, a second bonding layer 2550, and a third bonding layer 2570. The first LED stack 2230 may also include an ohmic contact portion 2230a for ohmic contact.

[0312] Generally, light emitted from the second LED stack may cause light to be emitted from the first LED stack, and light emitted from the third LED stack may cause light to be emitted from the second LED stack. Thus, color filters may be interposed between the second LED stack and the first LED stack and between the third LED stack and the second LED stack.

[0313] However, although the color filter can prevent light interference, forming the color filter increases the complexity of manufacturing. The display device according to the exemplary embodiment does not arrange a color filter between the LED stacks, and can suppress the generation of secondary light between the LED stacks.

[0314] Thus, in some exemplary embodiments, optical interference between LED stacks can be reduced by controlling the bandgaps of each of the LED stacks, as described in more detail below.

[0315] Support substrate 2510 supports semiconductor stacks 2230, 2330, and 2430. Support substrate 2510 may include circuitry on or within its surface, although the inventive concept is not limited in this respect. Support substrate 2510 may include, for example, a Si substrate, a Ge substrate, a sapphire substrate, a patterned sapphire substrate, a glass substrate, or a patterned glass substrate.

[0316] Each of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multiple quantum well structure.

[0317] The light L1 emitted from the first LED stack 2230 has a longer wavelength than the light L2 emitted from the second LED stack 2330, and the light L2 emitted from the second LED stack 2330 has a longer wavelength than the light L3 emitted from the third LED stack 2430.

[0318] The first LED stack 2230 may be an inorganic light emitting diode configured to emit red light, the second LED stack 2330 may be an inorganic light emitting diode configured to emit green light, and the third LED stack 2430 may be an inorganic light emitting diode configured to emit blue light. The first LED stack 2230 may include a GaInP-based well layer, and each of the second LED stack 2330 and the third LED stack 2430 may include a GaInN-based well layer.

[0319] 46 is shown as including three LED stacks 2230, 2330, and 2430, the inventive concept is not limited to a particular number of stacked LED stacks. For example, an additional LED stack for emitting yellow light may be added between the first LED stack 2230 and the second LED stack 2330.

[0320] The two surfaces of each of the first through third LED stacks 2230, 2330, and 2430 are n-type and p-type semiconductor layers, respectively. In FIG. 46, each of the first through third LED stacks 2230, 2330, and 2430 is illustrated as having an n-type upper surface and a p-type lower surface. Because the third LED stack 2430 has an n-type upper surface, a roughened surface is formed on the upper surface of the third LED stack 2430, such as by chemical etching. However, the concept of the present invention is not limited in this respect, and the semiconductor types of the upper and lower surfaces of each LED stack may be alternatively formed.

[0321] The first LED stack 2230 is disposed near the support substrate 2510, the second LED stack 2330 is disposed on the first LED stack 2230, and the third LED stack 2430 is disposed on the second LED stack. Because the first LED stack 2230 emits light having a longer wavelength than the second and third LED stacks 2330 and 2430, light L1 generated from the first LED stack 2230 is emitted to the outside via the second and third LED stacks 2330 and 2430. Because the second LED stack 2330 emits light having a longer wavelength than the third LED stack 2430, light L2 generated from the second LED stack 2330 is emitted to the outside via the third LED stack 2430. Light L3 generated in the third LED stack 2430 is emitted directly from the third LED stack 2430 to the outside.

[0322] In an example embodiment, the n-type semiconductor layer of the first LED stack 2230 may have a bandgap wider than the bandgap of the active layer of the first LED stack 2230 and narrower than the bandgap of the active layer of the second LED stack 2330. Therefore, a portion of the light generated from the second LED stack 2330 can be absorbed by the n-type semiconductor layer of the first LED stack 2230 before reaching the active layer of the first LED stack 2230. In this way, the luminous intensity of the light generated in the active layer of the first LED stack 2230 can be reduced by the light generated from the second LED stack 2330.

[0323] At the same time, the n-type semiconductor layer of the second LED stack 2330 has a bandgap wider than the bandgap of the active layers of the first LED stack 2230 and the second LED stack 2330, and narrower than the bandgap of the active layer of the third LED stack 2430. Therefore, a portion of the light generated from the third LED stack 2430 can be absorbed by the n-type semiconductor layer of the second LED stack 2330 before reaching the active layer of the second LED stack 2330. In this way, the luminous intensity of the light generated in the second LED stack 2330 or the first LED stack 2230 can be reduced by the light generated from the third LED stack 2430.

[0324] The p-type and n-type semiconductor layers of the third LED stack 2430 have a wider bandgap than the active layers of the first LED stack 2230 and the second LED stack 2330, thereby allowing light generated from the first and second LED stacks 2230 and 2330 to be transmitted therethrough.

[0325] According to an example embodiment, adjusting the band gap of the n-type or p-type semiconductor layer of the first and second LED stacks 2230 and 2330 can reduce optical interference between the LED stacks 2230, 2330, and 2430, thereby eliminating the need for other components such as color filters. For example, the luminous intensity of light generated from the second LED stack 2330 and emitted to the outside may be approximately 10 times or more the luminous intensity of light generated from the first LED stack 2230 by the light generated from the second LED stack 2330. Similarly, the luminous intensity of light generated from the third LED stack 2430 and emitted to the outside may be approximately 10 times or more the luminous intensity of light generated from the second LED stack 2330 stimulated by the light generated from the third LED stack 2430. In this case, the luminous intensity of light generated from the third LED stack 2430 and emitted to the outside may be approximately 10 times or more the luminous intensity of light generated from the first LED stack 2230 stimulated by the light generated from the third LED stack 2430. It is therefore possible to realize a display device free from color contamination induced by light interference.

[0326] The reflective electrode 2250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 2230 and reflects light generated from the first LED stack 2230. For example, the reflective electrode 2250 may include an ohmic contact layer 2250a and a reflective layer 2250b.

[0327] The ohmic contact layer 2250a partially contacts the p-type semiconductor layer of the first LED stack 2230. To prevent light absorption by the ohmic contact layer 2250a, the area where the ohmic contact layer 2250a contacts the p-type semiconductor layer may not exceed approximately 50% of the entire area of ​​the p-type semiconductor layer. The reflective layer 2250b covers the ohmic contact layer 2250a and the insulating layer 2270. As shown in FIG. 46, the reflective layer 2250b can cover substantially the entire ohmic contact layer 2250a, but is not limited to this. Alternatively, the reflective layer 2250b can cover only a portion of the ohmic contact layer 2250a.

[0328] Because the reflective layer 2250b covers the insulating layer 2270, an omnidirectional reflector is formed by the stacked structure of the first LED stack 2230 having a relatively high refractive index, the insulating layer 2270 having a relatively low refractive index, and the reflective layer 2250b. The reflective layer 2250b can cover about 50% or more of the area of ​​the first LED stack 2230 or most of the first LED stack 2230, thereby improving luminous efficiency.

[0329] The ohmic contact layer 2250a and the reflective layer 2250b are formed of a metal layer that may include gold (Au). The reflective layer 2250b may include a metal that has a relatively high reflectivity for light generated from the first LED stack 2230, for example, red light. On the other hand, the reflective layer 2250b may include a metal that has a relatively low reflectivity for light generated from the second LED stack 2330 and the third LED stack 2430, for example, green light or blue light, and may reduce interference of light generated from the second and third LED stacks 2330 and 2430 and traveling toward the support substrate 2510.

[0330] The insulating layer 2270 is interposed between the support substrate 2510 and the first LED stack 2230 and has an opening exposing the first LED stack 2230. The ohmic contact layer 2250a is connected to the first LED stack 2230 within the opening of the insulating layer 2270.

[0331] An ohmic electrode 2290 is disposed on the upper surface of the first LED stack 2230. To reduce the ohmic contact resistance of the ohmic electrode 2290, an ohmic contact portion 2230a may protrude from the upper surface of the first LED stack 2230. The ohmic electrode 2290 is disposed on the ohmic contact portion 2230a.

[0332] The second-p transparent electrode 2350 forms an ohmic contact with the p-type semiconductor layer of the second LED stack 2330. The second-p transparent electrode 2350 is formed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0333] The third-p transparent electrode 2450 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 2430. The third-p transparent electrode 2450 is formed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0334] The reflective electrode 2250, the second-p transparent electrode 2350 and the third-p transparent electrode 2450 can assist in current spreading by making ohmic contact with the p-type semiconductor layers of the corresponding LED stacks.

[0335] A first bonding layer 2530 bonds the first LED stack 2230 to the support substrate 2510. As shown in Figure 46, a reflective electrode 2250 may be adjacent to the first bonding layer 2530. The first bonding layer 2530 may be a light-transmitting or opaque layer.

[0336] The second bonding layer 2550 bonds the second LED stack 2330 to the first LED stack 2230. As shown in FIG. 46, the second bonding layer 2550 may be adjacent to the first LED stack 2230 and the second-p transparent electrode 2350. The ohmic electrode 2290 may be covered by the second bonding layer 2550. The second bonding layer 2550 transmits light generated from the first LED stack 2230. The second bonding layer 2550 may be formed of an optically transparent bonding material, such as an optically transparent organic bonding agent or an optically transparent spin-on glass. Examples of optically transparent organic bonding agents include SU8, poly(methyl methacrylate) (PMMA), polyimide, Parylene, benzocyclobutene (BCB), etc. At the same time, the second LED stack 2330 may be bonded to the first LED stack 2230 by plasma bonding or the like.

[0337] The third bonding layer 2570 couples the third LED stack 2430 to the second LED stack 2330. As shown in FIG. 46 , the third bonding layer 2570 may be adjacent to the second LED stack 2330 and the third-p transparent electrode 2450. However, the concept of the present invention is not limited in this respect. For example, a transparent conductive layer may be disposed on the second LED stack 2330. The third bonding layer 2570 transmits light generated from the first LED stack 2230 and the second LED stack 2330 and may be formed of, for example, light-transmitting spin-on glass.

[0338] The second bonding layer 2550 and the third bonding layer 2570 can transmit light generated from the third LED stack 2430 and the light generated from the second LED stack 2330, respectively.

[0339] 47A-47E are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack for a display according to an example embodiment.

[0340] 47A , the first LED stack 2230 is grown on a first substrate 2210. The first substrate 2210 may be, for example, a GaAs substrate. The first LED stack 2230 is formed of an AlGaInP-based semiconductor layer and includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. In some example embodiments, the n-type semiconductor layer may have an energy bandgap capable of absorbing light generated from the second LED stack 2330, and the p-type semiconductor layer may have an energy bandgap capable of absorbing light generated from the second LED stack 2330.

[0341] Insulating layer 2270 is formed on first LED stack 2230 and patterned to form an opening therein. For example, a SiO layer is formed on first LED stack 2230, and photoresist is deposited on the SiO layer, followed by photolithography and development to form a photoresist pattern. The SiO layer is then patterned through the photoresist pattern used as an etching mask, thereby forming insulating layer 2270 with an opening.

[0342] Then, an ohmic contact layer 2250a is formed in the opening of the insulating layer 2270. The ohmic contact layer 2250a is formed by a lift-off process or the like. After the ohmic contact layer 2250a is formed, a reflective layer 2250b is formed to cover the ohmic contact layer 2250a and the insulating layer 2270. The reflective layer 2250b is formed by a lift-off process or the like. The reflective layer 2250b can cover a portion of the ohmic contact layer 2250a or the entire ohmic contact layer 2250a. The ohmic contact layer 2250a and the reflective layer 2250b form a reflective electrode 2250.

[0343] The reflective electrode 2250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 2230 , and is therefore hereinafter referred to as the first-p reflective electrode 2250 .

[0344] 47B , a second LED stack 2330 is grown on a second substrate 2310, and a second-p transparent electrode 2350 is formed on the second LED stack 2330. The second LED stack 2330 is formed of a GaN-based semiconductor layer and may include a GaInN well layer. The second substrate 2310 is a substrate on which a GaN-based semiconductor layer can be grown and is different from the first substrate 2210. The composition ratio of GaInN for the second LED stack 2330 may be determined so that the second LED stack 2330 emits green light. The second-p transparent electrode 2350 forms ohmic contact with the p-type semiconductor layer of the second LED stack 2330. The second LED stack 2330 may include an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. In some demonstrative embodiments, the n-type semiconductor layer of the second LED stack 2330 may have an energy bandgap that can absorb light generated from the third LED stack 2430, and the p-type semiconductor layer of the second LED stack 2330 may have an energy bandgap that can absorb light generated from the third LED stack 2430.

[0345] 47C , a third LED stack 2430 is grown on a third substrate 2410, and a third-p transparent electrode 2450 is formed on the third LED stack 2430. The third LED stack 2430 is formed of a GaN-based semiconductor layer and may include a GaInN well layer. The third substrate 2410 is a substrate on which a GaN-based semiconductor layer can be grown and is different from the first substrate 2210. The composition ratio of GaInN for the third LED stack 2430 may be determined so that the third LED stack 2430 emits blue light. The third-p transparent electrode 2450 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 2430.

