Display device and unit pixel

Abstract

A display device and a unit pixel. The display device includes: a TFT substrate having an electrode pad thereon; a first LED stack located on the TFT substrate; a second LED stack located on the first LED stack; a third LED stack located on the second LED stack; and a connector electrically connecting the first LED stack to the third LED stack to the electrode pad of the TFT substrate, wherein the first LED stack, the second LED stack, and the third LED stack can be driven independently, light generated from the first LED stack is emitted to the outside through the second LED stack and the third LED stack, and light generated from the second LED stack is emitted to the outside through the third LED stack.

Description

[0001] This application is a divisional application of the invention patent application with the application date of November 27, 2018, application number 201880044973.1, and invention name “LED unit for display and display device having the LED unit”. Technical Field

[0002] Exemplary embodiments of the invention generally relate to a display device, and more particularly, to a display device having light emitting diode (LED) unit pixels, a light emitting device for a display and a display device, and to a light emitting device for a display having a stacked structure of multiple LEDs and a display device having the light emitting device. Background Art

[0003] Light-emitting diodes (LEDs) have been used as inorganic light sources in various fields such as display devices, automotive lighting, and general lighting. Due to their advantages of long life, low power consumption, and high response speed, LEDs have rapidly replaced traditional light sources.

[0004] Meanwhile, prior art light emitting diodes have been primarily used as backlight sources in display devices. However, micro LED displays have recently been developed as next-generation displays that directly implement images using light emitting diodes.

[0005] Typically, a display device uses a mixture of blue, green, and red to create a variety of colors. A display device includes multiple pixels to create images with various colors, and each pixel includes sub-pixels of blue, green, and red. The color of a particular pixel is determined by the colors of the sub-pixels, and the image is created by combining these pixels.

[0006] In the case of a micro-LED display, the micro-LEDs corresponding to each sub-pixel are arranged on a two-dimensional plane. Therefore, a large number of micro-LEDs need to be arranged on a single substrate. However, micro-LEDs have a very small size, with a surface area of ​​10,000 square μm or less, and therefore, various problems arise due to this small size. Specifically, it is difficult to process light-emitting diodes having a small size, and it is not easy to mount light-emitting diodes (especially more than hundreds of thousands or millions of light-emitting diodes) on a display panel, and it is not easy to replace defective LEDs in the mounted micro-LEDs with good LEDs.

[0007] In addition, since the sub-pixels are arranged on a two-dimensional plane, the area occupied by a pixel including blue, green, and red sub-pixels is relatively large. Therefore, in order to arrange the sub-pixels in a limited area, the area of ​​each sub-pixel needs to be reduced, resulting in a decrease in brightness due to the reduction in the light-emitting area.

[0008] The above information disclosed in this Background section is only for understanding the background of the inventive concept and therefore it may contain information that does not constitute the prior art. Summary of the Invention

[0009] Technical issues

[0010] A light emitting diode and a display using the same constructed according to the principles of the invention and some exemplary embodiments can increase the light emitting area of ​​each sub-pixel without increasing the pixel area.

[0011] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (e.g., micro-LEDs) provide high reliability due to a stable LED structure and a simplified manufacturing process, where a single via can be connected to one or more semiconductor layers of each LED stack.

[0012] Light emitting diodes and displays using the same (eg, micro-LEDs) constructed according to inventive principles and some exemplary embodiments provide pixels that can be manufactured simultaneously, eliminating the cumbersome process of individually mounting pixels.

[0013] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (eg, micro-LEDs) can be driven in an active matrix manner.

[0014] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (eg, micro-LEDs) can shorten mounting process time.

[0015] Light-emitting diodes and displays using the same (e.g., micro-LEDs) constructed according to the principles of the present invention and some exemplary embodiments can prevent light interference between LED stacks by stacking a first LED stack, a second LED stack, and a third LED stack to emit light of decreasing wavelengths. For example, the first LED stack, the second LED stack, and the third LED stack can emit red light, green light, and blue light, respectively.

[0016] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (e.g., micro-LEDs) are capable of suppressing the generation of secondary light between LED stacks without arranging color filters between the LED stacks, which are typically formed between the LED stacks to prevent the generation of secondary light by light emitted from adjacent LED stacks.

[0017] Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts.

[0018] Technical Solution

[0019] A display device according to an exemplary embodiment includes: a thin film transistor (TFT) substrate; a first LED subunit disposed on the TFT substrate; a second LED subunit disposed on the first LED subunit; a third LED subunit disposed on the second LED subunit; electrode pads (also referred to as "electrode pads") disposed between the TFT substrate and the first LED subunit; and a connector connecting the first LED subunit, the second LED subunit, and the third LED subunit to a corresponding one of the electrode pads, wherein the first LED subunit, the second LED subunit, and the third LED subunit are configured to be independently driven, light generated from the first LED subunit is configured to be emitted to the outside of 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 to the outside of the display device by passing through the third LED subunit.

[0020] The first, second, and third LED subunits may include first, second, and third LED stacks, respectively, and the first, second, and third LED stacks may be configured to emit red, green, and blue light, respectively.

[0021] The display device may include a first reflective electrode disposed between the TFT substrate and the first LED subunit and contacting a lower surface of the first LED subunit, wherein the connector may include a first lower connector connecting the first reflective electrode to a first connection pad among the electrode pads.

[0022] The connector may further include a first upper connector connecting an upper surface of the first LED sub-unit to a second electrode pad among the electrode pads.

[0023] The display device may further include: a second transparent electrode, inserted between the first LED sub-unit and the second LED sub-unit and in ohmic contact with the lower surface of the second LED sub-unit; and a third transparent electrode, inserted between the second LED sub-unit and the third LED sub-unit and in ohmic contact with the lower surface of the third LED sub-unit, wherein the connector may further include a second lower connector connecting the second transparent electrode to a first electrode pad among the electrode pads, a second upper connector connecting the upper surface of the second LED sub-unit 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 the upper surface of the third LED sub-unit to a fourth electrode pad among the electrode pads.

[0024] The first lower connection may be connected to an upper surface of the first reflective electrode, the second lower connection may be connected to an upper surface of the second transparent electrode, and the third lower connection may be connected to an upper surface of the third transparent electrode.

[0025] The first upper connector may be connected to the upper surface of the first LED subunit, the second upper connector may be connected to the upper surface of the second LED subunit, the third upper connector may be connected to the upper surface of the third LED subunit, and at least one upper connector may be substantially annular in shape.

[0026] The connector may further include an intermediate connector connecting the second upper connector and the third upper connector to a third electrode pad and a fourth electrode pad of the electrode pads, respectively.

[0027] Each connecting member may pass through at least one of the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit.

[0028] The first, second, and third lower connectors may be connected to first ones of the electrode pads, and the first, second, and third upper connectors may be connected to different ones of the electrode pads, respectively.

[0029] The first, second, and third lower connectors may be stacked on each other in a vertical direction, and the first, second, and third upper connectors may be spaced apart from each other in the vertical and lateral directions.

[0030] The display device may further include: a second transparent electrode, inserted between the first LED sub-unit and the second LED sub-unit and in ohmic contact with the lower surface of the second LED sub-unit; and a third transparent electrode, inserted between the second LED sub-unit and the third LED sub-unit and in ohmic contact with the lower surface of the third LED sub-unit, wherein the connector may further include a second lower connector connecting the second transparent electrode to the third electrode pad among the electrode pads, a second upper connector connecting the upper surface of the second LED sub-unit to the second electrode pad among the electrode pads, a third lower connector connecting the third transparent electrode to the fourth electrode pad among the electrode pads, and a third upper connector connecting the upper surface of the third LED sub-unit to the second electrode pad among the electrode pads, the first lower connector, the second lower connector and the third lower connector may be separated from each other and respectively connected to the first electrode pad, the third electrode pad and the fourth electrode pad among the electrode pads, and the first upper connector, the second upper connector and the third upper connector may be electrically connected to the second electrode pad among the electrode pads.

[0031] The first, second, and third lower connectors may be spaced apart from each other in the vertical and lateral directions, and the first, second, and third upper connectors may be stacked in the vertical direction.

[0032] The display device may further include: a first color filter, inserted between the first LED sub-unit and the second LED sub-unit, and configured to transmit light generated from the first LED sub-unit and reflect light generated from the second LED sub-unit; and a second color filter, inserted between the second LED sub-unit and the third LED sub-unit, and configured to transmit light generated from the first LED sub-unit and the second LED sub-unit and reflect light generated from the third LED sub-unit.

[0033] The display device may also include: a first bonding layer inserted between the TFT substrate and the first LED sub-unit; a second bonding layer inserted between the first LED sub-unit and the second LED sub-unit; and a third bonding layer inserted between the second LED sub-unit and the third LED sub-unit, wherein the second bonding layer is constructed to transmit light generated from the first LED sub-unit, and the third bonding layer is constructed to transmit light generated from the first LED sub-unit and the second LED sub-unit.

[0034] The display device may be configured to be driven in an active matrix manner.

[0035] In a plan view, the third lower connection members and the third upper connection members may be exposed by the third LED sub-unit.

[0036] The first reflective electrode may be disposed between the first LED sub-unit and the electrode pad.

[0037] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include micro-LEDs having a surface area of ​​less than about 10,000 μm 2 .

[0038] The first LED sub-unit may be configured to emit one of red, green, and blue light, the second LED sub-unit may be configured to emit one of red, green, and blue light that is different from that emitted by the first LED sub-unit, and the third LED sub-unit may be configured to emit one of red, green, and blue light that is different from that emitted by the first and second LED sub-units.

[0039] According to an exemplary embodiment, a light emitting device includes: a first LED sub-unit; a second LED sub-unit disposed adjacent to the first LED sub-unit; a third LED sub-unit disposed adjacent to the second LED sub-unit; and electrode pads disposed on the first LED sub-unit and electrically connected to the first, second, and third LED sub-units, the electrode pads including a common electrode pad electrically connected to each of the first, second, and third LED sub-units and a first electrode pad, a second electrode pad, and a third electrode pad connected to a corresponding one of the first, second, and third LED sub-units, wherein the common electrode pad, the second electrode pad, and the third electrode pad are electrically connected to the second and third LED sub-units through a hole passing through the first LED sub-unit, the first, second, and third LED sub-units are configured to be independently driven, light generated in the first LED sub-unit is configured to be emitted to the outside of the light emitting device through the second and third LED sub-units, and light generated in the second LED sub-unit is configured to be emitted to the outside of the light emitting device through the third LED sub-unit.

[0040] The first, second, and third LED subunits may include first, second, and third LED stacks, respectively, and the first, second, and third LED stacks may be configured to emit red, green, and blue light, respectively.

[0041] The light emitting device may further include: a first reflective electrode disposed between the electrode pad and the first LED sub-unit and ohmically connected to the first LED sub-unit, wherein the common electrode pad is connected to the first reflective electrode.

[0042] The first reflective electrode may include: an ohmic contact layer in ohmic contact with an upper surface of the first LED sub-unit; and a reflective layer covering the ohmic contact layer.

[0043] The first reflective electrode may have a hollow portion defined by a substantially ring-shaped member, and the common electrode pad may pass through the hollow portion of the substantially ring-shaped member.

[0044] The light-emitting device may further include: a second transparent electrode interposed between the second LED sub-unit and the third LED sub-unit and in ohmic contact with the lower surface of the second LED sub-unit; and a third transparent electrode in ohmic contact with the upper surface of the third LED sub-unit, wherein the common electrode pad may be electrically connected to the second transparent electrode and the third transparent electrode.

[0045] The common electrode pad may be connected to an upper surface of the second transparent electrode and an upper surface of the third transparent electrode.

[0046] Each of the first LED sub-unit and the third LED sub-unit may include a first conductive semiconductor layer and a second conductive semiconductor layer arranged on a partial area of ​​the first conductive semiconductor layer, and the first electrode pad and the third electrode pad may be electrically connected to the first conductive semiconductor layer of the first LED sub-unit and the third LED sub-unit, respectively.

[0047] The light emitting device may further include: a first ohmic electrode disposed on the first conductive semiconductor layer of the first LED sub-unit, wherein the first electrode pad is connected to the first ohmic electrode.

[0048] The third electrode pad may be directly connected to the first conductive type semiconductor layer of the third LED sub-unit.

[0049] The light emitting device may further include: a first color filter disposed between the third transparent electrode and the second LED sub-unit; and a second color filter disposed between the first LED sub-unit and the second LED sub-unit.

[0050] The first and second color filters may include insulating layers having different refractive indices.

[0051] The common electrode pad and the third electrode pad may be electrically connected to the third LED sub-unit through a hole passing through the second LED sub-unit.

[0052] The light emitting device may further include: a substrate on which the third LED sub-unit is disposed.

[0053] The substrate may include a sapphire substrate or a gallium nitride substrate.

[0054] The light emitting device may further include an insulating layer disposed between the first LED sub-unit and the electrode pad, wherein the electrode pad is electrically connected to the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit through the insulating layer.

[0055] The insulating layer may include at least one of a distributed Bragg reflector and a light blocking material.

[0056] A display apparatus 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 may include the light emitting device according to the exemplary embodiment, wherein the electrode pad may be electrically connected to the circuit board.

[0057] Each of the light emitting devices may include a substrate coupled to the third LED sub-unit, and the substrates of the light emitting devices may be spaced apart from each other.

[0058] According to an exemplary embodiment, a light emitting device includes: a substrate; a first LED sub-unit disposed on the substrate; a second LED sub-unit disposed on the first LED sub-unit; a third LED sub-unit disposed on the second LED sub-unit; and electrode pads electrically connected to the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit, the electrode pads including a common electrode pad electrically connected to each of the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit through a single path, and a first electrode pad, a second electrode pad, and a third electrode pad connected to a corresponding one of the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit.

[0059] The electrode pad may be disposed between the substrate and the first LED subunit, the via may include a plurality of connectors connected to each of the first, second, and third LED subunits, and the connectors may include a first portion having a width greater than a width of the via.

[0060] The first LED sub-unit may include a reflective electrode disposed on a lower surface of the first LED sub-unit, and the reflective electrode may contact the first portion of the corresponding connector.

[0061] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may be disposed between the electrode pad and the substrate, and the via may have a width that narrows in a direction from the electrode pad to the substrate.

[0062] The third LED sub-unit may include a reflective electrode disposed on an upper surface of the third LED sub-unit, and the common electrode pad may directly contact the reflective electrode.

[0063] 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.

[0064] Beneficial effects

[0065] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same can increase the light emitting area of ​​each pixel without increasing the pixel area.

[0066] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (e.g., micro-LEDs) provide high reliability due to a single via that can connect to one or more semiconductor layers of each LED stack, a stable LED structure, and a simplified manufacturing process.

[0067] Light emitting diodes and displays using the same (eg, micro-LEDs) constructed according to inventive principles and some exemplary embodiments provide pixels that can be manufactured simultaneously, thereby eliminating the cumbersome process of individually mounting pixels.

[0068] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (eg, micro-LEDs) can be driven in an active matrix manner.

[0069] Light emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (eg, micro-LEDs) can shorten mounting process time.

[0070] Light-emitting diodes and displays using the same (e.g., micro-LEDs) constructed according to the principles of the present invention and some exemplary embodiments can prevent light interference between LED stacks by stacking a first LED stack, a second LED stack, and a third LED stack to emit light of decreasing wavelengths. For example, the first LED stack, the second LED stack, and the third LED stack can emit red light, green light, and blue light, respectively.

[0071] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same (e.g., micro-LEDs) are capable of suppressing the generation of secondary light between LED stacks without arranging color filters between the LED stacks, which are typically formed between LED stacks to prevent the generation of secondary light due to light emitted from adjacent LED stacks. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The accompanying drawings illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept. wherein, the accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0073] Figure 1 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0074] Figure 2 It is along Figure 1 A schematic cross-sectional view taken along line AA of FIG.

[0075] Figure 3A 、 Figure 3B 、 Figure 4A 、 Figure 4B 、 Figure 5A 、 Figure 5B 、 Figure 6A 、 Figure 6B 、 Figure 7A 、 Figure 7B 、 Figure 8A 、 Figure 8B 、 Figure 9A 、 Figure 9B 、 Figure 10A 、 Figure 10B 、 Figure 11A 、 Figure 11B 、 Figure 12A 、 Figure 12B 、 Figure 13A 、 Figure 13B 、 Figure 14A 、 Figure 14B 、 Figure 15A 、 Figure 15B 、 Figure 16A and Figure 16B are schematic plan views and schematic cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0076] Figure 17 is a schematic plan view of a display device according to another exemplary embodiment.

[0077] Figure 18 It is along Figure 17 A schematic cross-sectional view taken along line BB of FIG.

[0078] Figure 19 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0079] Figure 20 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0080] Figure 21A is a schematic plan view of a light emitting device according to an exemplary embodiment.

[0081] Figure 21B It is along Figure 21A A schematic cross-sectional view taken along line AA of FIG.

[0082] Figure 22 、 Figure 23 、 Figure 24 、 Figure 25 、 Figure 26A 、 Figure 26B 、 Figure 27A 、 Figure 27B 、 Figure 28A 、 Figure 28B 、 Figure 29 、 Figure 30A、 Figure 30B 、 Figure 31A 、 Figure 31B 、 Figure 32A 、 Figure 32B 、 Figure 33A 、 Figure 33B 、 Figure 34A 、 Figure 34B 、 Figure 35A and Figure 35B are schematic plan views and cross-sectional views illustrating a method of manufacturing a light emitting device according to an exemplary embodiment.

[0083] Figure 36 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0084] Figure 37A 、 Figure 37B 、 Figure 37C 、 Figure 37D and Figure 37E is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0085] Figure 38 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0086] Figure 39 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0087] Figure 40 yes Figure 39 An enlarged plan view of a pixel of a display device.

[0088] Figure 41 It is along Figure 40 A schematic cross-sectional view taken along line AA of FIG.

[0089] Figure 42 It is along Figure 40 A schematic cross-sectional view taken along line BB of FIG.

[0090] Figure 43A 、 Figure 43B 、 Figure 43C 、 Figure 43D 、 Figure 43E 、 Figure 43F 、 Figure 43G 、 Figure 43H 、 Figure 43I 、 Figure 43J and Figure 43K is a schematic plan view illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0091] Figure 44 is a schematic circuit diagram of a display device according to another exemplary embodiment.

[0092] Figure 45 is a schematic plan view of a pixel of a display device according to another exemplary embodiment.

[0093] Figure 46 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0094] Figure 47A 、 Figure 47B 、 Figure 47C 、 Figure 47D and Figure 47E is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0095] Figure 48 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0096] Figure 49 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0097] Figure 50 yes Figure 49 An enlarged plan view of a pixel of a display device.

[0098] Figure 51 It is along Figure 50 A schematic cross-sectional view taken along line AA of FIG.

[0099] Figure 52 It is along Figure 50 A schematic cross-sectional view taken along line BB of FIG.

[0100] Figure 53A 、 Figure 53B 、 Figure 53C 、 Figure 53D 、 Figure 53E 、 Figure 53F 、 Figure 53G 、 Figure 53H 、 Figure 53I 、 Figure 53J and Figure 53K is a schematic plan view illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0101] Figure 54 is a schematic circuit diagram of a display device according to another exemplary embodiment.

[0102] Figure 55 is a schematic plan view of a pixel of a display device according to another exemplary embodiment.