[0346] In this manner, the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 are grown on different substrates, and the order of their formation is not limited to any particular order.

[0347] 47D , the first LED stack 2230 is bonded to the support substrate 2510 via a first bonding layer 2530. The first bonding layer 2530 may be pre-formed on the support substrate 2510, and the reflective electrode 2250 may be bonded to the first bonding layer 2530 facing the support substrate 2510. The first substrate 2210 is removed from the first LED stack 2230 by chemical etching or the like. Thus, the top surface of the n-type semiconductor layer of the first LED stack 2230 is exposed.

[0348] Thereafter, an ohmic electrode 2290 is formed in the exposed area of ​​the first LED stack 2230. The ohmic electrode 2290 is subjected to a heat treatment to reduce the ohmic contact resistance of the ohmic electrode 2290. The ohmic electrode 2290 is formed in each pixel area to correspond to the pixel area.

[0349] 47E , the second LED stack 2330 is coupled to the first LED stack 2230, on which the ohmic electrode 2290 is formed, via a second bonding layer 2550. The second-p transparent electrode 2350 is bonded to the second bonding layer 2550 facing the first LED stack 2230. The second bonding layer 2550 may be pre-formed on the first LED stack 2230 such that the second-p transparent electrode 2350 can be bonded to the second bonding layer 2550 facing the second bonding layer 2550. The second substrate 2310 is separated from the second LED stack 2330 by a laser lift-off or chemical lift-off process.

[0350] 46 and 47C , the third LED stack 2430 is coupled to the second LED stack 2330 via the third bonding layer 2570. The third-p transparent electrode 2450 is bonded to the third bonding layer 2570 facing the second LED stack 2330. The third bonding layer 2570 may be pre-formed on the second LED stack 2330 so that the third-p transparent electrode 2450 can be bonded to the third bonding layer 2570 facing the third bonding layer 2570. The third substrate 2410 is separated from the third LED stack 2430 by a laser lift-off or chemical lift-off process. In this manner, a light-emitting diode stack for a display is formed, as shown in FIG. 46 , with the n-type semiconductor layer of the third LED stack 2430 exposed to the outside.

[0351] The display device is formed by patterning the stack of first to third LED stacks 2230, 2330, and 2430 disposed on the support substrate 2510 in pixel units, and then connecting the first to third LED stacks 2230, 2330, and 2430 to each other by interconnections. However, the concept of the present invention is not limited thereto. For example, the display device can be fabricated by dividing the stack of first to third LED stacks 2230, 2330, and 2430 into individual units and transferring the first to third LED stacks 2230, 2330, and 2430 to another support substrate, such as a printed circuit board.

[0352] Fig. 48 is a schematic circuit diagram of a display device according to an exemplary embodiment. Fig. 49 is a schematic plan view of a display device according to an exemplary embodiment.

[0353] Referring to Figures 48 and 49, the display device according to the exemplary embodiment can be realized to be driven in a passive matrix manner.

[0354] 46 has a structure including vertically stacked first to third LED stacks 2230, 2330, and 2430. Since one pixel includes three light emitting diodes R, G, and B, the first light emitting diode R can correspond to the first LED stack 2230, the second light emitting diode G can correspond to the second LED stack 2330, and the third light emitting diode B can correspond to the third LED stack 2430.

[0355] 48 and 49, one pixel includes first to third light emitting diodes R, G, and B, each of which may correspond to a subpixel. The anodes of the first to third light emitting diodes R, G, and B are connected to a common line, such as a data line, and the cathodes are connected to different lines, such as scan lines. For example, in a first pixel, the anodes of the first to third light emitting diodes R, G, and B are commonly connected to the data line Vdata1, and the cathodes are connected to scan lines Vscan1-1, Vscan1-2, and Vscan1-3, respectively. In this way, the light emitting diodes R, G, and B in each pixel can be driven independently.

[0356] At the same time, each of the light emitting diodes R, G and B can be driven by pulse width modulation or by varying the magnitude of the current to control the brightness of each sub-pixel.

[0357] Referring to Figure 49, a plurality of pixels are formed by patterning the stack of Figure 46, and each of the pixels is connected to a reflective electrode 2250 and interconnection lines 2710, 2730, and 2750. As shown in Figure 48, the reflective electrode 2250 can be used as a data line Vdata, and the interconnection lines 2710, 2730, and 2750 can be formed as scan lines.

[0358] The pixels are arranged in a matrix, with the anodes of the light-emitting diodes R, G, and B of each pixel commonly connected to a reflective electrode 2250, and the cathodes connected to interconnection lines 2710, 2730, and 2750 that are separated from each other. Here, the interconnection lines 2710, 2730, and 2750 can be used as scan lines Vscan.

[0359] Fig. 50 is an enlarged plan view of one pixel of the display device of Fig. 49. Fig. 51 is a schematic cross-sectional view taken along line AA in Fig. 50, and Fig. 52 is a schematic cross-sectional view taken along line BB in Fig. 50.

[0360] Referring to Figures 49 to 52, in each pixel, a portion of the reflective electrode 2250, an ohmic electrode 2290 formed on the upper surface of the first LED stack 2230 (see Figure 53H), a portion of the second-p transparent electrode 2350 (see Figure 53H), a portion of the upper surface of the second LED stack 2330 (see Figure 53J), a portion of the third-p transparent electrode 2450 (see Figure 53H), and the upper surface of the third LED stack 2430 are exposed to the outside.

[0361] The third LED stack 2430 may have a roughened surface 2430a on its top surface. The roughened surface 2430a may be formed over the entire top surface of the third LED stack 2430, or may be formed in some regions thereof.

[0362] The lower insulating layer 2610 may cover the side surfaces of each pixel. The lower insulating layer 2610 may be formed of an optically transparent material such as SiO 2. In this case, the lower insulating layer 2610 may cover substantially the entire upper surface of the third LED stack 2430. Alternatively, the lower insulating layer 2610 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first to third LED stacks 2230, 2330, and 2430. In this case, the lower insulating layer 2610 may partially expose the upper surface of the third LED stack 2430. Alternatively, the lower insulating layer 2610 may be a light-absorbing black-based insulation layer. Furthermore, an electrically floating metal reflective layer may be further formed on the lower insulating layer 2610 to reflect light emitted through the side surfaces of the first to third LED stacks 2230, 2330, and 2430.

[0363] The lower insulating layer 2610 may include an opening 2610a exposing the top surface of the third LED stack 2430, an opening 2610b exposing the top surface of the second LED stack 2330, an opening 2610c (see Figure 53H) exposing the ohmic electrode 2290 of the first LED stack 2230, an opening 2610d exposing the third-p transparent electrode 2450, an opening 2610e exposing the second-p transparent electrode 2350, and an opening 2610f exposing the first-p reflective electrode 2250.

[0364] The interconnection lines 2710 and 2750 are formed on the support substrate 2510 near the first to third LED stacks 2230, 2330, and 2430, and are disposed on the lower insulating layer 2610 so as to be insulated from the first-p reflective electrode 2250. The connection portion 2770a connects the third-p transparent electrode 2450 to the reflective electrode 2250, and the connection portion 2770b connects the second-p transparent electrode 2350 to the reflective electrode 2250, so that the anodes of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 are commonly connected to the reflective electrode 2250.

[0365] Connection portion 2710 a connects the top surface of the third LED stack 2430 to the interconnection line 2710 , and connection portion 2750 a connects the ohmic electrode 2290 on the first LED stack 2230 to the interconnection line 2750 .

[0366] An upper insulating layer 2810 may be disposed on the interconnection lines 2710 and 2730 and the lower insulating layer 2610 and cover the top surface of the third LED stack 2430. The upper insulating layer 2810 may have an opening 2810a that partially exposes the top surface of the second LED stack 2330.

[0367] The interconnection line 2730 is disposed on the upper insulating layer 2810, and the connecting portion 2730a can connect the upper surface of the second LED stack 2330 to the interconnection line 2730. The connecting portion 2730a can pass through an upper portion of the interconnection line 2750 and is insulated from the interconnection line 2750 by the upper insulating layer 2810.

[0368] Although the electrodes of each pixel are described as being connected to data lines and scan lines, the concept of the present invention is not limited in this manner. Also, although interconnection lines 2710 and 2750 are described as being formed on lower insulating layer 2610 and interconnection line 2730 is described as being formed on upper insulating layer 2810, the concept of the present invention is not limited in this manner. For example, all interconnection lines 2710, 2730, and 2750 may be formed on lower insulating layer 2610 and covered by upper insulating layer 2810, which may have an opening exposing interconnection line 2730. In this manner, connecting portion 2730a can connect the upper surface of second LED stack 2330 to interconnection line 2730 through the opening in upper insulating layer 2810.

[0369] Alternatively, interconnection lines 2710, 2730 and 2750 may be formed inside support substrate 2510, and connection portions 2710a, 2730a and 2750a on lower insulating layer 2610 can connect ohmic electrode 2290, the upper surface of first LED stack 2230 and the upper surface of third LED stack 2430 to interconnection lines 2710, 2730 and 2750.

[0370] According to an example embodiment, light L1 generated from the first LED stack 2230 is emitted to the outside via the second and third LED stacks 2330 and 2430, and light L2 generated from the second LED stack 2330 is emitted to the outside via the third LED stack 2430. Also, a portion of light L3 generated from the third LED stack 2430 may enter the second LED stack 2330, and a portion of light L2 generated from the second LED stack 2330 may enter the first LED stack 2230. Furthermore, secondary light may be generated from the second LED stack 2330 by the light L3, and secondary light may be generated from the first LED stack 2230 by the light L2. However, such secondary light may have low luminous intensity.

[0371] 53A-53K are schematic plan views illustrating a method of manufacturing a display device according to an example embodiment. The following description is given with reference to the pixel of FIG.

[0372] First, a light-emitting diode stack 2000 shown in FIG. 46 is prepared.

[0373] 53A, a roughened surface 2430a is formed on the upper surface of the third LED stack 2430. The roughened surface 2430a is formed on the upper surface of the third LED stack 2430 to correspond to each pixel area. The roughened surface 2430a is formed by chemical etching, such as photo-enhanced chemical etching (PEC).

[0374] The roughened surface 2430a may be formed partially in each pixel area in consideration of the area of ​​the third LED stack 2430 that will be etched in a subsequent process, but is not limited to this. Alternatively, the roughened surface 2430a may be formed on the entire upper surface of the third LED stack 2430.

[0375] 53B, the peripheral region of the third LED stack 2430 in each pixel is removed by etching to expose the third-p transparent electrode 2450. As shown in FIG. 53B, the third LED stack 2430 may remain having a rectangular or square shape. The third LED stack 2430 may have a plurality of recesses formed along its periphery.

[0376] 53C , the top surface of the second LED stack 2330 is exposed by removing the third-p transparent electrode 2450 that is exposed in areas other than one of the recesses. Thus, the top surface of the second LED stack 2330 is exposed around the third LED stack 2430 and in other recesses other than the recess where the third-p transparent electrode 2450 partially remains.

[0377] Referring to FIG. 53D, the second-p transparent electrode 2350 is exposed by removing the second LED stack 2330 exposed in an area other than one recess.

[0378] 53E , the ohmic electrode 2290 is exposed along with the top surface of the first LED stack 2230 by removing the second-p transparent electrode 2350 exposed in an area other than one of the recesses. Here, the ohmic electrode 2290 may be exposed in one of the recesses. Thus, the top surface of the first LED stack 2230 is exposed around the third LED stack 2430, and the top surface of the ohmic electrode 2290 is exposed in one or more of the recesses formed in the third LED stack 2430.

[0379] 53F, the reflective electrode 2250 is exposed by removing the exposed portion of the first LED stack 2230 in an area other than one of the recesses. In this manner, the reflective electrode 2250 is exposed around the third LED stack 2430.

[0380] Referring to Fig. 53G, a linear interconnection line is formed by patterning the reflective electrode 2250. Here, the support substrate 2510 may be exposed. The reflective electrode 2250 can connect pixels arranged in one row among the pixels arranged in a matrix (see Fig. 49).

[0381] Referring to FIG. 53H, a lower insulating layer 2610 (see FIGS. 51 and 52) is formed to cover the pixel. The lower insulating layer 2610 covers the reflective electrode 2250 and the side surfaces of the first to third LED stacks 2230, 2330, and 2430. In addition, the lower insulating layer 2610 may partially cover the top surface of the third LED stack 2430. If the lower insulating layer 2610 is a transparent layer such as a SiO layer, the lower insulating layer 2610 may cover substantially the entire top surface of the third LED stack 2430. Alternatively, the lower insulating layer 2610 may include a distributed Bragg reflector. In this case, the lower insulating layer 2610 partially exposes the top surface of the third LED stack 2430, allowing light to radiate to the outside.