[0103] Figure 56 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0104] Figure 57 is a schematic cross-sectional view of a light emitting diode pixel for a display device according to an exemplary embodiment.

[0105] Figure 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0106] Figure 59A and Figure 59B are top and bottom views of one pixel of a display device according to an exemplary embodiment.

[0107] Figure 60A It is along Figure 59A A schematic cross-sectional view taken along line AA of FIG.

[0108] Figure 60B It is along Figure 59A A schematic cross-sectional view taken along line BB of FIG.

[0109] Figure 60C It is along Figure 59A A schematic cross-sectional view taken along line CC of FIG.

[0110] Figure 60D It is along Figure 59A Schematic cross-sectional view taken along line DD.

[0111] Figure 61A 、 Figure 61B 、 Figure 62A 、 Figure 62B 、 Figure 63A 、 Figure 63B 、 Figure 64A 、 Figure 64B 、 Figure 65A 、 Figure 65B 、 Figure 66A 、 Figure 66B 、 Figure 67A 、 Figure 67B 、 Figure 68A and Figure 68B are schematic plan views and schematic cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0112] Figure 69 is a schematic cross-sectional view of a light emitting diode pixel for a display device according to another exemplary embodiment.

[0113] Figure 70 is an enlarged top view of one pixel of a display device according to an exemplary embodiment.

[0114] Figure 71A and Figure 71B Along Figure 70 A cross-sectional view taken along lines GG and HH in FIG.

[0115] Figure 72 is a schematic cross-sectional view of a light emitting diode (LED) stack for a display according to an exemplary embodiment.

[0116] Figure 73A 、 Figure 73B 、 Figure 73C 、 Figure 73D 、 Figure 73E and Figure 73F is a schematic cross-sectional view illustrating a method for manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0117] Figure 74 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0118] Figure 75 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0119] Figure 76 yes Figure 75 An enlarged plan view of a pixel of a display device.

[0120] Figure 77 It is along Figure 76 A schematic cross-sectional view taken along line AA of FIG.

[0121] Figure 78 It is along Figure 76 A schematic cross-sectional view taken along line BB of FIG.

[0122] Figure 79A 、 Figure 79B 、 Figure 79C 、 Figure 79D 、 Figure 79E 、 Figure 79F 、 Figure 79G and Figure 79H is a schematic plan view illustrating a method for manufacturing a display device according to an exemplary embodiment.

[0123] Figure 80 is a schematic cross-sectional view of a light emitting stack structure according to an exemplary embodiment.

[0124] Figure 81A and Figure 81B is a cross-sectional view of a light emitting stack structure according to an exemplary embodiment.

[0125] Figure 82 is a cross-sectional view of a light emitting stack structure including a wiring part according to an exemplary embodiment.

[0126] Figure 83 is a cross-sectional view of a light emitting stack structure according to an exemplary embodiment.

[0127] Figure 84 is a plan view of a display device according to an exemplary embodiment.

[0128] Figure 85 yes Figure 84 An enlarged plan view of portion P1.

[0129] Figure 86 is a structural diagram of a display device according to an exemplary embodiment.

[0130] Figure 87 This is a circuit diagram of one pixel in a passive display device.

[0131] Figure 88 This is a circuit diagram of one pixel in an active-type display device.

[0132] Figure 89 is a plan view of a pixel according to an exemplary embodiment.

[0133] Figure 90A and Figure 90B Along Figure 89 Cross-sectional views taken along line II' and line II-II'.

[0134] Figure 91A 、 Figure 91B and Figure 91C It is along Figure 89 1 is a cross-sectional view taken along line II′ of FIG. 1 , illustrating a process of stacking first to third epitaxial stacks on a substrate according to an exemplary embodiment.

[0135] Figure 92 、 Figure 94 、 Figure 96 、 Figure 98 、 Figure 100 、 Figure 102 and Figure 104 are plan views sequentially illustrating a method of manufacturing pixels on a substrate.

[0136] Figure 93A 、 Figure 95A 、 Figure 97A and Figure 97C 、 Figure 99A 、 Figure 101A 、 Figure 103A and Figure 103C 、 Figure 105A Along Figure 92 、 Figure 94 、 Figure 96 、 Figure 98 、 Figure 100 、 Figure 102 、 Figure 104 A cross-sectional view taken along line II'.

[0137] Figure 93B、 Figure 95B 、 Figure 97B and Figure 97D 、 Figure 99B 、 Figure 101B 、 Figure 103B and Figure 103D 、 Figure 105B Along Figure 92 、 Figure 94 、 Figure 96 、 Figure 98 、 Figure 100 、 Figure 102 、 Figure 104 A sectional view taken along line II-II'.

[0138] Figure 106 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0139] Figure 107A yes Figure 106 A cross-sectional view of a display device.

[0140] Figure 107B is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0141] Figure 108A 、 Figure 108B 、 Figure 108C 、 Figure 108D 、 Figure 108E 、 Figure 109A 、 Figure 109B 、 Figure 109C 、 Figure 109D 、 Figure 109E 、 Figure 110A 、 Figure 110B 、 Figure 110C 、 Figure 110D 、 Figure 111A 、 Figure 111B 、 Figure 111C 、 Figure 111D 、 Figure 112A 、 Figure 112B 、 Figure 112C 、 Figure 112D 、 Figure 113A 、 Figure 113B and Figure 114 are schematic plan views and cross-sectional views illustrating a method of manufacturing a display apparatus according to an exemplary embodiment.

[0142] Figure 115A 、 Figure 115B and Figure 115C is a schematic cross-sectional view of a metal bonding material according to an exemplary embodiment. DETAILED DESCRIPTION

[0143] In the following description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of the various exemplary embodiments or implementations of the invention. As used herein, "embodiment" and "implementation" are interchangeable words as non-limiting examples of devices or methods employing one or more inventive concepts disclosed herein. However, it is apparent that the various exemplary embodiments can be implemented without these specific details or in the case of one or more equivalent arrangements. In other cases, in order to avoid making the various exemplary embodiments unnecessarily vague, known structures and devices are shown in block diagram form. In addition, the various exemplary embodiments may be different, but do not have to be exclusive. For example, without departing from the inventive concept, the specific shape, construction and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment.

[0144] Unless otherwise indicated, the exemplary embodiments shown will be understood as providing exemplary features of different details of some ways in which the inventive concept can be implemented in practice. Therefore, unless otherwise indicated, the features, components, modules, layers, films, panels, regions and / or aspects, etc. (hereinafter, individually or collectively referred to as "elements / factors") of the various embodiments may be further combined, separated, interchanged and / or rearranged without departing from the inventive concept.

[0145] The use of cross hatching and / or shading is generally provided in the accompanying drawings to make the boundaries between adjacent elements clear. Thus, unless otherwise specified, the presence and absence of cross hatching or shading do not express or indicate any preference or requirement for the specific material, material properties, size, ratio, commonality between the elements shown and / or any other characteristics, attributes, properties, etc. of the elements. In addition, in the accompanying drawings, the size and relative size of the elements can be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, a specific process sequence can be performed in a different order than described. For example, two processes described in succession can be performed substantially simultaneously or in an order opposite to the described order. In addition, the same reference numerals represent the same elements.

[0146] When an element, such as a layer, is referred to as being "on," "connected to," or "bound to" another element or layer, the element may be directly on, directly connected to, or directly bound to the other element or layer, or there may be intermediate elements or layers. However, when an element or layer is referred to as being "directly on," "directly connected to," or "directly bound to" another element or layer, there are no intermediate elements or layers. For this purpose, the term "connected" may refer to a physical connection, an electrical connection, and / or a fluid connection with or without an intermediate element. In addition, the D1 axis, the D2 axis, and the D3 axis are not limited to the three axes of a rectangular coordinate system (such as the x-axis, the y-axis, and the z-axis), and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis, and the D3 axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be interpreted as X only, Y only, Z only, 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.

[0147] Although the terms "first," "second," etc. may be used herein 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. Thus, the first element discussed below could be named the second element without departing from the teachings of the disclosure.

[0148] For descriptive purposes, spatially relative terms such as "under," "beneath," "under," "down," "over," "up," "above," "higher," "side" (e.g., as in "sidewall"), etc., may be used herein to describe the relationship of one element to another (other) element as shown in the accompanying drawings. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the drawings is turned over, an element described as "under" or "beneath" other elements or features would then be positioned "over" the other elements or features. Thus, the exemplary term "under" can include both above and below orientations. Furthermore, the device can be positioned otherwise (e.g., rotated 90 degrees or at other orientations), and as such, the spatially relative descriptors used herein should be interpreted accordingly.

[0149] The terms used herein are for the purpose of describing specific embodiments and are not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms "one", "one (kind / person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, the description indicates the presence of stated features, integral bodies, steps, operations, elements, components and / or their groups, but do not exclude the presence or addition of one or more other features, integral bodies, steps, operations, elements, components and / or their groups. It should also be noted that, as used herein, the terms "substantially (substantially)", "approximately (about)" and other similar terms are used as approximate terms rather than as terms of degree, so that they are used to explain the inherent deviations of measured values, calculated values ​​and / or provided values ​​that will be recognized by those of ordinary skill in the art.

[0150] Various exemplary embodiments are described herein with reference to cross-sectional views and / or exploded views that are schematic diagrams of idealized exemplary embodiments and / or intermediate structures. As such, variations in the shapes of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. Therefore, the exemplary embodiments disclosed herein should not be necessarily construed as limited to the specific illustrated shapes of the regions, but rather are to include deviations in shape due to, for example, manufacturing. In this manner, the regions illustrated in the accompanying drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of the regions of the device and, as such, are not necessarily intended to be limiting.

[0151] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Unless expressly defined as such herein, terms (such as those defined in common dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an ideal or overly formal sense.

[0152] As used herein, a light emitting device or light emitting diode according to an exemplary embodiment may include a micro-LED having a surface area of ​​less than about 10,000 square μm as known in the art. In other exemplary embodiments, the micro-LED may have a surface area of ​​less than about 4,000 square μm or less than about 2,500 square μm, depending on the specific application.

[0153] Figure 1 is a schematic plan view of a display apparatus according to an exemplary embodiment. Figure 2 It is along Figure 1 A schematic cross-sectional view taken along line AA of FIG.

[0154] Reference Figure 1 and Figure 2 , the display device may include a substrate 51, electrode pads (also referred to as "electrode pads") 53a, 53b, 53c, and 53d, 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 59a, 59b, 59c, 59d, 69b, 69c, 69d, 79c, and 79d, and insulating layers 57, 67, and 77. As used herein, a connector may be any type of structure including a through hole, a via, a wiring, a line, a conductive material, etc., for electrically and / or mechanically connecting two elements such as layers.

[0155] Substrate 51 supports LED stacks 23, 33, and 43. Furthermore, substrate 51 may have internal circuitry. For example, substrate 51 may be a silicon substrate having thin film transistors formed therein. TFT substrates have been widely used in display applications such as LCD displays for driving display devices in an active matrix manner. Because TFT substrates are well known in the art, a detailed description of their structure will be omitted.

[0156] although Figure 1 and Figure 2 One unit pixel provided on the substrate 51 is shown, but a plurality of unit pixels may be arranged on the substrate 51 and may be driven in an active matrix manner.

[0157] Electrode pads 53a, 53b, 53c, and 53d are exposed on the substrate 51. Each of the electrode pads 53a, 53b, 53c, and 53d is connected to one of the sub-pixels of the unit pixel disposed on the substrate 51, but the electrode pad 53d is connected to each of the three sub-pixels. Each of the electrode pads 53a, 53b, 53c, and 53d can be connected to an internal circuit of the substrate 51.

[0158] Each of the first LED stack 23 , the second LED stack 33 , and the third LED stack 43 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed (placed) between the n-type semiconductor layer and the p-type semiconductor layer. The active layer may have a multi-quantum well structure.

[0159] The closer to the substrate 51, the longer wavelength light can be emitted from the LED stack. For example, the first LED stack 23 can be an inorganic light emitting diode configured to emit red light, the second LED stack 33 can be an inorganic light emitting diode configured to emit green light, and the third LED stack 43 can be an inorganic light emitting diode configured to emit blue light. The first LED stack 23 can include a GaInP base well layer, and the second LED stack 33 and the third LED stack 43 can include a GaInN base well layer. However, the inventive concept is not limited thereto, and when the pixel includes a micro-LED, the first LED stack 23 can emit any one of red, green, and blue light, and the second LED stack 33 and the third LED stack 43 can emit a different one of red, green, and blue light without adversely affecting operation due to the small form factor of the micro-LED.

[0160] The surfaces of each of the LED stacks 23, 33, and 43 may be an n-type semiconductor layer and a p-type semiconductor layer, respectively. Hereinafter, the upper and lower surfaces of each of the first to third LED stacks 23, 33, and 43 may be described as n-type and p-type, respectively. However, the inventive concept is not limited thereto, and the types of the upper and lower surfaces of each LED stack may be reversed or variously modified.

[0161] When the upper surface of the third LED stack 43 is n-type, the upper surface of the third LED stack 43 can be surface-textured by chemical etching or the like to form a rough surface (also referred to as a roughened surface). The upper surfaces of the first LED stack 23 and the second LED stack 33 may also be subjected to surface texturing. However, when the second LED stack 33 emits green light, because green light has a higher visibility than red and blue light, the luminous efficiency of the first LED stack 23 and the third LED stack 43 may be preferably improved to a greater extent than the luminous efficiency of the second LED stack 33. In this way, without surface texturing the second LED stack 33, the first LED stack 23 and the third LED stack 43 may be surface-textured to improve light extraction efficiency. In this way, the light intensities of red, green, and blue light can be balanced and adjusted to have substantially similar levels.

[0162] The first LED stack 23 may be disposed close to the support base 51, the second LED stack 33 may be disposed on the first LED stack 23, and the third LED stack 43 may be disposed on the second LED stack 33. Because the first LED stack 23 can emit light having a longer wavelength than the second LED stack 33 and the third LED stack 43, the light generated from the first LED stack 23 may be transmitted through the second LED stack 33 and the third LED stack 43 and may be emitted to the outside. Furthermore, because the second LED stack 33 can emit light having a longer wavelength than the third LED stack 43, the light generated from the second LED stack 33 may be transmitted through the third LED stack 43 and may be emitted to the outside.

[0163] The first reflective electrode 25 makes 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.

[0164] The ohmic contact layer 25a is partially in contact with the p-type semiconductor layer. In order to prevent the ohmic contact layer 25a from absorbing light, the ohmic contact layer 25a can be formed in a predetermined area. For example, the ohmic contact layer 25a can be provided near the edge of the first LED stack 23 and can be arranged substantially in a ring shape. The contact area of ​​the ohmic contact layer 25a relative to the first LED stack 23 can be 25% or less, or in some exemplary embodiments can be 10% or less. Even if the contact area of ​​the ohmic contact layer 25a is relatively small, when the area of ​​the first LED stack 23 is approximately 200 square μm or less in size, the current can be evenly distributed in the first LED stack 23. The ohmic contact layer 25a can be formed of a transparent conductive oxide or an Au alloy such as Au(Zn) or Au(Be).

[0165] The reflective layer 25b may cover the lower surface of the ohmic contact layer 25a and the first LED stack 23. Figure 1As shown in FIG, the reflective layer 25b exposes the lower surface of the first LED stack 23 in the area surrounding the locations where the connectors 59a, 59b, 59c, and 59d are to be formed. 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 formed of Al, Ag, or the like. In addition, the reflective layer 25b may include a metal adhesion layer formed of Ti, Ta, Ni, Cr, or the like on the upper and lower surfaces of the reflective metal layer to improve the adhesion of the reflective metal layer. The reflective layer 25b may be formed of a metal layer that has a high reflectivity for light (e.g., red light) generated from the first LED stack 23. At the same time, the reflective layer 25b may have a relatively low reflectivity for light (e.g., 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 light generated from the second LED stack 33 and the third LED stack 43 and emitted toward the supporting substrate 51. Au has a high reflectivity for red light and a low reflectivity for green or blue light, and thus can be used to form the reflective layer 25b provided on the first LED stack 23.

[0166] 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 can be formed from 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 can be formed from a metal layer or a conductive oxide layer that is transparent to red, green, and blue light. The second and third transparent electrodes 35 and 45 can make ohmic contact with the p-type semiconductor layer of each LED stack to facilitate current distribution. Examples of conductive oxide layers for the second and third transparent electrodes 35 and 45 include SnO2, InO2, ITO, ZnO, IZO, and the like.

[0167] A first color filter 37 may be provided between the first LED stack 23 and the second LED stack 33. Furthermore, a second color filter 47 may be provided between the second LED stack 33 and the third LED stack 43. The first color filter 37 may transmit light generated from the first LED stack 23 and reflect light generated from the second LED stack 33. The second color filter 47 may transmit light generated from the first LED stack 23 and the second LED stack 33 and reflect light generated from the third LED stack 43. In this manner, light generated from the first LED stack 23 may be emitted to the outside through the second LED stack 33 and the third LED stack 43, and light generated from the second LED stack 33 may be emitted to the outside through the third LED stack 43. Furthermore, it is possible to prevent light generated from the second LED stack 33 from being incident on the first LED stack 23 and being lost, or to prevent light generated from the third LED stack 43 from being incident on the second LED stack 33 and being lost.

[0168] In some exemplary embodiments, the first color filter 37 may also reflect light generated from the third LED stack 43 .

[0169] The first color filter 37 and the second color filter 47 can be, for example, a low-pass filter through which only light in a low-frequency region (for example, light in a long wavelength region) passes, a band-pass filter through which only light in a specific wavelength region passes, or a band-stop filter that only blocks light in a specific wavelength region. More specifically, the first color filter 37 and the second color filter 47 can be formed by alternately stacking insulating layers with different refractive indices. For example, the color filter can be formed by alternately stacking TiO2 and SiO2. For example, the first color filter 37 and the second color filter 47 can include a distributed Bragg reflector (DBR). The stop band in the distributed Bragg reflector can be controlled by adjusting the thickness of TiO2 and SiO2. The low-pass filter and the band-pass filter can also be formed by stacking insulating layers with different refractive indices on each other.

[0170] The first bonding layer 55 bonds the first LED stack 23 to the substrate 51. As shown in the drawings, the first reflective electrode 25 may be in contact with the first bonding layer 55. The first bonding layer 55 may be a transmissive type or a non-transmissive type.

[0171] The second bonding layer 65 bonds the second LED stack 33 to the first LED stack 23. As shown in the drawings, the second bonding layer 65 may be in contact with the first LED stack 23 and the first color filter 37. The second bonding layer 65 may transmit light generated from the first LED stack 23. The second bonding layer 65 may be formed of, for example, spin-on glass having light transmittance.

[0172] The third bonding layer 75 bonds the third LED stack 43 to the second LED stack 33. As shown in the drawings, the third bonding layer 75 may be in contact with the second LED stack 33 and the second color filter 47. However, the inventive concept is not limited thereto, and a transparent conductive layer may be provided 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 may be formed of light-transmitting spin-on glass.

[0173] The bonding layers 55, 65, and 75 may be formed by forming a transparent organic layer or a transparent inorganic layer on each of two objects to be bonded and then bonding the objects to each other. Examples of the organic layer may include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc. Examples of the inorganic layer may include Al2O3, SiO2, SiN x The organic layers can be bonded under high vacuum and high pressure. The surface of the inorganic layer can be flattened by, for example, chemical mechanical polishing (CMP), and then the surface energy can be reduced by plasma or the like, and then bonded under high vacuum.