[0382] The lower insulating layer 2610 may include an opening 2610a exposing the third LED stack 2430, an opening 2610b exposing the second LED stack 2330, an opening 2610c exposing the ohmic electrode 2290, an opening 2610d exposing the third-p transparent electrode 2450, an opening 2610e exposing the second-p transparent electrode 2350, and an opening 2610f exposing the reflective electrode 2250. The opening 2610f exposing the reflective electrode 2250 may be formed in one or more portions.

[0383] 53I, interconnection lines 2710 and 2750 and connecting portions 2710a, 2750a, 2770a, and 2770b are formed by a lift-off process or the like. The interconnection lines 2710 and 2750 are insulated from the reflective electrode 2250 by a lower insulating layer 2610. The connecting portion 2710a electrically connects the third LED stack 2430 to the interconnection line 2710, and the connecting portion 2750a electrically connects the ohmic electrode 2290 to the interconnection line 2750, thereby electrically connecting the first LED stack 2230 to the interconnection line 2750. The connecting portion 2770a electrically connects the third-p transparent electrode 2450 to the first-p reflective electrode 2250, and the connecting portion 2770b electrically connects the second-p transparent electrode 2350 to the first-p reflective electrode 2250.

[0384] Referring to FIG. 53J, an upper insulating layer 2810 (see FIGS. 51 and 52) covers the interconnection lines 2710 and 2750 and the connecting portions 2710a, 2750a, 2770a, and 2770b. The upper insulating layer 2810 can further cover substantially the entire upper surface of the third LED stack 2430. The upper insulating layer 2810 has an opening 2810a that exposes the upper surface of the second LED stack 2330. The upper insulating layer 2810 can be formed of, for example, silicon oxide or silicon nitride and can include a distributed Bragg reflector. When the upper insulating layer 2810 includes a distributed Bragg reflector, the upper insulating layer 2810 exposes at least a portion of the upper surface of the third LED stack 2430 to allow light to radiate outward.

[0385] 53K, the interconnection line 2730 and the connecting portion 2730a are formed. The interconnection line 2750 and the connecting portion 2750a are formed by a lift-off process or the like. The interconnection line 2730 is disposed on an upper insulating layer 2810 and is insulated from the reflective electrode 2250 and the interconnection lines 2710 and 2750. The connecting portion 2730a electrically connects the second LED stack 2330 to the interconnection line 2730. The connecting portion 2730a can penetrate the upper portion of the interconnection line 2750 and is insulated from the interconnection line 2750 by the upper insulating layer 2810.

[0386] In this way, the pixel area shown in Fig. 50 is formed. At the same time, as shown in Fig. 49, a plurality of pixels are formed on the support substrate 2510 and connected to each other by the reflective electrode 2250 and the interconnection lines 2710, 2730 and 2750 to operate in a passive matrix manner.

[0387] Although the above description has been made regarding a method for manufacturing a display device that can operate in a passive matrix mode, the concept of the present invention is not limited thereto. More specifically, a display device according to an exemplary embodiment can be manufactured in various ways to operate in a passive matrix mode using the light emitting diode stack shown in FIG.

[0388] For example, although interconnection line 2730 is described as being formed on upper insulating layer 2810, interconnection line 2730 may be formed on lower insulating layer 2610 along with interconnection lines 2710 and 2750, and connecting portion 2730a may be formed on upper insulating layer 2810 to connect second LED stack 2330 to interconnection line 2730. Alternatively, interconnection lines 2710, 2730, and 2750 may be disposed within support substrate 2510.

[0389] Fig. 54 is a schematic circuit diagram of a display device according to another exemplary embodiment. The circuit diagram of Fig. 54 relates to a display device driven by an active matrix method.

[0390] Referring to FIG. 54, a driving circuit according to an exemplary embodiment includes two or more transistors Tr1 and Tr2 and a capacitor. When a power supply is connected to the select lines Vrow1 to Vrow3 and a voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. At the same time, the corresponding capacitor is charged according to the value of the data lines Vdata1 to Vdata3. Because the turn-on state of the transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor is maintained and applied to the light-emitting diodes LED1 to LED3 even if the power supplied to the select line Vrow1 is cut off. At the same time, the current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the value of the data lines Vdata1 to Vdata3. The current is continuously supplied via the current supply source Vdd, so that light can be continuously emitted.

[0391] The transistors Tr1 and Tr2 and the capacitor are formed inside a support substrate 2510. For example, thin film transistors formed on a silicon substrate can be used for active matrix driving.

[0392] Here, the light emitting diodes LED1 to LED3 may correspond to the first to third LED stacks 2230, 2330, and 2430, respectively, stacked in one pixel. The anodes of the first to third LED stacks 2230, 2330, and 2430 are connected to a transistor Tr2, and the cathode thereof is connected to ground.

[0393] 54 shows a circuit for active matrix driving according to an exemplary embodiment, various other types of circuits can be used. In addition, although the anodes of the light emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2 and the cathodes thereof are described as being connected to ground, in some exemplary embodiments, the anodes of the light emitting diodes are connected to a current supply source Vdd and the cathodes thereof are connected to different transistors.

[0394] 55 is a schematic plan view of a display device according to another exemplary embodiment. The following description is given with reference to one pixel of a plurality of pixels arranged on a support substrate 2511.

[0395] Referring to FIG. 55, the pixel according to the exemplary embodiment is substantially similar to the pixel described with reference to FIGS. 49 to 52, except that the support substrate 2511 is a thin film transistor panel including transistors and capacitors, and the reflective electrode 2250 is disposed in a lower region of the first LED stack 2230.

[0396] The cathode of the third LED stack 2430 is connected to the support substrate 2511 via connecting portion 2711a. For example, as shown in Fig. 54, the cathode of the third LED stack 2430 is connected to ground by an electrical connection to the support substrate 2511. The cathodes of the second LED stack 2330 and the first LED stack 2230 are further connected to ground by an electrical connection to the support substrate 2511 via connecting portions 2731a and 2751a.

[0397] The reflective electrode is connected to the transistor Tr2 (see FIG. 54) inside the support substrate 2511. The third-p transparent electrode and the second-p transparent electrode are further connected to the transistor Tr2 (see FIG. 54) inside the support substrate 2511 via connection portions 2711b and 2731b.

[0398] In this manner, the first to third LED stacks are connected to each other, thereby forming a circuit for active matrix driving, as shown in FIG. Although FIG. 55 shows a pixel having electrical connections for active matrix driving according to an exemplary embodiment, the concept of the present invention is not limited thereto, and the circuit for the display device can be modified in various ways to various circuits for active matrix driving.

[0399] 46 are described as forming ohmic contact with the p-type semiconductor layers of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430, respectively, and the ohmic electrode 2290 is described as forming ohmic contact with the n-type semiconductor layer of the first LED stack 2230, and no separate ohmic contact layer is provided for the n-type semiconductor layers of the second LED stack 2330 and the third LED stack 2430. When the pixel has a small size of 200 μm or less, there is little difficulty in current spreading even if a separate ohmic contact layer is not formed in the n-type semiconductor layer. However, in some embodiments, a transparent electrode layer is disposed on each n-type semiconductor layer of the LED stack to ensure current spreading.

[0400] At the same time, although FIG. 46 shows the first to third LED stacks 2230, 2330 and 2430 being bonded to one another via bonding layers, the concept of the present invention is not limited thereto, and the first to third LED stacks 2230, 2330 and 2430 may be connected to one another in a variety of orders and using a variety of configurations.

[0401] According to the exemplary embodiment, the light emitting diode stack 2000 for a display can be used to form multiple pixels at the wafer level, thereby eliminating the need for individual packaging of light emitting diodes. Furthermore, the light emitting diode stack according to the exemplary embodiment has a structure in which the first to third LED stacks 2230, 2330, and 2430 are vertically stacked, thereby ensuring an area for subpixels within a limited pixel area. Furthermore, the light emitting diode stack according to the exemplary embodiment allows light generated from the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 to be emitted to the outside, thereby reducing light loss.

[0402] FIG. 56 is a schematic plan view of a display device according to an exemplary embodiment, and FIG. 57 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

[0403] 56 and 57, the display device includes a circuit board 3510 and a plurality of pixels 3000. Each of the pixels 3000 includes a substrate 3210 and first to third sub-pixels R, G, and B arranged on the substrate 3210.

[0404] The circuit board 3510 can include passive or active circuits. Passive circuits can include, for example, data lines and scan lines. Active circuits can include, for example, transistors and capacitors. The circuit board 3510 can have circuits on its surface or within it. The circuit board 3510 can include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

[0405] The substrate 3210 supports the first to third subpixels R, G, and B. The substrate 3210 is continuous over the plurality of pixels 3000 and electrically connects the subpixels R, G, and B to the circuit substrate 3510. For example, the substrate 3210 may be a GaAs substrate.

[0406] The first subpixel R includes a first LED stack 3230, the second subpixel G includes a second LED stack 3330, and the third subpixel B includes a third LED stack 3430. The first subpixel R is configured to allow the first LED stack 3230 to emit light, the second subpixel G is configured to allow the second LED stack 3330 to emit light, and the third subpixel B is configured to allow the third LED stack 3430 to emit light. The first to third LED stacks 3230, 3330, and 3430 are independently drivable.

[0407] The first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 are stacked vertically one on top of the other. Here, as shown in FIG. 57 , the second LED stack 3330 is disposed within a portion of the first LED stack 3230. For example, the second LED stack 3330 is disposed toward one side on the first LED stack 3230. The third LED stack 3430 is disposed within a portion of the second LED stack 3330. For example, the third LED stack 3430 is disposed toward one side on the second LED stack 3330. Although FIG. 57 shows the third LED stack 3430 disposed toward the right side, the concept of the present invention is not limited thereto. Alternatively, the third LED stack 3430 may be disposed toward the left side of the second LED stack 3330.

[0408] Light R generated from the first LED stack 3230 is emitted through the area not covered by the second LED stack 3330, and light G generated from the second LED stack 3330 is emitted through the area not covered by the third LED stack 3430. More specifically, light generated from the first LED stack 3230 is emitted to the outside without penetrating the second LED stack 3330 and the third LED stack 3430, and light generated from the second LED stack 3330 is emitted to the outside without penetrating the third LED stack 3430.

[0409] The area of ​​the first LED stack 3230 through which light R passes and is emitted, the area of ​​the second LED stack 3330 through which light G passes and is emitted, and the area of ​​the third LED stack 3340 may have different areas from each other, and the luminous intensity of the light emitted from each of the LED stacks 3230, 3330, and 3430 can be adjusted by adjusting their areas.

[0410] However, the concept of the present invention is not limited thereto. Alternatively, light generated from the first LED stack 3230 is emitted to the outside after passing through the second LED stack 3330 or after passing through the second LED stack 3330 and the third LED stack 3430, and light generated from the second LED stack 3330 is emitted to the outside after passing through the third LED stack 3430.

[0411] Each of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may include a first conductivity type (e.g., n-type) semiconductor layer, a second conductivity type (e.g., p-type) semiconductor layer, and an active layer interposed therebetween. The active layer may have a multiple quantum well structure. The first to third LED stacks 3230, 3330, and 3430 may include different active layers to emit light having different wavelengths. For example, the first LED stack 3230 may be an inorganic light emitting diode configured to emit red light, the second LED stack 3330 may be an inorganic light emitting diode configured to emit green light, and the third LED stack 3430 may be an inorganic light emitting diode configured to emit blue light. For this purpose, the first LED stack 3230 may include an AlGaInP-based well layer, the second LED stack 3330 may include an AlGaInP or AlGaInN-based well layer, and the third LED stack 3430 may include an AlGaInN-based well layer. However, the concept of the present invention is not limited thereto. The wavelengths of the light generated from the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may be variable. For example, the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may emit green light, red light, and blue light, respectively, or green light, blue light, and red light, respectively.

[0412] At the same time, a distributed Bragg reflector may be interposed between the substrate 3210 and the first LED stack 3230 to prevent loss of light generated from the first LED stack 3230 due to absorption by the substrate 3210. For example, a distributed Bragg reflector formed by alternately stacking AlAs and AlGaAs semiconductor layers may be interposed therebetween.

[0413] FIG. 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0414] 58, the display device according to the exemplary embodiment can be driven by an active matrix method. Thus, the circuit board can include active circuits.

[0415] For example, the driving circuit may include two or more transistors Tr1 and Tr2 and a capacitor. When a power supply is connected to the select lines Vrow1 to Vrow3 and a voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. The corresponding capacitor is charged according to the value of the data lines Vdata1 to Vdata3. Since the turn-on state of the transistor Tr2 can be maintained by the charged voltage of the capacitor, the voltage of the capacitor is maintained and applied to the light-emitting diodes LED1 to LED3 even when the power supplied to the select line Vrow1 is cut off. The current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the value of the data lines Vdata1 to Vdata3. The current is continuously supplied via the current supply source Vdd, so that light can be continuously emitted.

[0416] The transistors Tr1 and Tr2 and the capacitor are formed inside the support substrate 3510. Here, the light-emitting diodes LED1 to LED3 may correspond to the first to third LED stacks 3230, 3330, and 3430, respectively, stacked within one pixel. The anodes of the first to third LED stacks 3230, 3330, and 3430 are connected to the transistor Tr2, and the cathodes thereof are connected to ground. The cathodes of the first to third LED stacks 3230, 3330, and 3430 are commonly connected to ground, for example.