[0174] The first-1 connector 59d electrically connects the first reflective electrode 25 and the electrode pad 53d. Thus, the first-1 connector 59d is electrically connected to the lower surface of the first LED stack 23. As shown in the drawings, the first-1 connector 59d may pass through the first LED stack 23. However, the inventive concept is not limited thereto, and the first-1 connector 59d may be formed on a side surface of the first LED stack 23. An insulating layer 57 is interposed between the first-1 connector 59d and the first LED stack 23 to prevent the first-1 connector 59d from being short-circuited to the upper surface of the first LED stack 23.

[0175] The first-2 connector 59a electrically connects the upper surface of the first LED stack 23 and the electrode pad 53a on the substrate 51. The first-2 connector 59a can be connected to the upper surface of the first LED stack 23 and can pass through the first LED stack 23 to connect to the electrode pad 53a. An insulating layer 57 can be interposed between the first LED stack 23 and the first-2 connector 59a to prevent the first-2 connector 59a from being short-circuited to the lower surface of the first LED stack 23.

[0176] The first-3 connector 59b and the first-4 connector 59c may pass through the first LED stack 23 to connect to each of the electrode pads 53b and 53c. The first-3 connector 59b and the first-4 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.

[0177] The first-3 connector 59b and the first-4 connector 59c may be used as intermediate connectors, or these configurations may be omitted in some exemplary embodiments.

[0178] The second-1 connector 69d is provided 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 through the second transparent electrode 35. As shown in the drawings, the second-1 connector 69d may pass through the second LED stack 33. However, the inventive concept 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 being short-circuited to the upper surface of the second LED stack 33.

[0179] like Figure 2 As shown in FIG, the second-1 connector 69d can be connected to the first-1 connector 59d to be electrically connected to the electrode pad 53d. In this case, the first-1 connector 59d can be used as an intermediate connector. In addition, as shown in FIG. Figure 2 As shown in FIG, the second-1 connecting member 69d may be stacked on the first-1 connecting member 59d in the vertical direction.

[0180] The second-2 connector 69b is configured to electrically connect the upper surface of the second LED stack 33 to the electrode pad 53b. The second-2 connector 69b can be connected to the upper surface of the second LED stack 33 and can pass through the second LED stack 33. As shown in the drawings, the second-2 connector 69b can be connected to the first-3 connector 59b to electrically connect to the electrode pad 53b. The second-2 connector 69b can be directly connected to the electrode pad 53b. In this case, the first-3 connector 59b is omitted.

[0181] An insulating layer 67 may be interposed between the second LED stack 33 and the second-2 connector 69 b to prevent the second-2 connector 69 b from being short-circuited to a lower surface of the second LED stack 33 .

[0182] The second-3 connector 69c may be provided to pass through the second LED stack 33. The second-3 connector 69c may be electrically connected to the electrode pad 53c and may be connected to, for example, the first-4 connector 59c. The second-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 second-3 connector 69c.

[0183] The second-3 connector 69c may be used as an intermediate connector, or these configurations may be omitted in some exemplary embodiments.

[0184] The third-1 connector 79d is provided 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 through the third transparent electrode 45. As shown in the drawings, the third-1 connector 79d may pass through the third LED stack 43. However, the inventive concept is not limited thereto, and the third-1 connector 79d may be formed on the 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 being short-circuited to the upper surface of the third LED stack 43.

[0185] like Figure 2 As shown in FIG, the third-1 connector 79d can be connected to the second-1 connector 69d to be electrically connected to the electrode pad 53d. In this case, the second-1 connector 69d and the first-1 connector 59d can be used as intermediate connectors. In addition, as shown in FIG. Figure 2 As shown in , the third-1 connector 79d can be stacked on the second-1 connector 69d in the vertical direction. Therefore, the first-1 connector 59d, the second-1 connector 69d and the third-1 connector 79d are electrically connected to each other and stacked in the vertical direction. The connectors are arranged in the direction of light emission to absorb light. In the case where the connectors are arranged to be spaced apart from each other in the lateral direction, the light-emitting area will be reduced and the light loss will increase. However, the connectors according to the exemplary embodiment are stacked in the vertical direction to reduce the loss of light generated from the first LED stack 23 and the second LED stack 33 through the connectors.

[0186] The third-2 connector 79c is provided to connect the upper surface of the third LED stack 43 and the electrode pad 53c. The third-2 connector 79c can be connected to the upper surface of the third LED stack 43 and can pass through the third LED stack 43. As shown in the drawings, the third-2 connector 79c can be connected to the second-3 connector 69c to electrically connect to the electrode pad 53c. The third-2 connector 79c can be directly connected to the electrode pad 53c. In this case, the second-3 connector 69c can be omitted.

[0187] Meanwhile, an insulating layer 77 may be interposed between the third LED stack 43 and the third-2 connection member 79 c to prevent the third-2 connection member 79 c from being short-circuited to the lower surface of the third LED stack 43 .

[0188] As shown in the drawings, the third-2 connecting member 79 c , the second-3 connecting member 69 c , and the first-4 connecting member 59 c may be stacked in a vertical direction, which may reduce light loss.

[0189] To prevent light interference between pixels caused by light emitted from the first, second, and third LED stacks 23, 33, and 43 to the side surfaces of the first, second, and third LED stacks 23, 33, and 43, a light-reflecting layer or a light-blocking material layer can be formed to cover the side surfaces of the first to third LED stacks 23, 33, and 43. Examples of the light-reflecting layer may include a distributed Bragg reflector, or may include an insulating layer formed of SiO2 and a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. For example, black epoxy resin can be used as the light-blocking layer. The light-blocking material prevents light interference between the light-emitting elements to improve the contrast of the image.

[0190] According to an exemplary embodiment, the first LED stack 23 is electrically connected to the electrode pads 53d and 53a, the second LED stack 33 is electrically connected to the electrode pads 53d and 53b, and the third LED stack 43 is electrically connected to the electrode pads 53d and 53c. In this way, the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 are commonly (commonly) electrically connected to the electrode pad 53d, and the cathodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 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 driven independently. In addition, these LED stacks 23, 33, and 43 can be arranged on a thin film transistor substrate 51 and can be electrically connected to the internal circuit of the substrate 51 so as to be driven in an active matrix manner.

[0191] Figure 3A 、 Figure 3B 、 Figure 4A 、 Figure 4B 、 Figure 5A 、 Figure 5B 、 Figure 6A 、 Figure 6B 、 Figure 7A 、 Figure 7B 、 Figure 8A 、 Figure 8B 、 Figure 9A 、 Figure 9B 、 Figure 10A 、 Figure 10B 、 Figure 11A 、 Figure 11B 、 Figure 12A 、 Figure 12B 、 Figure 13A 、 Figure 13B 、 Figure 14A 、 Figure 14B 、 Figure 15A 、 Figure 15B 、 Figure 16A and Figure 16BSchematic plan view and schematic cross-sectional view illustrating a method of manufacturing a display device according to an exemplary embodiment of the present disclosure. Figure 1 The plan view corresponds to that of Figure 1 The line AA is intercepted.

[0192] First, refer to Figure 3A and Figure 3B The first LED stack 23 is grown on the first substrate 21. The first substrate 21 may be, for example, a GaAs substrate. 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.

[0193] An ohmic contact layer 25a and a reflective layer 25b are formed on the first LED stack 23 to form a first reflective electrode 25. The ohmic contact layer 25a may be formed by using a lift-off technique or the like, and may be formed to be disposed near an edge of the first LED stack 23. As shown in the drawings, the ohmic contact layer 25a may be formed to have a substantially ring shape.

[0194] The reflective layer 25b covers the ohmic contact layer 25a and also covers the first LED stack 23. The reflective layer 25b can be formed to expose each of the edges of the first LED stack 23. More specifically, the reflective layer 25b can have an opening 25h that exposes the first LED stack 23 through the ohmic contact layer 25a. The reflective layer 25b can be formed, for example, of Au and can be formed using a lift-off technique or the like.

[0195] Reference Figure 4A and Figure 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 may be 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 may 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. The second transparent electrode 35 is in ohmic contact with the p-type semiconductor layer.

[0196] Reference Figure 5A and Figure 5BA 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 may be 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 may 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. The third transparent electrode 45 is in ohmic contact with the p-type semiconductor layer.

[0197] The first color filter 37 and the second color filter 47 are aligned with the reference Figure 1 The described first color filter 37 and second color filter 47 are substantially the same, and thus their detailed descriptions will be omitted to avoid redundancy.

[0198] Reference Figure 6A and Figure 6B , electrode pads 53a, 53b, 53c, and 53d are formed on a substrate 51. The substrate 51 may be a substrate formed of Si in which a thin film transistor is located. Each of the electrode pads 53a, 53b, 53c, and 53d corresponding to one pixel region may be provided in each of the four edge regions of the substrate 51.

[0199] The first LED stack 23 , the second LED stack 33 , the third LED stack 43 , and the electrode pads 53 a , 53 b , 53 c , and 53 d are separately formed on different substrates, and their formation order is not particularly limited.

[0200] Reference Figure 7A and Figure 7B , the first LED stack 23 is bonded to the substrate 51 via the first bonding layer 55. The first bonding layer 55 can be provided on the substrate 51, and the first reflective electrode 25 is provided facing the substrate 51 so that the first reflective electrode 25 is bonded to the first bonding layer 55. Alternatively, a bonding material layer can be formed on each of the substrate 51 and the first LED stack 23, and then the first LED stack 23 can be bonded to the substrate 51 by bonding the bonding material layers to each other. At the same time, the first substrate 21 can be removed from the first LED stack 23 by chemical etching or the like. In this way, the n-type semiconductor layer of the first LED stack 23 is exposed on the upper surface. The exposed n-type semiconductor layer can be subjected to surface texturing.

[0201] Reference Figure 8A and Figure 8BThe first LED stack 23 is patterned to expose a portion of the first reflective electrode 25. To avoid damage to 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 for exposing the electrode pads 53a, 53b, 53c, and 53d.

[0202] Reference Figure 9A and Figure 9B An insulating layer 57 is formed in the opening to cover the side surfaces of the first LED stack 23. The insulating layer 57 may also partially cover the upper 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.

[0203] Reference Figure 10A and Figure 10B , forming connectors 59a, 59b, 59c, and 59d that can be connected to the exposed electrode pads 53a, 53b, 53c, and 53d, respectively. The first-1 connector 59d is connected to the first reflective electrode 25 and is also connected 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 via the first-1 connector 59d. In addition, the first-2 connector 59a is connected to the upper surface of the first LED stack 23 and is also connected 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 via the first-2 connector 59a. The first-3 connector 59b and the first-4 connector 59c are insulated from the first LED stack 23 by the insulating layer 57.

[0204] Reference Figure 11A and Figure 11B , through the second bonding layer 65 Figure 4A and Figure 4BThe second LED stack 33 is bonded to the first LED stack 23 on which the first-1 connector 59d, the first-2 connector 59a, the first-3 connector 59b and the first-4 connector 59c are formed. The first color filter 37 is bonded to the second bonding layer 65 and is arranged to face the first LED stack 23. The second bonding layer 65 can be set on the first LED stack 23 in advance. The first color filter 37 can be bonded to the second bonding layer 65 and is arranged to face the second bonding layer 65. Alternatively, a bonding material layer can be formed on each of the first LED stack 23 and the first color filter 37, and the bonding material layers can be bonded to each other to bond the second LED stack 33 to the first LED stack 23. At the same time, the second substrate 31 can be separated from the second LED stack 33 by using laser lift-off, chemical lift-off technology, etc. Therefore, the n-type semiconductor layer of the second LED stack 33 is exposed. The exposed n-type semiconductor layer can be subjected to surface texturing by chemical etching, etc. However, the step of texturing the surface of the second LED stack 33 may be omitted in some exemplary embodiments.

[0205] Reference Figure 12A and Figure 12B The second LED stack 33 is patterned to expose the second transparent electrode 35, and the exposed second transparent electrode 35, the first color filter 37, and the second bonding layer 65 are etched to form an opening for exposing the first-1 connector 59d. In addition, openings for exposing the first-3 connector 59b and the first-4 connector 59c can also be formed together.

[0206] Reference Figure 13A and Figure 13B , an insulating layer 67 is formed to cover the side surfaces of the exposed opening. The insulating layer 67 exposes the second transparent electrode 35 and also exposes the first-1 connector 59d, the first-3 connector 59b, and the first-4 connector 59c.

[0207] A second-1 connector 69d, a second-2 connector 69b, and a second-3 connector 69c are formed in the opening. The second-1 connector 69d electrically connects the second transparent electrode 35 and the first-1 connector 59d to each other and is insulated from the upper surface of the second LED stack 33 by the insulating layer 67. The second-2 connector 69b is connected to the upper surface of the second LED stack 33 and to the first-3 connector 59b. The second-2 connector 69b is electrically connected to the electrode pad 53b through the first-3 connector 59b. The second-2 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.

[0208] Meanwhile, the second-3 connection 69 c is connected to the first-4 connection 59 c and is insulated from the second LED stack 33 and the second transparent electrode 35 by the insulating layer 67 .

[0209] Reference Figure 14A and Figure 14B , through the third bonding layer 75 Figure 5A and Figure 5B The third LED stack 43 is bonded to the second LED stack 33 on which the second-1 connector 69d, the second-2 connector 69b, and the second-3 connector 69c are formed. The second color filter 47 is bonded to the third bonding layer 75 and is arranged to face the second LED stack 33. The third bonding layer 75 can be provided on the second LED stack 33 in advance, and the second color filter 47 can be bonded to the third bonding layer 75 and be arranged to face the third bonding layer 75. Alternatively, a bonding material layer can be formed on each of the second LED stack 33 and the second color filter 47, and the bonding material layers can be bonded to each other to bond the third LED stack 43 to the second LED stack 33. At the same time, the third substrate 41 can be separated from the third LED stack 43 by laser lift-off, chemical lift-off technology, 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 can be subjected to surface texturing by chemical etching, etc.

[0210] Reference Figure 15A and Figure 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 second-1 connector 69d. In addition, an opening for exposing the second-3 connector 69c may also be formed.

[0211] Reference Figure 16A and Figure 16B An insulating layer 77 is formed to cover the side surfaces of the exposed opening. The insulating layer 77 exposes the third transparent electrode 45 and also exposes the second-1 connecting member 69d and the second-3 connecting member 69c.

[0212] A third-1 connector 79d and a third-2 connector 79c are formed in the opening. The third-1 connector 79d electrically connects the third transparent electrode 45 and the second-1 connector 69d to each other and is insulated from the upper surface of the third LED stack 43 by the insulating layer 77. The third-2 connector 79c is connected to the upper surface of the third LED stack 43 and to the second-3 connector 69c. The third-2 connector 79c is electrically connected to the electrode pad 53c through the second-3 connector 69c and the first-4 connector 59c. The third-2 connector 79c is insulated from the lower surface of the third LED stack 43 and the third transparent electrode 45 by the insulating layer 77.

[0213] According to an exemplary embodiment, a unit pixel in which anodes of the first to third LED stacks 23 , 33 , and 43 are electrically connected in common to each other and cathodes thereof are independently connected may be provided.

[0214] Although the method of manufacturing one unit pixel has been described above according to the exemplary embodiment, the display device may include a plurality of unit pixels arranged in a matrix on the substrate 51. These unit pixels are spaced apart from each other. In this case, the regions of the first to third LED stacks 23, 33, and 43, each corresponding to a unit pixel, may be isolated from each other in advance on the substrates 21, 31, and 41. Alternatively, when each of the LED stacks 23, 33, and 43 is patterned after being bonded to the substrate 51, the region of the LED stack may be isolated as a region corresponding to each pixel region. Therefore, the display device having a plurality of unit pixels on the substrate 51 according to the exemplary embodiment can eliminate the need to separately install pixels having a small size.

[0215] Furthermore, to prevent light interference between pixels, a light-reflecting layer or light-blocking material layer can be added to cover the sides of the pixels. Examples of light-reflecting layers include distributed Bragg reflectors or an insulating layer formed of SiO2 with a reflective metal layer or a highly reflective organic layer deposited on the insulating layer. For example, black epoxy resin can be used as a light-blocking layer. Light-blocking materials prevent light interference between light-emitting elements, thereby improving image contrast.

[0216] Figure 17 is a schematic plan view of a display device according to another exemplary embodiment. Figure 18 It is along Figure 17 A schematic cross-sectional view taken along line BB of FIG.

[0217] Reference Figure 17 and Figure 18 , except that the cathodes of the first to third LED stacks 23, 33, and 43 are commonly electrically connected to each other and the anodes of the first to third LED stacks 23, 33, and 43 are independently connected, the display device according to the exemplary embodiment is different from the reference Figure 1 and Figure 2 The display devices described are generally similar.

[0218] Specifically, the first-1 connector 159d electrically connects the first reflective electrode 25 to the electrode pad 153d, the second-1 connector 169a electrically connects the second transparent electrode 35 to the electrode pad 153a, and the third-1 connector 179b electrically connects the third transparent electrode 45 to the electrode pad 153b.

[0219] In addition, the first-2 connector 159c is connected to the upper surface of the first LED stack 23 and the electrode pad 153c. The second-2 connector 169c is connected to the upper surface of the second LED stack 33 and the first-2 connector 159c. The third-2 connector 179c is connected to the upper surface of the third LED stack 43 and the second-2 connector 169c. As shown in the figure, the first-2 connector 159c, the second-2 connector 169c, and the third-2 connector 179c can be stacked in the vertical direction. In addition, the third-1 connector 179b can be connected to the electrode pad 153b through the intermediate connectors 169b and 159b, and the connectors 159b, 169b, and 179b can also be stacked in the vertical direction.

[0220] Figure 19 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0221] Reference Figure 19 , according to an exemplary embodiment, the driving circuit includes two or more transistors, transistors Tr1 and Tr2, and a capacitor. When power is connected to the selection lines Vrow1 to Vrow3 and the data voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diode. The charge is charged to the corresponding capacitor according to the value of Vdata1 to Vdata3. Because the conduction state of the transistor Tr2 is maintained by the charged voltage of the capacitor, the voltage of the capacitor can be maintained even if the power is disconnected, and the voltage can be 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 Vdata1 to Vdata3. The current can be constantly provided by the current source Vdd, so continuous light emission is possible.

[0222] Transistors Tr1 and Tr2 and a capacitor may be formed in substrate 51. Here, light-emitting diodes LED1 to LED3 correspond to first to third LED stacks 23, 33, and 43, respectively, stacked as one pixel. The anodes of the first to third LED stacks are connected to transistor Tr2, and their cathodes are grounded. According to an exemplary embodiment, the first to third LED stacks 23, 33, and 43 may be commonly connected to each other to be grounded.

[0223] although Figure 19 , a circuit diagram for driving an active matrix according to an exemplary embodiment is shown in FIG. However, the inventive concept is not limited thereto, and another circuit may be used. Furthermore, although the anodes of the light-emitting diodes LED1 to LED3 are each described as being connected to a different transistor Tr2 and their cathodes are described as being grounded, in some exemplary embodiments, the anodes of the first to third LED stacks 23, 33, and 43 may be commonly connected and their respective cathodes may be connected to different transistors.

[0224] Figure 20 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0225] Reference Figure 20 , the display device includes a circuit board 201 and a plurality of light emitting devices 200 .