[0417] 58 shows a circuit for active matrix driving according to an exemplary embodiment, other types of circuits may also be used. Also, although the anodes of the light emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2 and the cathodes thereof are described as being connected to ground, in some exemplary embodiments, the anodes of the light emitting diodes may be commonly connected and the cathodes thereof may be connected to different transistors.

[0418] Although an active circuit for active matrix driving has been described, the concept of the present invention is not limited thereto, and pixels according to exemplary embodiments can be driven in a passive matrix manner. Thus, the circuit board 3510 can include data lines and scan lines arranged thereon, and each subpixel is connected to a data line and a scan line. In an exemplary embodiment, the anodes of the first to third LED stacks 3230, 3330, and 3430 are connected to different data lines, and their cathodes are commonly connected to a scan line. In another exemplary embodiment, the anodes of the first to third LED stacks 3230, 3330, and 3430 are connected to different scan lines, and their cathodes are commonly connected to a data line.

[0419] At the same time, each of the LED stacks 3230, 3330, and 3430 can be driven by pulse-width modulation or by changing the magnitude of the current, thereby controlling the brightness of each subpixel. Furthermore, brightness can be adjusted by adjusting the area of ​​the first through third LED stacks 3230, 3330, and 3430 and the area of ​​the regions of the LED stacks 3230, 3330, and 3430 through which R, G, and B light pass and is emitted. For example, an LED stack emitting light with low visibility, such as the first LED stack 3230, has a larger area than the second LED stack 3330 or the third LED stack 3430, and therefore can emit light with higher luminous intensity under the same current density. At the same time, because the area of ​​the second LED stack 3330 is larger than that of the third LED stack 3430, the second LED stack 3330 can emit light with higher luminous intensity than the third LED stack 3430 under the same current density. In this manner, the light output can be adjusted based on the visibility of the light emitted from the first to third LED stacks 3230, 3330 and 3430 by adjusting the areas of the first LED stack 3230, the second LED stack 3330 and the third LED stack 3430.

[0420] Figures 59A and 59B are plan and bottom views of one pixel of a display device according to an exemplary embodiment, and Figures 60A, 60B, 60C and 60D are schematic cross-sectional views along lines AA, BB, CC and DD in Figure 59A, respectively.

[0421] In the display device, pixels are arranged on a circuit board 3510 (see FIG. 56), and each pixel includes a substrate 3210 and sub-pixels R, G, and B. The substrate 3210 may be continuous over multiple pixels. Below, the configuration of a pixel according to an exemplary embodiment will be described.

[0422] 59A, 59B, 60A, 60B, 60C, and 60D, a pixel includes a substrate 3210, a distributed Bragg reflector 3220, an insulating layer 3250, through-hole vias 3270a, 3270b, and 3270c, a first LED stack 3230, a second LED stack 3330, a third LED stack 3430, a first-first ohmic electrode 3290a, a first-second ohmic electrode 3290b, and a second LED stack 3330. 90b, a second-1 ohmic electrode 3390, a second-2 ohmic electrode 3350, a third-1 ohmic electrode 3490, a third-2 ohmic electrode 3450, a first bonding layer 3530, a second bonding layer 3550, an upper insulating layer 3610, connectors 3710, 3720 and 3730, a lower insulating layer 3750, and electrode pads 3770a, 3770b, 3770c and 3770d.

[0423] Each of the R, G, and B subpixels includes an LED stack 3230, 3330, and 3430 and an ohmic electrode. The anodes of the first, second, and third subpixels R, G, and B are electrically connected to electrode pads 3770a, 3770b, and 3770c, respectively, and the cathodes are electrically connected to electrode pad 3770d, thereby allowing the first, second, and third subpixels R, G, and B to be driven independently.

[0424] The substrate 3210 supports the LED stacks 3230, 3330, and 3430. The substrate 3210 may be a growth substrate, such as a GaAs substrate, on which an AlGaInP-based semiconductor layer can be grown. In particular, the substrate 3210 may be a semiconductor substrate exhibiting n-type conductivity.

[0425] The first LED stack 3230 includes a first conductivity type semiconductor layer 3230a and a second conductivity type semiconductor layer 3230b, the second LED stack 3330 includes a first conductivity type semiconductor layer 3330a and a second conductivity type semiconductor layer 3330b, and the third LED stack 3430 includes a first conductivity type semiconductor layer 3430a and a second conductivity type semiconductor layer 3430b. An active layer may be interposed between the first conductivity type semiconductor layer 3230a, 3330a, or 3430a and the second conductivity type semiconductor layer 3230b, 3330b, or 3430b.

[0426] According to an exemplary embodiment, each of the first conductivity type semiconductor layers 3230a, 3330a, and 3430a may be an n-type semiconductor layer, and each of the second conductivity type semiconductor layers 3230b, 3330b, and 3430b may be a p-type semiconductor layer. A roughened surface is formed on the upper surface of each of the first conductivity type semiconductor layers 3230a, 3330a, and 3430a by surface texturing. However, the concept of the present invention is not limited thereto, and the first and second conductivity types may be reversed.

[0427] The first LED stack 3230 is disposed near the support substrate 3510, the second LED stack 3330 is disposed on the first LED stack 3230, and the third LED stack 3430 is disposed on the second LED stack 3330. The second LED stack 3330 is disposed in a partial region on the first LED stack 3230, and the first LED stack 3230 partially overlaps the second LED stack 3330. The third LED stack 3430 is disposed in a partial region on the second LED stack 3330, and the second LED stack 3330 partially overlaps the third LED stack 3430. Therefore, light generated from the first LED stack 3230 is emitted to the outside without passing through the second and third LED stacks 3330 and 3430. Furthermore, light generated from the second LED stack 3330 is emitted to the outside without passing through the third LED stack 3430.

[0428] The materials of the first LED stack 3230, the second LED stack 3330 and the third LED stack 3430 are substantially the same as those described with reference to FIG. 57, and therefore detailed descriptions thereof will be omitted to avoid duplication.

[0429] A distributed Bragg reflector 3220 is interposed between the substrate 3210 and the first LED stack 3230. The distributed Bragg reflector 3220 may include semiconductor layers grown on the substrate 3210. For example, the distributed Bragg reflector 3220 may be formed by stacking alternating AlAs and AlGaAs layers. The distributed Bragg reflector 3220 may include semiconductor layers that electrically connect the substrate 3210 to the first conductivity type semiconductor layer 3230a of the first LED stack 3230.

[0430] Through-hole vias 3270a, 3270b, and 3270c are formed through substrate 3210. Through-hole vias 3270a, 3270b, and 3270c are formed through first LED stack 3230. Through-hole vias 3270a, 3270b, and 3270c are formed with a conductive paste or by plating.

[0431] The insulating layer 3250 is disposed between the through-hole vias 3270a, 3270b and 3270c and the inner walls of the through-holes formed through the substrate 3210 and the first LED stack 3230 to prevent short circuits between the first LED stack 3230 and the substrate 3210.

[0432] The 1-1 ohmic electrode 3390a forms an ohmic contact with the first conductivity type semiconductor layer 3230a of the first LED stack 3230. The 1-1 ohmic electrode 3290a is formed of, for example, an Au—Te or Au—Ge alloy.

[0433] To form the first-first ohmic electrode 3290a, the second conductive type semiconductor layer 3230b and the active layer may be partially removed to expose the first conductive type semiconductor layer 3230a. The first-first ohmic electrode 3290a is disposed apart from the region where the second LED stack 3330 is disposed. The first-first ohmic electrode 3290 may also include a pad region and an extension, and the connector 3710 is connected to the pad region of the first-first ohmic electrode 3290, as shown in FIG. 59A .

[0434] The first-second ohmic electrode 3390b forms ohmic contact with the second conductive type semiconductor layer 3230b of the first LED stack 3230. As shown in FIG. 59A , the first-second ohmic electrode 3290b is formed to partially surround the first-first ohmic electrode 3290a to aid current spreading. The first-second ohmic electrode 3290b may not include an extension. The first-second ohmic electrode 3290b may be formed of, for example, an Au-Zn or Au-Be alloy. The first-second ohmic electrode 3290b may have a single-layer or multi-layer structure.

[0435] The first-second ohmic electrode 3290b is connected to the through-hole via 3270a so that the through-hole via 3270a is electrically connected to the second conductivity type semiconductor layer 3230b.

[0436] The 2-1 ohmic electrode 3390 forms ohmic contact with the first conductivity type semiconductor layer 3330a of the second LED stack 3330. The 2-1 ohmic electrode 3390 may further include a pad region and an extension. As shown in FIG. 59A , a connector 3710 can electrically connect the 2-1 ohmic electrode 3390 to the 1-1 ohmic electrode 3290a. The 2-1 ohmic electrode 3390 is disposed apart from the region where the third LED stack 3430 is disposed.

[0437] The second-second ohmic electrode 3350 forms ohmic contact with the second conductive type semiconductor layer 3330b of the second LED stack 3330. The second-second ohmic electrode 3350 may include a reflective layer 3350a and a barrier layer 3350b. The reflective layer 3350a reflects light generated from the second LED stack 3330 to improve the luminous efficiency of the second LED stack 3330. The barrier layer 3350b may serve as a connection pad for providing the reflective layer 3350a and is connected to the connector 3720. Although the second-second ohmic electrode 3350 is described as including a metal layer in this illustrative embodiment, the concept of the present invention is not limited thereto. For example, the second-second ohmic electrode 3350 may be formed of a transparent conductive oxide, such as a conductive oxide semiconductor layer.

[0438] The third-1 ohmic electrode 3490 forms an ohmic contact with the first conductivity type semiconductor layer 3430a of the third LED stack 3430. The third-1 ohmic electrode 3490 may further include a pad region and an extension, and a connector 3710 connects the third-1 ohmic electrode 3490 to the first-1 ohmic electrode 3290a, as shown in FIG.

[0439] The third-second ohmic electrode 3450 may form ohmic contact with the second conductive type semiconductor layer 3430b of the third LED stack 3430. The third-second ohmic electrode 3450 may include a reflective layer 3450a and a barrier layer 3450b. The reflective layer 3450a reflects light generated from the third LED stack 3430 to improve the luminous efficiency of the third LED stack 3430. The barrier layer 3450b may serve as a connection pad for providing the reflective layer 3450a and may be connected to the connector 3730. Although the third-second ohmic electrode 3450 is described as including a metal layer, the concept of the present invention is not limited thereto. Alternatively, the third-second ohmic electrode 3450 may be formed of a transparent conductive oxide, such as a conductive oxide semiconductor layer.

[0440] The first-2 ohmic electrode 3290b, the second-2 ohmic electrode 3350, and the third-2 ohmic electrode 3450 can form ohmic contacts with the p-type semiconductor layers of the corresponding LED stacks to aid in current spreading, and the first-1 ohmic electrode 3290a, the second-1 ohmic electrode 3390, and the third-1 ohmic electrode 3490 can form ohmic contacts with the n-type semiconductor layers of the corresponding LED stacks to aid in current spreading.

[0441] The first bonding layer 3530 bonds the second LED stack 3330 to the first LED stack 3230. As shown, a second ohmic electrode 3350 may be adjacent to the first bonding layer 3530. The first bonding layer 3530 may be an optically transparent layer or an opaque layer. The first bonding layer 3530 may be formed of an organic or inorganic material. Examples of organic materials may include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc., while examples of inorganic materials include Al2O3, SiO2, SiN x The first bonding layer 3530 may include, for example, a first LED stack 3230, a second LED stack 3230, a third LED stack 3230, a fourth LED stack 3230, a fourth LED stack 3230, a fifth LED stack 3230, a sixth ...

[0442] The second bonding layer 3550 couples the second LED stack 3330 to the third LED stack 3430. The second bonding layer 3550 is interposed between the second LED stack 3330 and the third-second ohmic electrode 3450 and can bond the second LED stack 3330 to the third-second ohmic electrode 3450. The second bonding layer 3550 is formed of substantially the same bonding material as the first bonding layer 3530. Additionally, an insulating layer and / or a reflective layer may be additionally disposed between the second LED stack 3330 and the second bonding layer 3550.

[0443] When the first bonding layer 3530 and the second bonding layer 3550 are formed of a light-transmitting material and the second-second ohmic electrode 3350 and the third-second ohmic electrode 3450 are formed of a transparent oxide material, a portion of the light generated from the first LED stack 3230 may be emitted through the second LED stack 3330 after penetrating the first bonding layer 3530 and the second-second ohmic electrode 3350, and may further be emitted through the third LED stack 3430 after penetrating the second bonding layer 3550 and the third-second ohmic electrode 3450. At the same time, a portion of the light generated from the second LED stack 3330 may be emitted through the third LED stack 3430 after penetrating the second bonding layer 3550 and the third-second ohmic electrode 3450.

[0444] In this case, the light generated from the first LED stack 3230 must be prevented from being absorbed by the second LED stack 3330 while passing through the second LED stack 3330. In this manner, the light generated from the first LED stack 3230 may have a smaller bandgap than the second LED stack 3330, and therefore may have a longer wavelength than the light generated from the second LED stack 3330.

[0445] At the same time, the light generated from the second LED stack 3330 may have a longer wavelength than the light generated from the third LED stack 3430 to prevent the light generated from the second LED stack 3330 from being absorbed by the third LED stack 3430 while passing through the third LED stack 3430.

[0446] When the first bonding layer 3530 and the second bonding layer 3550 are formed of an opaque material, the reflective layer is interposed between the first LED stack 3230 and the first bonding layer 3530 and between the second LED stack 3330 and the second bonding layer 3550, respectively, and reflects light generated from the first LED stack 3230 and entering the first bonding layer 3530, and light generated from the second LED stack 3330 and entering the second bonding layer 3550. The reflected light is emitted through the first LED stack 3230 and the second LED stack 3330.

[0447] The upper insulating layer 3610 can cover the first to third LED stacks 3230, 3330, and 3430. In particular, the upper insulating layer 3610 can cover the side surfaces of the second LED stack 3330 and the third LED stack 3430, and can also cover the side surface of the first LED stack 3230.

[0448] The upper insulating layer 3610 has openings that expose the first to third through-hole vias 3270a, 3270b, and 3270c, and openings that expose the first conductivity type semiconductor layer 3330a of the second LED stack 3330, the first conductivity type semiconductor layer 3430a of the third LED stack 3430, the 2-2 ohmic electrode 3350, and the 3-2 ohmic electrode 3450.

[0449] The top insulating layer 3610 may be formed of any insulating material, such as, but not limited to, silicon oxide or silicon nitride.

[0450] The connector 3710 electrically connects the first-1 ohmic electrode 3290a, the second-1 ohmic electrode 3390, and the third-1 ohmic electrode 3490 to one another. The connector 3710 is formed on the upper insulating layer 3610 and is insulated from the second conductivity type semiconductor layer 3430b of the third LED stack 3430, the second conductivity type semiconductor layer 3330b of the second LED stack 3330, and the second conductivity type semiconductor layer 3230b of the first LED stack 3230.

[0451] The connector 3710 is formed of substantially the same material as the 2-1 ohmic electrode 3390 and the 3-1 ohmic electrode 3490, and therefore is formed together with the 2-1 ohmic electrode 3390 and the 3-1 ohmic electrode 3390. Alternatively, the connector 3710 is formed of a different conductive material from the 2-1 ohmic electrode 3390 or the 3-1 ohmic electrode 3490, and therefore may be formed separately in a different process from the 2-1 ohmic electrode 3390 and / or the 3-1 ohmic electrode 3490.

[0452] The connector 3720 can electrically connect the second-1 ohmic electrode 3350, e.g., the barrier layer 3350b, to the second through-hole via 3270b. The connector 3730 electrically connects the third-1 ohmic electrode, e.g., the barrier layer 3450b, to the third through-hole via 3270c. The connector 3720 is electrically insulated from the first LED stack 3230 by the upper insulating layer 3610. The connector 3730 is electrically insulated from the second LED stack 3330 and the first LED stack 3230 by the upper insulating layer 3610.

[0453] The connectors 3720 and 3730 are formed together using the same process. The connectors 3720 and 3730 are further formed together with the connector 3710. The connectors 3720 and 3730 may also be formed from substantially the same material as the second-first ohmic electrode 3390 and the third-first ohmic electrode 3490 and may be formed together. Alternatively, the connectors 3720 and 3730 may be formed from a different conductive material than the second-first ohmic electrode 3390 or the third-first ohmic electrode 3490, and therefore may be formed separately using a different process than the second-first ohmic electrode 3390 and / or the third-first ohmic electrode 3490.

[0454] The lower insulating layer 3750 covers the lower surface of the substrate 3210. The lower insulating layer 3750 may include openings that expose the first to third through-hole vias 3270a, 3270b, and 3270c on the lower side of the substrate 3210, and may also include openings that expose the lower surface of the substrate 3210.

[0455] Electrode pads 3770a, 3770b, 3770c, and 3770d are disposed on the lower surface of substrate 3210. Electrode pads 3770a, 3770b, and 3770c are connected to through-hole vias 3270a, 3270b, and 3270c through openings in insulating layer 3750, and electrode pad 3770d is connected to substrate 3210.

[0456] Electrode pads 3770a, 3770b, and 3770c are provided at each pixel to be electrically connected to the first, second, and third LED stacks 3230, 3330, and 3430 of each pixel, respectively. An electrode pad 3770d may also be provided at each pixel, but the substrate 3210 may be disposed continuously over a plurality of pixels, which may obviate the need to provide an electrode pad 3770d at each pixel.

[0457] The electrode pads 3770a, 3770b, 3770c and 3770d are bonded to the circuit board 3510, thereby providing a display device.

[0458] Next, a method for manufacturing a display device according to an exemplary embodiment will be described.

[0459] 61A to 68B are schematic plan views and cross-sectional views illustrating a method of manufacturing a display device according to an example embodiment, each cross-sectional view being taken along a line shown in the corresponding plan view.

[0460] 61A and 61B, a first LED stack 3230 is grown on a substrate 3210. The substrate 3210 may be, for example, a GaAs substrate. The first LED stack 3230 is formed of an AlGaInP-based semiconductor layer and includes a first conductivity type semiconductor layer 3230a, an active layer, and a second conductivity type semiconductor layer 3230b. The distributed Bragg reflector 3220 may be formed before the growth of the first LED stack 3230. The distributed Bragg reflector 3220 may have a stack structure formed by repeatedly stacking AlAs / AlGaAs layers, for example.

[0461] Thereafter, grooves are formed on the first LED stack 3230 and the substrate 3210 by photolithography and etching. The grooves may be formed all the way through the substrate 3210, as shown in FIG. 61B, or may be formed to a predetermined depth within the substrate 3210.

[0462] An insulating layer 3250 is then formed to cover the sidewalls of the trenches, and through-hole vias 3270a, 3270b, and 3270c are formed to fill the trenches. Through-hole vias 3270a, 3270b, and 3270c can be formed, for example, by forming an insulating layer to cover the sidewalls of the trenches, filling the trenches with a layer of conductive material or a conductive paste by plating, and removing the insulating layer and the layer of conductive material from the top surface of first LED stack 3230 by chemical-mechanical polishing.

[0463] 62A and 62B, the second LED stack 3330 and the second ohmic electrode 3350 are coupled to the first LED stack 3230 via the first bonding layer 3530. Referring to FIG.

[0464] The second LED stack 3330 is grown on a second substrate, and a second-second ohmic electrode 3350 is formed on the second LED stack 3330. The second LED stack 3330 is formed of an AlGaInP-based or AlGaInN-based semiconductor layer and may include a first-conductivity-type semiconductor layer 3330a, an active layer, and a second-conductivity-type semiconductor layer 3330b. The second substrate may be a substrate on which an AlGaInP-based semiconductor layer can be grown, such as a GaAs substrate, or a substrate on which an AlGaInN-based semiconductor layer can be grown, such as a sapphire substrate. The Al, Ga, and In composition ratio for the second LED stack 3330 may be determined so that the second LED stack 3330 can emit green light. The second-second ohmic electrode 3350 forms an ohmic contact with the second-conductivity-type semiconductor layer 3330b, such as a p-type semiconductor layer. The second-2 ohmic electrode 3350 may include a reflective layer 3350a that reflects light generated from the second LED stack 3330, and a barrier layer 3350b.

[0465] The second-second ohmic electrode 3350 is disposed facing the first LED stack 3230 and is bonded to the first LED stack 3230 by a first bonding layer 3530. The second substrate is then removed from the second LED stack 3330 by chemical etching or laser lift-off to expose the first conductivity type semiconductor layer 3330a. A roughened surface is formed on the exposed first conductivity type semiconductor layer 3330a by surface texturing.

[0466] According to an example embodiment, an insulating layer and a reflective layer may be additionally formed on the first LED stack 3230 before the formation of the first bonding layer 3530 .

[0467] 63A and 63B, the third LED stack 3430 and the third-2 ohmic electrode 3450 are coupled to the second LED stack 3330 via a second bonding layer 3550. Referring to FIG.

[0468] The third LED stack 3430 is grown on a third substrate, and a third-second ohmic electrode 3450 is formed on the third LED stack 3430. The third LED stack 3430 is formed of an AlGaInN-based semiconductor layer and may include a first conductivity type semiconductor layer 3430a, an active layer, and a second conductivity type semiconductor layer 3430b. The third substrate is a substrate on which a GaN-based semiconductor layer can be grown and is different from the first substrate 3210. The AlGaInN composition ratio for the third LED stack 3430 may be determined so that the third LED stack 3430 can emit blue light. The third-second ohmic electrode 3450 forms an ohmic contact with the second conductivity type semiconductor layer 3430b, for example, a p-type semiconductor layer. The third-second ohmic electrode 3450 may include a reflective layer 3450a that reflects light generated from the third LED stack 3430 and a barrier layer 3450b.

[0469] The third-2 ohmic electrode 3450 is disposed facing the second LED stack 3330 and is bonded to the second LED stack 3330 by a second bonding layer 3550. The third substrate is then removed from the third LED stack 3430 by chemical etching or laser lift-off to expose the first conductivity type semiconductor layer 3430a. A roughened surface is formed on the exposed first conductivity type semiconductor layer 3430a by surface texturing.

[0470] According to an example embodiment, an insulating layer and a reflective layer may be additionally formed on the second LED stack 3330 before the formation of the second bonding layer 3550 .

[0471] 64A and 64B, in each pixel region, the third LED stack 3430 is patterned to remove the third LED stack 3430 except for the third subpixel B. In the region of the third subpixel B, an indentation is formed on the third LED stack 3430 to expose the barrier layer 3450b through the indentation.

[0472] Thereafter, the third-2 ohmic electrode 3450 and the second bonding layer 3550 are removed in the region other than the third subpixel B to expose the second LED stack 3330. In this manner, the third-2 ohmic electrode 3450 is disposed in a limited manner near the third subpixel B region.

[0473] In each pixel area, the second LED stack 3330 is patterned to remove the second LED stack 3330 in areas other than the second subpixel G. In the area of ​​the second subpixel G, the second LED stack 3330 partially overlaps with the third LED stack 3430.

[0474] The second LED stack 3330 is patterned to expose the second-second ohmic electrode 3350. The second LED stack 3330 may include an indentation, and the second-second ohmic electrode 3350, for example, the barrier layer 3350b, may be exposed through the indentation.

[0475] Thereafter, the 2-2 ohmic electrode 3350 and the first bonding layer 3530 are removed to expose the first LED stack 3230. In this manner, the 2-2 ohmic electrode 3350 is disposed near the region of the second subpixel G. Meanwhile, the first to third through-hole vias 3270a, 3270b, and 3270c are also exposed along with the first LED stack 3230.

[0476] In each pixel region, the first conductive type semiconductor layer 3230a is exposed by patterning the second conductive type semiconductor layer 3230b of the first LED stack 3230. As shown in FIG. 64A, the first conductive type semiconductor layer 3230a may be exposed in an elongated shape, but is not limited thereto.

[0477] Furthermore, the pixel regions are divided from one another by patterning the first LED stack 3230. In this way, the regions of the first subpixels R are formed. Here, the distributed Bragg reflector 3220 may be further divided. Alternatively, the distributed Bragg reflector 3220 may be disposed continuously over multiple pixels without being divided. Furthermore, the first conductive type semiconductor layer 3230a may also be disposed continuously over multiple pixels.

[0478] 65A and 65B, a first-1 ohmic electrode 3290a and a second-2 ohmic electrode 3290b are formed on the first LED stack 3230. The first-1 ohmic electrode 3290a is formed of, for example, an Au-Te or Au-Ge alloy on the exposed first conductivity type semiconductor layer 3230a. The first-2 ohmic electrode 3290b is formed of, for example, an Au-Be or Au-Zn alloy on the second conductivity type semiconductor layer 3230b. The first-2 ohmic electrode 3290b may be formed before the first-1 ohmic electrode 3290a, or vice versa. The first-2 ohmic electrode 3290b is connected to the first through-hole via 3270a. Meanwhile, the first-1 ohmic electrode 3290a may include a pad region and an extension extending from the pad region toward the first through-hole via 3270a.

[0479] For current spreading, the first-second ohmic electrode 3290b is disposed to at least partially surround the first-first ohmic electrode 3290a. Although each of the first-first ohmic electrode 3290a and the first-second ohmic electrode 3290b is shown in FIG. 65A as having an elongated shape, the concept of the present invention is not limited in this respect. Alternatively, each of the first-first ohmic electrode 3290a and the first-second ohmic electrode 3290b may have, for example, a circular shape.