[0226] 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 wiring and resistors located therein. In another exemplary embodiment, the circuit board 201 may include wiring, transistors, and capacitors. The circuit board 201 may also have pads (also known as "solder pads") on the upper side of the circuit board 201 so that the circuits disposed therein can be electrically connected.

[0227] A plurality of light-emitting devices 200 are arranged on a circuit board 201. Each light-emitting device 200 constitutes a pixel. The light-emitting devices 200 have electrode pads 281a, 281b, 281c, and 281d, and the electrode pads 281a, 281b, 281c, and 281d are electrically connected to the circuit board 201. The light-emitting devices 200 may also include a substrate 241 on their upper surfaces. Since the light-emitting devices 200 are spaced apart from each other, the substrate 241 disposed on the upper surfaces of the light-emitting devices 200 are also spaced apart from each other.

[0228] Will refer to Figure 21A and Figure 21B A specific configuration of the light emitting device 200 is described in detail. Figure 21A is a schematic plan view of a light emitting device 200 according to an exemplary embodiment, Figure 21B It is along Figure 21AAlthough the electrode pads 281a, 281b, 281c and 281d are shown as being arranged on the upper side, the inventive concept is not limited thereto, and the light emitting device 200 may be flip-chip bonded on the upper side. Figure 20 , and in this case, the electrode pads 281a, 281b, 281c and 281d will be arranged on the lower side.

[0229] Reference Figure 21A and Figure 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.

[0230] The substrate 241 may also support the LED stacks 223, 233, and 243. In addition, the substrate 241 may 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, specifically, a patterned sapphire substrate. The first LED stack, the second LED stack, and the third LED stack 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 provided on one substrate 241, and thus, the light-emitting device 200 has a single-chip structure of a single pixel. In some exemplary embodiments, the substrate 241 may be omitted, and the lower surface of the third LED stack 243 may be exposed. In this case, a rough surface may be formed on the lower surface of the third LED stack 243 by surface texturing.

[0231] Each of the first LED stack 223, the second LED stack 233, and the third LED stack 243 includes a first conductive semiconductor layer 223a, 233a, or 243a, a second conductive semiconductor layer 223b, 233b, or 243b, and an active layer interposed between the first conductive semiconductor layer 223a, 233a, or 243a and the second conductive semiconductor layer 223b, 233b, or 243b. Specifically, the active layer may have a multi-quantum well structure.

[0232] The closer to the substrate 241, the shorter the wavelength of light emitted from the LED stack can be. For example, the first LED stack 223 can be an inorganic light emitting diode that emits red light, the second LED stack 233 can be an inorganic light emitting diode that emits green light, and the third LED stack 243 can be an inorganic light emitting diode that emits blue light. The first LED stack 223 can include a GaInP base well layer, and the second LED stack 233 and the third LED stack 243 can include a GaInN base well layer. However, the inventive concept is not limited thereto, and when the light emitting device 200 includes a micro-LED, the first LED stack 223 can emit any one of red, green, and blue light, and the second LED stack 233 and the third LED stack 243 can emit a different one of red, green, and blue light without adversely affecting the operation due to the small form factor of the micro-LED.

[0233] The first conductive semiconductor layers 223a, 233a, and 243a of each LED stack 223, 233, and 243 may be n-type semiconductor layers, and the second conductive semiconductor layers 223b, 233b, and 243b of each LED stack 223, 233, and 243 may be p-type semiconductor layers. The upper surface of the first LED stack 223 may be a p-type semiconductor layer 223b, the upper surface of the second LED stack 233 may be an n-type semiconductor layer 233a, and the upper surface of the third LED stack 243 may be a p-type semiconductor layer 243b. More specifically, according to an exemplary embodiment, the order of the semiconductor layers is reversed only in the second LED stack 233. The first and third LED stacks 223 and 243 may have first conductive semiconductor layers 223a and 243a with textured surfaces to improve light extraction efficiency. The second LED stack 233 may also have a first conductive semiconductor layer 233a with a textured surface. However, because the first conductive semiconductor layer 233a is disposed farther from the substrate 241 than the second conductive semiconductor layer 233b, the surface texturing may be less effective. More specifically, when the second LED stack 233 emits green light, green light has higher visibility than red or blue light. Therefore, it may be preferable that the luminous efficiency of the first LED stack 223 and the third LED stack 243 be increased more than the luminous efficiency of the second LED stack 233. In this way, the luminous intensities of red, green, and blue light can be adjusted or balanced to maintain similar levels by applying surface texturing to the first LED stack 223 and the third LED stack 243, thereby improving light extraction efficiency while using the second LED stack 233 with no or less surface texturing.

[0234] In the first LED stack 223 and the third LED stack 243, the second conductive type semiconductor layers 223b and 243b may be provided 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 case of the second LED stack 233, the first conductive type semiconductor layer 233a and the second conductive type semiconductor layer 233b may be completely overlapped.

[0235] The first LED stack 223 is disposed spaced 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. The first LED stack 223 can emit light having a longer wavelength than the second LED stack 233 and the third LED stack 243, so that the light generated in the first LED stack 223 is emitted to the outside through the second LED stack 233, the third LED stack 243, and the substrate 241. Furthermore, the second LED stack 233 can emit light having a longer wavelength than the third LED stack 243, so that the light generated in the second LED stack 233 is emitted to the outside through the third LED stack 243 and the substrate 241. However, the inventive concept is not limited thereto. For example, when the light emitting device 200 includes a micro-LED, the first LED stack 223 can emit any one of red, green, and blue light, and the second LED stack 233 and the third LED stack 243 can emit a different one of red, green, and blue light without adversely affecting operation due to the small form factor of the micro-LED.

[0236] The insulating layer 271 is provided on the first LED stack 223 and has an opening for exposing the second conductive semiconductor layer 223 b 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 lower refractive index than that of the first LED stack 223.

[0237] The first reflective electrode 228 makes ohmic contact with the second conductive semiconductor layer 223 b 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 is connected to the first LED stack 223 through an opening of the insulating layer 271.

[0238] The first reflective electrode 228 may include an ohmic contact layer 228a and a reflective layer 228b. The ohmic contact layer 228a partially contacts the second conductive type semiconductor layer 223b (e.g., a p-type semiconductor layer). The ohmic contact layer 228a may be formed in a predetermined region to prevent the ohmic contact layer 228a from absorbing light. The ohmic contact layer 228a may be formed on the second conductive type semiconductor layer 223b exposed in the opening of the insulating layer 271. The ohmic contact layer 228a may be formed to have a substantially annular shape. The ohmic contact layer 228a may be formed of a transparent conductive oxide or an Au alloy such as Au(Zn) or Au(Be).

[0239] 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 comprising 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, which can form an omnidirectional reflector. The reflective layer 228b may include a reflective metal layer such as Al, Ag, or Au. In addition, the reflective layer 228b may include an adhesive metal layer such as Ti, Ta, Ni, or Cr on the upper and lower surfaces of the reflective metal layer. Au is particularly suitable for forming the reflective layer 228b in the first LED stack 223 due to its high reflectivity for red light and its low reflectivity for blue or green light. The reflective layer 228b may cover greater than approximately 50% of the area (or surface) of the first LED stack 223, and may also cover a majority of the area to improve light efficiency.

[0240] The ohmic contact layer 228a and the reflective layer 228b may be formed of a metal layer containing Au. The reflective layer 228b may be formed of a metal layer having high reflectivity for light (e.g., red light) generated in the first LED stack 223. The reflective layer 228b may have a relatively low reflectivity for light (e.g., 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 LED stack 233 and the third LED stack 243 and incident on the reflective layer 228b may be absorbed to reduce optical interference.

[0241] The first ohmic electrode 226 is disposed on the exposed first conductive type semiconductor layer 223a and is in ohmic contact with the first conductive type semiconductor layer 223a. The first ohmic electrode 226 may also be formed of a metal layer including Au.

[0242] The second transparent electrode 235 makes ohmic contact with the second conductive semiconductor layer 233b of the second LED stack 233. As shown in the figure, the second transparent electrode 235 contacts 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 can be formed of a conductive oxide layer or a metal layer that is transparent to red and blue light.

[0243] Furthermore, the third transparent electrode 245 makes ohmic contact with the second conductive semiconductor layer 243b of the third LED stack 243. The third transparent electrode 245 may be disposed between the second LED stack 233 and the third LED stack 243 and contact the upper surface of the third LED stack 243. The third transparent electrode 245 may be formed of a conductive oxide layer or a metal layer that is transparent to red and green light. According to some exemplary embodiments, the third transparent electrode 245 may also be transparent to blue light. The second and third transparent electrodes 235, 245 may facilitate current distribution by making ohmic contact with the p-type semiconductor layer of each LED stack. Examples of conductive oxide layers for the second and third transparent electrodes 235, 245 include SnO2, InO2, ITO, ZnO, IZO, and the like.

[0244] A first color filter 247 may be disposed between the third transparent electrode 245 and the second LED stack 233, and a second color filter 267 may be disposed between the second LED stack 233 and the first LED stack 223. The first color filter 247 may transmit light generated in the first and second LED stacks 223 and 233, and may reflect light generated in the third LED stack 243. The second color filter 267 may transmit light generated in the first LED stack 223 and may reflect light generated in the second LED stack 233. Therefore, light generated in the first LED stack 223 may be emitted to the outside through the second and third LED stacks 233 and 243, and light generated in the second LED stack 233 may be emitted to the outside through the third LED stack 243. Furthermore, light generated in the second LED stack 233 may be prevented from being lost due to incident on the first LED stack 223, and light generated in the third LED stack 243 may be prevented from being lost due to incident on the second LED stack 233.

[0245] In some exemplary embodiments, the second color filter 267 may reflect light generated in the third LED stack 243 .