[0480] 66A and 66B, an upper insulating layer 3610 is formed to cover the first to third LED stacks 3230, 3330, and 3430. The upper insulating layer 3610 may cover the first to second ohmic electrodes 3390a and 3290b. The upper insulating layer 3610 may further cover the side surfaces of the first to third LED stacks 3230, 3330, and 3430 and the side surface of the distributed Bragg reflector 3220.

[0481] The upper insulating layer 3610 may have an opening 3610a exposing the first-1 ohmic electrode 3290a, openings 3610b and 3610c exposing the barrier layers 3350b and 3450b, openings 3610d and 3610e exposing the second and third through-hole vias 3270b and 3270c, and openings 3610f and 3610g exposing the first conductivity type semiconductor layers 3330a and 3430a of the second LED stack 3330 and the third LED stack 3430.

[0482] 67A and 67B, a second-first ohmic electrode 3390, a third-first ohmic electrode 3490, and connectors 3710, 3720, and 3730 are formed. The second-first ohmic electrode 3390 is formed in the opening 3610f to form ohmic contact with the first conductivity type semiconductor layer 3330a, and the third-first ohmic electrode 3490 is formed in the opening 3610g to form ohmic contact with the first conductivity type semiconductor layer 3430a.

[0483] The connector 3710 electrically connects the second-first ohmic electrode 3390 and the third-first ohmic electrode 3490 to the first-first ohmic electrode 3290a. The connector 3710 is connected to the first-first ohmic electrode 3290a exposed in the opening 3610a, for example. The connector 3710 is formed on the upper insulating layer 3610 so as to be insulated from the second conductivity type semiconductor layers 3230b, 3330b, and 3430b.

[0484] The connector 3720 electrically connects the 2-2 ohmic electrode 3350 to the second through-hole via 3270b, and the connector 3730 electrically connects the 3-2 ohmic electrode 3450 to the third through-hole via 3270c. The connectors 3720 and 3730 are disposed on the upper insulating layer 3610 to prevent short circuits between the first to third LED stacks 3230, 3330, and 3430.

[0485] The 2-1 ohmic electrode 3390, the 3-1 ohmic electrode 3490, and the connectors 3710, 3720, and 3730 are formed from substantially the same material using the same process. However, the concept of the present invention is not limited to this. Alternatively, the 2-1 ohmic electrode 3390, the 3-1 ohmic electrode 3490, and the connectors 3710, 3720, and 3730 may be formed from different materials using different processes.

[0486] 68A and 68B, a lower insulating layer 3750 is formed on the lower surface of the substrate 3210. The lower insulating layer 3750 has openings that expose the first to third through-hole vias 3270a, 3270b, and 3270c, and may also have openings that expose the lower surface of the substrate 3210.

[0487] Electrode pads 3770a, 3770b, 3770c, and 3770d are formed on the lower insulating layer 3750. The electrode pads 3770a, 3770b, and 3770c are connected to the first to third through-hole vias 3270a, 3270b, and 3270c, respectively, and the electrode pad 3770d is connected to the substrate 3210.

[0488] Therefore, the electrode pad 3770a is electrically connected to the second conductivity type semiconductor layer 3230b of the first LED stack 3230 via the first through-hole via 3270a, the electrode pad 3770b is electrically connected to the second conductivity type semiconductor layer 3330b of the second LED stack 3330 via the second through-hole via 3270b, and the electrode pad 3770c is electrically connected to the second conductivity type semiconductor layer 3430b of the third LED stack 3430 via the third through-hole via 3270c. The first conductivity type semiconductor layers 3230a, 3330a, and 3430a of the first to third LED stacks 3230, 3330, and 3430 are electrically connected in common to the electrode pad 3770d.

[0489] In this manner, a display device according to an exemplary embodiment can be formed by bonding electrode pads 3770a, 3770b, 3770c, and 3770d of substrate 3210 to circuit board 3510 shown in Figure 56. As previously mentioned, circuit board 3510 can include active or passive circuitry, allowing the display device to be driven in either an active matrix or passive matrix manner.

[0490] FIG. 69 is a cross-sectional view of a light emitting diode pixel for a display according to another exemplary embodiment.

[0491] 69, a light emitting diode pixel 3001 of a display device according to an exemplary embodiment is generally similar to the light emitting diode pixel 3000 of the display device of FIG. 57, except that the second LED stack 3330 covers most of the first LED stack 3230, and the third LED stack 3430 covers most of the second LED stack 3330. In this manner, light generated from the first subpixel R is emitted to the outside after substantially passing through the second LED stack 3330 and the third LED stack 3430, and light generated from the second LED stack 3330 is emitted to the outside after substantially passing through the third LED stack 3430.

[0492] The first LED stack 3230 may include an active layer having a narrower bandgap than the second LED stack 3330 and the third LED stack 3430 so as to emit light having a longer wavelength than the second LED stack 3330 and the third LED stack 3430, and the second LED stack 3330 may include an active layer having a narrower bandgap than the third LED stack 3430 so as to emit light having a longer wavelength than the third LED stack 3430.

[0493] FIG. 70 is an enlarged plan view of one pixel of a display device according to an exemplary embodiment, and FIGS. 71A and 71B are cross-sectional views taken along lines GG and HH in FIG. 70, respectively.

[0494] 70, 71A, and 71B, a pixel according to an example embodiment is generally similar to the pixel of FIGS. 59, 60A, 60B, and 60C, except that the second LED stack 3330 covers most of the first LED stack 3230, and the third LED stack 3430 covers most of the second LED stack 3330. First, second, and third through-hole vias 3270a, 3270b, and 3270c are disposed outside the second LED stack 3330 and the third LED stack 3430.

[0495] At the same time, a portion of the 1-1 ohmic electrode 3290a and a portion of the 2-1 ohmic electrode 3390 are disposed below the third LED stack 3430. In this manner, the 1-1 ohmic electrode 3290a may be formed before the second LED stack 3330 is bonded to the first LED stack 3230, and the 2-1 ohmic electrode 3390 may also be formed before the third LED stack 3430 is bonded to the second LED stack 3330.

[0496] Furthermore, light generated from the first LED stack 3230 is emitted to the outside after substantially penetrating the second LED stack 3330 and the third LED stack 3430, and light generated from the second LED stack 3330 is emitted to the outside after substantially penetrating the third LED stack 3430. Therefore, the first bonding layer 3530 and the second bonding layer 3550 are formed of a light-transmitting material, and the second-second ohmic electrode 3350 and the third-second ohmic electrode 3450 are composed of a transparent conductive layer.

[0497] 71A and 71B , an indentation may be formed on the third LED stack 3430 to expose the 3-2 ohmic electrode 3450, and an indentation may be formed continuously on the third LED stack 3430 and the second LED stack 3330 to expose the 2-2 ohmic electrode 3350. The 2-2 ohmic electrode 3350 and the 3-2 ohmic electrode 3450 are electrically connected to the second through-hole via 3270b and the third through-hole via 3270c via connectors 3720 and 3730, respectively.

[0498] Further, the indentation is formed on the third LED stack 3430 to expose the 2-1 ohmic electrode 3390 formed on the first conductivity type semiconductor layer 3330a of the second LED stack 3330, and the indentation is continuously formed on the third LED stack 3430 and the second LED stack 3330 to expose the 1-1 ohmic electrode 3290a formed on the first conductivity type semiconductor layer 3230a of the first LED stack 3230. The connector 3710 can connect the 1-1 ohmic electrode 3290a and the 2-1 ohmic electrode 3390 to the 3-1 ohmic electrode 3490. The 3-1 ohmic electrode 3490 is formed together with the connector 3710 and is connected to pad regions of the 1-1 ohmic electrode 3290a and the 2-1 ohmic electrode 3390.

[0499] Although the first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390 are partially disposed below the third LED stack 3430, the concept of the present invention is not limited thereto. For example, the portions of the first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390 disposed below the third LED stack 3430 may be omitted. Alternatively, the second-1 ohmic electrode 3390 may be omitted, and the connector 3710 may form ohmic contact with the first conductivity type semiconductor layer 3330a.

[0500] According to an exemplary embodiment, the pixels are formed at the wafer level by wafer bonding, so that the process of individually packaging the light emitting diodes can be eliminated or substantially reduced.

[0501] Also, because through-hole vias 3270a, 3270b, and 3270c are formed in substrate 3210 and used as current paths, substrate 3210 does not need to be removed. Thus, the growth substrate used for growing first LED stack 3230 can be used as substrate 3210 without being removed from first LED stack 3230.

[0502] FIG. 72 is a schematic cross-sectional view of a light emitting diode (LED) stack for a display according to an example embodiment.

[0503] Referring to Figure 72, a light-emitting diode stack 4000 for a display may include a support substrate 4051, a first LED stack 4023, a second LED stack 4033, a third LED stack 4043, a reflective electrode 4025, an ohmic electrode 4026, a first insulating layer 4027, a second insulating layer 4028, an interconnection line 4029, a second-p transparent electrode 4035, a third-p transparent electrode 4045, a first color filter 4037, a second color filter 4047, hydrophilic material layers 4052, 4054 and 4056, a first bonding layer (lower bonding layer) 4053, a second bonding layer (middle bonding layer) 4055 and a third bonding layer (upper bonding layer) 4057.

[0504] Support substrate 4051 supports semiconductor stacks 4023, 4033, and 4043. Support substrate 4051 can have circuitry on or within its surface, but is not limited to such. Support substrate 4051 can include, for example, glass, a sapphire substrate, a Si substrate, or a Ge substrate.

[0505] The first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 include first conductivity type semiconductor layers 4023a, 4033a, and 4043a, second conductivity type semiconductor layers 4023b, 4033b, and 4043b, respectively, and an active layer interposed between the first conductivity type semiconductor layers and the second conductivity type semiconductor layers. The active layer may have a multiple quantum well structure.

[0506] The first LED stack 4023 may be an inorganic LED that emits red light, the second LED stack 4033 may be an inorganic LED that emits green light, and the third LED stack 4043 may be an inorganic LED that emits blue light. The first LED stack 4023 may include a GaInP-based well layer, and the second LED stack 4033 and the third LED stack 4043 may include GaInN-based well layers. However, the concept of the present invention is not limited in this respect. If the LED stacks include micro LEDs, the first LED stack 4023 may emit any one of red, green, and blue light, and the second and third LED stacks 4033 and 4043 may emit the other one of red, green, and blue light due to their small form factors without adversely affecting operation or requiring a color filter.

[0507] The opposing surfaces of each LED stack 4023, 4033, or 4043 are n-type and p-type semiconductor layers, respectively. In the illustrated exemplary embodiment, the first conductivity type semiconductor layers 4023a, 4033a, and 4043a of the first to third LED stacks 4023, 4033, and 4043, respectively, are n-type, and the second conductivity type semiconductor layers 4023b, 4033b, and 4043b are p-type. Roughened surfaces are formed on the top surfaces of the first to third LED stacks 4023, 4033, and 4043. However, the concept of the present invention is not limited in this respect, and the semiconductor types of the top and bottom surfaces of each LED stack may be reversed.

[0508] The first LED stack 4023 is disposed adjacent to the support substrate 4051, the second LED stack 4033 is disposed on the first LED stack 4023, and the third LED stack 4043 is disposed on the second LED stack 4033. Because the first LED stack 4023 emits light with a longer wavelength than the second and third LED stacks 4033 and 4043, light generated in the first LED stack 4023 is transmitted through the second and third LED stacks 4033 and 4043 and emitted to the outside. In addition, because the second LED stack 4033 emits light with a longer wavelength than the third LED stack 4043, light generated in the second LED stack 4033 is transmitted through the third LED stack 4043 and emitted to the outside.

[0509] The reflective electrode 4025 is in ohmic contact with the second conductive type semiconductor layer of the first LED stack 4023 and reflects light generated in the first LED stack 4023. For example, the reflective electrode 4025 may include an ohmic contact layer 4025a and a reflective layer 4025b.

[0510] The ohmic contact layer 4025a is in partial contact with the second conductive type semiconductor layer, i.e., the p-type semiconductor layer. To prevent light absorption by the ohmic contact layer 4025a, the area where the ohmic contact layer 4025a contacts the p-type semiconductor layer may not exceed approximately 50% of the entire area of ​​the p-type semiconductor layer. The reflective layer 4025b covers the ohmic contact layer 4025a and the first insulating layer 4027. As shown in the figure, the reflective layer 4025b can substantially cover the entire ohmic contact layer 4025a or a portion of the ohmic contact layer 4025a.

[0511] The reflective layer 4025b covers the first insulating layer 4027, so that an omnidirectional reflector is formed by a stack of the first LED stack 4023 having a relatively high refractive index, the first insulating layer 4027 having a relatively low refractive index, and the reflective layer 4025b. The reflective layer 4025b covers more than 50% of the area of ​​the first LED stack 4023 or most of the area of ​​the first LED stack 4023, thereby improving light efficiency.

[0512] The ohmic contact layer 4025a and the reflective layer 4025b are formed of a metal layer containing gold (Au). The ohmic contact layer 4025a is formed of, for example, an Au-Zn alloy or an Au-Be alloy. The reflective layer 4025b is formed of a metal layer such as aluminum (Al), silver (Ag), or gold (Au), which has a high reflectivity for light generated in the first LED stack 4023, such as red light. In particular, gold (Au) may have a relatively low reflectivity for light generated in the second LED stack 4033 and the third LED stack 4043, such as green light or blue light, and therefore can reduce optical interference by absorbing light generated in the second and third LED stacks 4033 and 4043 and traveling toward the support substrate 4051.

[0513] The first insulating layer 4027 is disposed between the support substrate 4051 and the first LED stack 4023 and has an opening exposing the first LED stack 4023. The ohmic contact layer 4025a is connected to the first LED stack 4023 in the opening of the first insulating layer 4023.

[0514] The ohmic electrode 4026 makes ohmic contact with the first conductivity type semiconductor layer 4023a of the first LED stack 4023. The ohmic electrode 4026 is disposed on the first conductivity type semiconductor layer 4023a that is exposed by partially removing the second conductivity type semiconductor layer 4023b. Although FIG. 72 illustrates one ohmic electrode 4026, multiple ohmic electrodes 4026 may be arranged on multiple regions on the support substrate 4051. The ohmic electrode 4026 is formed of, for example, an Au—Te alloy or an Au—Ge alloy.

[0515] The second insulating layer 4028 is disposed between the support substrate 4051 and the reflective electrode 4025 and covers the reflective electrode 4025. The second insulating layer 4028 has an opening that exposes the ohmic electrode 4026. The second insulating layer 4028 is formed of SiO2 or SOG.

[0516] The interconnection line 4029 is disposed between the second insulating layer 4028 and the support substrate 4051, and is connected to the ohmic electrode 4026 through an opening in the second insulating layer 4028. The interconnection line 4026 can connect multiple ohmic electrodes 4026 to each other on the support substrate 4051.

[0517] The second-p transparent electrode 4035 is in ohmic contact with the second conductivity type semiconductor layer 4033b, i.e., the p-type semiconductor layer, of the second LED stack 4033. The second-p transparent electrode 4035 is formed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0518] The third-p transparent electrode 4045 is in ohmic contact with the second conductive type semiconductor layer 4043b, i.e., the p-type semiconductor layer, of the third LED stack 4043. The third-p transparent electrode 4045 is formed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0519] The reflective electrode 4025, the second-p transparent electrode 4035 and the third-p transparent electrode 4045 can make ohmic contact with the p-type semiconductor layer of each LED stack to aid in current spreading.

[0520] The first color filter 4037 is disposed between the first LED stack 4023 and the second LED stack 4033. In addition, the second color filter 4047 is disposed between the second LED stack 4033 and the third LED stack 4043. The first color filter 4037 transmits light generated in the first LED stack 4023 and reflects light generated in the second LED stack 4033. The second color filter 4047 transmits light generated in the first and second LED stacks 4023 and 4033 and reflects light generated in the third LED stack 4043. Therefore, the light generated in the first LED stack 4023 is emitted to the outside via the second LED stack 4033 and the third LED stack 4043, and the light generated in the second LED stack 4033 is emitted to the outside via the third LED stack 4043. It is also possible to prevent light generated in the second LED stack 4033 from being incident on the first LED stack 4023 and being lost, or light generated in the third LED stack 4043 from being incident on the second LED stack 4033 and being lost.

[0521] According to some demonstrative embodiments, the first color filter 4037 may further reflect light generated by the third LED stack 4043. According to some demonstrative embodiments, if the LED stack includes micro LEDs, the color filter may be omitted due to the small form factor of the micro LEDs.

[0522] The first and second color filters 4037 and 4047 may be, for example, low-pass filters that pass only low-frequency (i.e., long-wavelength) wavelengths, band-pass filters that pass only a predetermined wavelength band, or band-stop filters that block only a predetermined wavelength band. In particular, the first and second color filters 4037 and 4047 can be formed by alternately stacking insulating layers having different refractive indices, such as TiO2 and SiO2, Ta2O5 and SiO2, Nb2O5 and SiO2, HfO2 and SiO2, or ZrO2 and SiO2. The first and / or second color filters 4037 and / or 4047 can also include a distributed Bragg reflector (DBR). The distributed Bragg reflector can be formed by alternately stacking insulating layers having different refractive indices. The stopband of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 and SiO2.

[0523] The first bonding layer 4053 bonds the first LED stack 4023 to the support substrate 4051. As shown, the interconnection lines 4029 can be in contact with the first bonding layer 4053. The interconnection lines 4029 are also disposed underneath some regions of the second insulating layer 4028, and the regions of the second insulating layer 4028 that do not have the interconnection lines 4029 can be in contact with the first bonding layer 4053. The first bonding layer 4053 can be light-transmitting or light-opaque. In particular, the contrast of the display device can be improved by using a light-absorbing adhesive layer, such as black epoxy, as the first bonding layer 4053.

[0524] The first bonding layer 4053 can be in direct contact with the support substrate 4051, or, as shown, a hydrophilic material layer 4052 can be disposed at the interface between the support substrate 4051 and the first bonding layer 4053. The hydrophilic material layer 4052 can change the surface of the support substrate 4051 to be hydrophilic, improving the adhesion of the first bonding layer 4053. As used herein, the bonding layer and the hydrophilic material layer are collectively referred to as buffer layers.

[0525] The first bonding layer 4053 has strong adhesive strength to the hydrophilic material layer but weak adhesive strength to the hydrophobic material layer. Therefore, peeling may occur at the portion where the adhesive strength is weak. The hydrophilic material layer 4052 according to the exemplary embodiment can change the hydrophobic surface to a hydrophilic surface, thereby improving the adhesive strength of the first bonding layer 4053 and preventing peeling.

[0526] The hydrophilic material layer 4052 can also be formed by depositing, for example, SiO2 or the like on the surface of the support substrate 4051 and treating the surface of the support substrate 4051 with plasma to modify the surface. The surface-modified layer increases the surface energy and changes the hydrophobic properties to hydrophilic properties. If the second insulating layer 4028 has hydrophobic properties, a hydrophilic material layer can also be disposed on the second insulating layer 4028, and the first bonding layer 4052 can contact the hydrophilic material layer on the second insulating layer 4028.

[0527] The second bonding layer 4055 bonds the second LED stack 4033 to the first LED stack 4023. The second bonding layer 4055 is disposed between the first LED stack 4023 and the first color filter 4037 and is capable of contacting the first color filter 4037. The second bonding layer 4055 is capable of transmitting light generated by the first LED stack 4023. The hydrophilic material layer 4054 is disposed at the interface between the first LED stack 4023 and the second bonding layer 4055. The first conductive type semiconductor layer 4023a of the first LED stack 4023 generally exhibits hydrophobic properties. Therefore, if the second bonding layer 4055 is in direct contact with the first conductive type semiconductor layer 4023a, peeling is likely to occur at the interface between the second bonding layer 4055 and the first conductive type semiconductor layer 4023a.

[0528] The hydrophilic material layer 4054 according to an example embodiment changes the surface of the first LED stack 4023 from having hydrophobic properties to having hydrophilic properties, thereby improving the adhesion of the second bonding layer 4055 and reducing or preventing the occurrence of delamination. The hydrophilic material layer 4054 is formed by depositing SiO or by plasma modifying the surface of the first LED stack 4023 as described above.

[0529] The surface layer of the first color filter 4037 in contact with the second bonding layer 4055 may be a hydrophilic material layer, for example, SiO2. If the surface layer of the first color filter 4037 is not hydrophilic, a hydrophilic material layer is formed on the first color filter 4037, and the second bonding layer 4055 can be in contact with the hydrophilic material layer.

[0530] The third bonding layer 4057 bonds the third LED stack 4043 to the second LED stack 4033. The third bonding layer 4057 is disposed between the second LED stack 4033 and the second color filter 4047 and is capable of contacting the second color filter 4047. The third bonding layer 4057 transmits light generated in the first LED stack 4023 and the second LED stack 4033. A hydrophilic material layer 4056 is disposed at the interface between the second LED stack 4033 and the third bonding layer 4057. The second LED stack 4033 may exhibit hydrophobic properties. As a result, if the third bonding layer 4057 were to directly contact the second LED stack 4033, delamination would likely occur at the interface between the third bonding layer 4057 and the second LED stack 4033.

[0531] The hydrophilic material layer 4056 according to an example embodiment changes the surface of the second LED stack 4033 from hydrophobic to hydrophilic properties, thereby improving the adhesion of the third bonding layer 4057 and preventing delamination from occurring. The hydrophilic material layer 4056 is formed by depositing SiO2 or by plasma modifying the surface of the second LED stack 4033 as described above.

[0532] The surface layer of the second color filter 4047 in contact with the third bonding layer 4057 may be a hydrophilic material layer, for example, SiO2. If the surface layer of the second color filter 4047 is not hydrophilic, a hydrophilic material layer is formed on the second color filter 4047, and the third bonding layer 4057 can be in contact with the hydrophilic material layer.

[0533] The first to third bonding layers 4053, 4055, and 4057 may be formed of light-transmitting SOC, but are not limited thereto, and other transparent organic or inorganic material layers may be used. Examples of organic material layers include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc., and examples of inorganic material layers include Al2O3, SiO2, and SiN xThe organic material layer may be bonded under high vacuum and pressure, and the inorganic material layer may be bonded by, for example, planarizing the surface with a chemical mechanical polishing process, changing the surface energy using plasma or the like, and then using the changed surface energy.

[0534] 73A-73F are schematic cross-sectional views illustrating a method of manufacturing a light emitting diode stack 4000 for a display according to an example embodiment.

[0535] 73A, first, a first LED stack 4023 is grown on a first substrate 4021. The first substrate 4021 may be, for example, a GaAs substrate. The first LED stack 4023 is formed of an AlGaInP-based semiconductor layer and includes a first conductivity type semiconductor layer 4023a, an active layer, and a second conductivity type semiconductor layer 4023b.

[0536] Next, the second conductivity type semiconductor layer 4023b is partially removed to expose the first conductivity type semiconductor layer 4023a. Although Figure 73A shows only one pixel area, the first conductivity type semiconductor layer 4023a is partially exposed for each of the pixel areas.

[0537] The first insulating layer 4027 is formed on the first LED stack 4023 and patterned to form openings. For example, SiO2 is formed on the first LED stack 4023, photoresist is applied, and a photoresist pattern is formed by photolithography and development. Next, the first insulating layer 4027 having openings formed therein is formed by patterning the SiO2 using the photoresist pattern as an etching mask. One of the openings in the first insulating layer 4027 may be located on the first conductivity type semiconductor layer 4023a, and the other opening may be located on the second conductivity type semiconductor layer 4023b.

[0538] Then, the ohmic contact layer 4025a and the ohmic electrode 4026 are formed in the opening of the first insulating layer 4027. The ohmic contact layer 4025a and the ohmic electrode 4026 are formed using a lift-off method. The ohmic contact layer 4025a may be formed first and then the ohmic electrode 4026, or vice versa. Additionally, according to an example embodiment, the ohmic electrode 4026 and the ohmic contact layer 4025a may be formed simultaneously from the same material layer.

[0539] After the ohmic contact layer 4025a is formed, a reflective layer 4025b is formed to cover the ohmic contact layer 4025a and the first insulating layer 4027. The reflective layer 4025b is formed using a lift-off method. The reflective layer 4025b can further cover a portion of the ohmic contact layer 4025a, or can cover substantially the entire ohmic contact layer 4025a as shown. The reflective electrode 4025 is formed by the ohmic contact layer 4025a and the reflective layer 4025b.

[0540] The reflective electrode 4025 can make ohmic contact with the p-type semiconductor layer of the first LED stack 4023, and is therefore hereinafter referred to as the first p-type reflective electrode 4025. The reflective electrode 4025 is spaced apart from the ohmic electrode 4026 and is therefore electrically insulated from the first conductivity type semiconductor layer 4023a.

[0541] A second insulating layer 4028 is formed to cover the reflective electrode 4025 and have an opening that exposes the ohmic electrode 4026. The second insulating layer 4028 is formed of, for example, SiO2 or SOG.

[0542] Thereafter, an interconnection line 4029 is formed on the second insulating layer 4028. The interconnection line 4029 is connected to the ohmic electrode 4026 through the opening in the second insulating layer 4028, and is therefore electrically connected to the first conductivity type semiconductor layer 4023a.

[0543] Although the interconnection line 4029 is shown in FIG. 73A as covering the entire surface of the second insulating layer 4028, the interconnection line 4029 may be partially disposed on the second insulating layer 4028, with the upper surface of the second insulating layer 4028 being exposed around the interconnection line 4029.

[0544] Although the illustrated exemplary embodiment shows one pixel area, the first LED stack 4023 disposed on the substrate 4021 may cover multiple pixel areas, and the interconnection line 4029 may be commonly connected to an ohmic electrode 4026 formed on the multiple areas. Also, multiple interconnection lines 4029 may be formed on the substrate 4021.

[0545] Referring to FIG. 73B , a second LED stack 4033 is grown on a second substrate 4031, and a second-p transparent electrode 4035 and a first color filter 4037 are formed on the second LED stack 4033. The second LED stack 4033 may include a gallium nitride-based first-conductivity-type semiconductor layer 4033a, a second-conductivity-type semiconductor layer 4033b, and an active layer disposed therebetween. The active layer may include a GaInN well layer. The second substrate 4031 is a substrate on which a gallium nitride-based semiconductor layer can be grown and is different from the first substrate 4021. The GaInN composition ratio may be determined so that the second LED stack 4033 can emit green light. The second-p transparent electrode 4035 is in ohmic contact with the second-conductivity-type semiconductor layer 4033b.

[0546] The first color filter 4037 is formed on the second-p transparent electrode 4035, and the details thereof are substantially the same as those described with reference to FIG. 72, so detailed description thereof will be omitted to avoid duplication.

[0547] Referring to FIG. 73C , a third LED stack 4043 is grown on a third substrate 4041, and a third-p transparent electrode 4045 and a second color filter 4047 are formed on the third LED stack 4043. The third LED stack 4043 may include a gallium nitride-based first-conductivity-type semiconductor layer 4043a, a second-conductivity-type semiconductor layer 4043b, and an active layer disposed therebetween. The active layer may include a GaInN well layer. The third substrate 4041 is a substrate on which a gallium nitride-based semiconductor layer can be grown and is different from the first substrate 4021. The GaInN composition ratio may be determined so that the third LED stack 4043 emits blue light. The third-p transparent electrode 4045 is in ohmic contact with the second-conductivity-type semiconductor layer 4043b.

[0548] The second color filter 4047 is substantially the same as that described with reference to FIG. 72, and therefore a detailed description thereof will be omitted to avoid duplication.

[0549] Meanwhile, since the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 are grown on different substrates, the order of their formation is not particularly limited.

[0550] 73D , the first LED stack 4023 is then bonded onto the support substrate 4051 via the first bonding layer 4053. A bonding material layer may be disposed on the support substrate 4051 and the second insulating layer 4028 and bonded to each other to form the first bonding layer 4053. The interconnection line 4029 is disposed toward the support substrate 4051.

[0551] On the other hand, if the surface of the support substrate 4051 has hydrophobic properties, a hydrophilic material layer 4052 is first formed on the support substrate 4051. The hydrophilic material layer 4052 can be further formed by depositing a material layer such as SiO2 on the surface of the support substrate 4051, or by treating the surface of the support substrate 4051 with plasma or the like to increase the surface energy. The surface of the support substrate 4051 is modified by the plasma treatment, and a surface modification layer with high surface energy is formed on the surface of the support substrate 4051. A first bonding layer 4053 can be bonded to the hydrophilic material layer 4052, thereby improving the adhesive strength of the first bonding layer 4053.

[0552] The first substrate 4021 is removed from the first LED stack 4023 using a chemical etching method, thus exposing the first conductivity type semiconductor layer of the first LED stack 4023 on the top surface. The exposed surface of the first conductivity type semiconductor layer 4023a is textured to increase light extraction efficiency, so that a light extraction structure, such as a roughened surface, is formed on the surface of the first conductivity type semiconductor layer 4023a.

[0553] 73E , the second LED stack 4033 is coupled to the first LED stack 4023 via the second bonding layer 4055. The first color filter 4037 is disposed facing the first LED stack 4023 and bonded to the second bonding layer 4055. A bonding material layer is disposed on the first LED stack 4023 and the first color filter 4037 and bonded to each other to form the second bonding layer 4055.

[0554] Alternatively, a hydrophilic material layer 4054 may be formed on the first LED stack 4023 before the second bonding layer 4055 is formed. The hydrophilic material layer 4054 changes the surface of the first LED stack 4023 from hydrophobic to hydrophilic, thereby improving the adhesive strength of the second bonding layer 4055. The hydrophilic material layer 4054 may be formed by depositing a material layer such as SiO2 or by treating the surface of the first LED stack 4023 with plasma or the like to increase the surface energy. The surface of the first LED stack 4023 is modified by the plasma treatment, and a surface-modified layer with high surface energy is formed on the surface of the first LED stack 4023. The second bonding layer 4055 may be bonded to the hydrophilic material layer 4054, thereby improving the adhesive strength of the second bonding layer 4055.

[0555] The second substrate 4031 is separated from the second LED stack 4033 using methods such as laser lift-off or chemical lift-off. In addition, a roughened surface is formed on the exposed surface of the first conductivity type semiconductor layer 4033a using surface texturing to improve light extraction.

[0556] 73F, a hydrophilic material layer 4056 is then formed on the second LED stack 4033. The hydrophilic material layer 4056 changes the surface of the second LED stack 4033 to hydrophilic properties, thereby improving the adhesive strength of the third bonding layer 4057. The hydrophilic material layer 4056 can be further formed by depositing a material layer such as SiO2 or by treating the surface of the second LED stack 4033 with plasma or the like to increase the surface energy. However, if the surface of the second LED stack 4033 has hydrophilic properties, the hydrophilic material layer 4056 can be omitted.

[0557] 72 and 73C, the third LED stack 4043 is coupled to the second LED stack 4033 via the third bonding layer 4057. The second color filter 4047 is disposed facing the second LED stack 4033 and bonded to the third bonding layer 4057. A bonding material layer is disposed on the second LED stack 4033 (or the hydrophilic material layer 4056) and the third color filter 4047 and bonded to each other to form the third bonding layer 4057.

[0558] The third substrate 4041 is separated from the third LED stack 4043 using a technique such as laser lift-off or chemical lift-off. Thus, an LED stack for a display is provided in which the first conductivity type semiconductor layer 4043a of the third LED stack 4043 is exposed, as shown in Fig. 72. In addition, a roughened surface is formed on the exposed surface of the first conductivity type semiconductor layer 4043a by surface texturing.

[0559] The first to third LED stacks 4023, 4033 and 4043 arranged on a support substrate 4051 are patterned pixel by pixel, and the patterned stacks are connected to each other using interconnection lines to provide a display device. A display device according to an exemplary embodiment will now be described.

[0560] FIG. 74 is a schematic circuit diagram of a display device according to an exemplary embodiment, and FIG. 75 is a schematic plan view of a display device according to an exemplary embodiment.

[0561] Referring to Figures 74 and 75, the display device according to the exemplary embodiment can be realized to be driven in a passive matrix manner.

[0562] 72 has a structure in which first to third LED stacks 4023, 4033, and 4043 are stacked vertically, so that one pixel includes three light emitting diodes R, G, and B. Here, the first light emitting diode R may correspond to the first LED stack 4023, the second light emitting diode G may correspond to the second LED stack 4033, and the third light emitting diode B may correspond to the third LED stack 4043.

[0563] In Figures 74 and 75, one pixel includes first to third light-emitting diodes R, G, and B, and each light-emitting diode corresponds to a subpixel. The anodes of the first to third light-emitting diodes R, G, and B are connected to a common line, such as a data line, and the cathodes are connected to other lines, such as scan lines. For example, for a first pixel, the anodes of the first to third light-emitting diodes R, G, and B are commonly connected to the data line Vdata1, and the cathodes are connected to scan lines Vscan1-1, Vscan1-2, and Vscan1-3, respectively. Therefore, the light-emitting diodes R, G, and B in the same pixel can be driven individually.

[0564] In addition, each of the light emitting diodes R, G and B can be driven by utilizing pulse width modulation or by varying the current intensity, allowing the brightness of each sub-pixel to be adjusted.

[0565] 75, a plurality of pixels are formed by patterning the stack described with reference to FIG. 72, and each pixel is connected to a reflective electrode 4025 and interconnection lines 4071, 4073, and 4075. As shown in FIG. 74, the reflective electrode 4025 can be used as a data line Vdata, and the interconnection lines 4071, 4073, and 4075 can be formed as scan lines. Here, the interconnection line 4075 is formed by an interconnection line 4029. The reflective electrode 4025 can electrically connect the first conductive type semiconductor layers 4023a, 4033a, and 4043a of the first to third LED stacks 4023, 4033, and 4043 of the plurality of pixels to each other, and the interconnection line 4029 is disposed substantially perpendicular to the reflective electrode 4025 and can electrically connect the first conductive type semiconductor layers 4023a of the plurality of pixels to each other.

[0566] The pixels are arranged in a matrix, and the anodes of the light-emitting diodes R, G, and B of each pixel are commonly connected to a reflective electrode 4025, and the cathodes are connected to interconnection lines 4071, 4073, and 4075, respectively, which are spaced apart from each other. Here, the interconnection lines 4071, 4073, and 4075 can be used as scan lines Vscan.

[0567] 76 is an enlarged plan view of one pixel of the display device of FIG. 75, FIG. 77 is a schematic cross-sectional view taken along line AA in FIG. 76, and FIG. 78 is a schematic cross-sectional view taken along line BB in FIG.

[0568] Referring again to Figures 75 to 78, in each pixel, a portion of the reflective electrode 4025, a portion of the second-p transparent electrode 4035, a portion of the upper surface of the second LED stack 4033, a portion of the third-p transparent electrode 4045, and the upper surface of the third LED stack 4043 are exposed to the outside.

[0569] The third LED stack 4043 can have a roughened surface 4043r formed on its top surface. The roughened surface 4043r may further be formed on the entire top surface of the third LED stack 4043 or on only a portion of the top surface of the third LED stack 4043.

[0570] A lower insulating layer 4061 may cover the side surfaces of each pixel. The lower insulating layer 4061 may be formed of a light-transmitting material such as SiO2. In this case, the lower insulating layer 4061 may also cover substantially the entire top surface of the third LED stack 4043. Alternatively, according to an exemplary embodiment, the lower insulating layer 4061 may include a light-reflecting or light-absorbing layer to prevent light from traveling laterally from the first to third LED stacks 4023, 4033, and 4043. In this case, the lower insulating layer 4061 at least partially exposes the top surface of the third LED stack 4043. The lower insulating layer 4061 may include, for example, a distributed Bragg reflector or a metallic reflective layer, or an organic reflective layer on a transparent insulating layer, and may also include a light-absorbing layer such as black epoxy. The light-absorbing layer such as black epoxy may prevent light from radiating outside the pixel, thereby improving the contrast ratio between pixels in the display device.

[0571] The lower insulating layer 4061 may have an opening 4061a exposing the top surface of the third LED stack 4043, an opening 4061b exposing the top surface of the second LED stack 4033, an opening 4061c exposing the third-p transparent electrode 4045, an opening 4061d exposing the second-p transparent electrode 4035, and an opening 4061e exposing the first p-type reflective electrode 4025. The top surface of the first LED stack 4023 does not need to be exposed to the outside.

[0572] The interconnection line 4071 and the interconnection line 4073 are formed on the support substrate 4051 near the first to third LED stacks 4023, 4033, and 4043, and are disposed on the lower insulating layer 4061 to be insulated from the first p-type reflective electrode 4025. The connector 4077ab connects the second p-type transparent electrode 4035 and the third p-type transparent electrode 4045 to the reflective electrode 4025. Therefore, the anodes of the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 are commonly connected to the reflective electrode 4025.

[0573] The interconnection line 4075 or 4029 may be disposed below the reflective electrode 4025 an...

Claims

1. A light emitting device comprising: a circuit board; and a light emitting device electrically connected to the circuit board, the light emitting device comprises: A support substrate; a first LED, a second LED, and a third LED disposed on the support substrate; an insulating layer covering the first LED, the second LED, and the third LED; a first interconnection line disposed on the support substrate and electrically connected to the first LED; a second interconnection line disposed on the support substrate and electrically connected to the second LED; a third interconnection line disposed on the support substrate and electrically connected to the third LED; the third interconnection line is covered by the support substrate; the third interconnection line includes a third connection portion extending from the third interconnection line toward the third LED, the third connection portion vertically overlapping the third LED, the third interconnection line is disposed between the third LED and a periphery of the support substrate; The insulating layer further covers the first interconnection line and the second interconnection line.

2. The light emitting device according to claim 1 , wherein the first interconnection line is disposed inside a periphery of the support substrate.

3. The light emitting device of claim 2 , wherein the first interconnection line is spaced apart from the third interconnection line.

4. The light emitting device according to claim 3 , wherein the third interconnection line is disposed inside the periphery of the support substrate.

5. The light emitting device of claim 4 , wherein the second interconnection line is spaced apart from the third interconnection line.

6. A light-emitting device as described in claim 5, wherein a portion of the upper surface of the support substrate is exposed.

7. The light-emitting device described in claim 1, wherein the light-emitting device includes a reflective electrode electrically connected to the third LED, and the reflective electrode is arranged between the third LED and the supporting substrate.

8. The light emitting device of claim 1 , wherein the third LED has a rectangular or square shape.

9. A light-emitting device as described in claim 1, wherein the first LED includes a third transparent electrode electrically connected to the first LED, and the third transparent electrode is arranged between the first LED and the supporting substrate.

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