[0246] The first color filter 247 and the second color filter 267 can be, for example, a low-pass filter that only allows a low frequency band such as a long wave band to pass, a band-pass filter that only allows a predetermined wave band to pass, or a band-stop filter that only blocks a predetermined wave band. Specifically, the first color filter 247 and the second color filter 267 can be formed by alternately stacking insulating layers having different refractive indices from each other, for example, by alternately stacking TiO2 insulating layers and SiO2 insulating layers. Specifically, the first color filter 247 and the second color filter 267 can include a distributed Bragg reflector (DBR). The stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 layer and the SiO2 layer. The low-pass filter and the band-pass filter can also be formed by alternately stacking insulating layers having different refractive indices from each other.

[0247] 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 can 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), and examples of inorganic layers include Al2O3, SiO2, SiN x The organic layer can be bonded under high vacuum and high pressure, and the inorganic layer can be bonded under high vacuum after the surface is planarized by a chemical mechanical polishing process and then the surface energy is reduced by using plasma or the like.

[0248] The second bonding layer 269 bonds the second LED stack 233 to the first LED stack 223. As shown in the drawings, the second bonding layer 269 may cover the second color filter 267 and may be in contact with the first LED stack 223. However, the inventive concept is not limited thereto, and another layer such as a transparent electrode layer may be provided on the lower surface of the first LED stack 223. The second bonding layer 269 may be formed of substantially the same material as the first bonding layer 249 described above.

[0249] The upper insulating layer 273 covers the side surfaces and upper portion of the first LED stack 223, the second LED stack 233, and the third LED stack 243. The upper insulating layer 273 can be formed of SiO2, Si3N4, SOG, etc. Optionally, the upper insulating layer 273 can include a light-reflecting material or a light-blocking material to prevent optical interference with adjacent light-emitting devices. For example, the upper insulating layer 273 can include a distributed Bragg reflector that reflects red, green, and blue light, or can include a SiO2 layer with a reflective layer or a highly reflective organic layer deposited thereon. Alternatively, for example, the upper insulating layer 273 can include black epoxy as a light-blocking material. The light-blocking material improves the contrast of the image by preventing optical interference between the light-emitting devices.

[0250] The upper insulating layer 273 has openings for exposing the first ohmic electrode 26, the first reflective electrode 228, the second transparent electrode 235, the third transparent electrode 245, the second LED stack 233, and the third LED stack 243. A hole may be formed through the first LED stack 223 and the second LED stack 233, and the upper insulating layer 273 may cover the sidewalls of the hole while exposing the bottom surface of the hole.

[0251] Electrode pads 281a, 281b, 281c, and 281d are disposed over the first LED stack 223 and are electrically connected to the first LED stack 223, the second LED stack 233, and the third LED stack 243. The electrode pads 281a, 281b, 281c, and 281d may be disposed on the upper insulating layer 273 and may be connected to the first ohmic electrode 26, the first reflective electrode 228, the second transparent electrode 235, the third transparent electrode 245, the second LED stack 233, and the third LED stack 243 exposed through the holes h1, h2, h3, h4, and h5.

[0252] For example, the first electrode pad 281a may be connected to the first ohmic electrode 26 through a hole h4 passing through the upper insulating layer 273. The first electrode pad 281a is electrically connected to the first conductive type semiconductor layer 223a of the first LED stack 223.

[0253] The second electrode pad 281 b may be connected to the first conductive type semiconductor layer 233 a of the second LED stack 233 through a hole h3 passing through the upper insulating layer 273 and the first LED stack 223 .

[0254] The third electrode pad 281c may be connected to the first conductive type semiconductor layer 243a of the third LED stack 243 through a hole h2 passing through the upper insulating layer 273, the first LED stack 223, and the second LED stack 233. The hole h2 may pass through the second conductive type semiconductor layer 243b and the active layer of the third LED stack 243.

[0255] At the same time, the common electrode pad 281d can be commonly connected to the first reflective electrode 228, the second transparent electrode 235, and the third transparent electrode 245 through the holes h1 and h5. The hole h1 passes through 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 Figure 21B As shown in FIG, the common electrode pad 281 d may be connected to the third LED stack 243 through a hole h1 passing through a hollow portion surrounded by the first reflective electrode 228 .

[0256] According to an exemplary embodiment, the first LED stack 223 is electrically connected to electrode pads 281d and 281a, the second LED stack 233 is electrically connected to electrode pads 281d and 281b, and the third LED stack 243 is electrically connected to 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 electrically connected to the electrode pad 281d in common, and the cathodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243 are electrically connected to the first electrode pad 281a, the second electrode pad 281b, and the third electrode pad 281c, respectively. Therefore, the first LED stack 223, the second LED stack 233, and the third LED stack 243 can be driven independently.

[0257] Figure 22 、 Figure 23 、 Figure 24 、 Figure 25 、 Figure 26A 、 Figure 26B 、 Figure 27A 、 Figure 27B 、 Figure 28A 、 Figure 28B 、 Figure 29 、 Figure 30A 、 Figure 30B 、 Figure 31A 、 Figure 31B 、 Figure 32A 、 Figure 32B 、 Figure 33A 、 Figure 33B 、 Figure 34A 、 Figure 34B 、 Figure 35A and Figure 35B Schematic plan view and cross-sectional view showing a method of manufacturing a light emitting device 200 according to an exemplary embodiment. Figure 21A The plan view corresponds to that of Figure 21A The line AA is intercepted.

[0258] First, refer to Figure 22 , a first LED stack 223 is grown on a first substrate 221. For example, the first substrate 221 may be 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. Here, the first conductivity type may be n-type and the second conductivity type may be p-type.

[0259] Reference Figure 23 A second LED stack 233 is grown on the 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. Here, the first conductivity type may be n-type and the second conductivity type may be p-type.

[0260] 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. For example, the composition ratio of the GaInN well layer can be determined so that the second LED stack 233 emits green light. The second transparent electrode 235 is in ohmic contact with the second conductive semiconductor layer 233b. The second transparent electrode 235 can be formed of a conductive oxide layer such as SnO2, InO2, ITO, ZnO, or IZO.

[0261] Reference Figure 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 also include a GaInN well layer. Here, the first conductivity type may be n-type and the second conductivity type may be p-type.

[0262] 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. For example, the composition ratio of the GaInN well layer can be determined so that the third LED stack 243 emits blue light. The third transparent electrode 245 is in ohmic contact with the second conductive semiconductor layer 243b. The third transparent electrode 245 can be formed of a conductive oxide layer such as SnO2, InO2, ITO, ZnO, or IZO.

[0263] Since the first color filter 247 is Figure 21A and Figure 21B The described first color filter 247 is substantially the same, so its detailed description will be omitted to avoid redundancy.

[0264] Reference Figure 25 ,Will Figure 23 The second LED stack 233 is bonded to Figure 24 On the third LED stack 243.

[0265] The first color filter 247 and the second transparent electrode 235 are bonded to face each other. For example, bonding material layers are formed on the first color filter 247 and the second transparent electrode 235, respectively, and by bonding the first color filter 247 and the second transparent electrode 235, a first bonding layer 249 can be formed. The bonding material layer can be, for example, a transparent organic layer or a transparent inorganic layer. Examples of organic layers include SU8, poly (methyl methacrylate) (PMMA), polyimide, polyparaxylene, benzocyclobutene (BCB), etc., and examples of inorganic layers include Al2O3, SiO2, SiN x The organic layers can be bonded under high vacuum and high pressure, and the inorganic layers can be bonded under high vacuum after the surface energy is reduced by, for example, chemical mechanical polishing (CMP) and the like.

[0266] Then, the second substrate 231 is removed from the second LED stack 233 using a technique such as laser lift-off or chemical lift-off. As a result, the first conductive semiconductor layer 233a of the second LED stack 233 is exposed from above. The surface of the exposed first conductive semiconductor layer 233a may be textured.

[0267] Meanwhile, before bonding the first LED stack 223 to the second LED stack, 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. This will be referred to as Figure 26A 、 Figure 26B 、 Figure 27A 、 Figure 27B 、 Figure 28A 、 Figure 28B and Figure 29 Described in detail below.

[0268] Reference Figure 26A and Figure 26B ,Will Figure 22 The second conductive type semiconductor layer 223b of the first LED stack 223 is patterned to expose the first conductive type semiconductor layer 223a. The light emitting device region may substantially have the following Figure 26AHere, the second conductive type semiconductor layer 223b is removed near the four corners of one light emitting device region. Figure 26A As shown in , the second conductive type semiconductor layer 223b may be removed near three corners, and a hole may be formed through the second conductive type semiconductor layer 223b near one corner. Here, although one light emitting device region is shown, a plurality of light emitting device regions may be provided on the substrate 241, and the second conductive type semiconductor layer 223b may be patterned in each light emitting device region according to some exemplary embodiments.

[0269] Reference Figure 27A and Figure 27B A first ohmic electrode 226 is formed near one corner. The first ohmic electrode 26 is in ohmic contact with the first conductive type semiconductor layer 223a.

[0270] Next, an insulating layer 271 is formed and patterned to cover the first ohmic electrode 226 and the first LED stack 223, forming an opening for exposing the second conductive semiconductor layer 223b. For example, SiO2 is formed on the first LED stack 223, a photoresist is applied to the SiO2, and then a photoresist pattern is formed using photolithography and development. The SiO2 is then patterned using the photoresist pattern as an etching mask to form the insulating layer 271 having the opening.

[0271] The opening may be formed around the hole passing through the second conductive type semiconductor layer 223 b and may be substantially in a ring shape surrounding the hole.

[0272] Then, an ohmic contact layer 228a is formed in the opening of the insulating layer 271. The ohmic contact layer 228a may be formed using a lift-off technique, etc. The ohmic contact layer 228a may be formed in a substantially ring shape along the shape of the opening.

[0273] Reference Figure 28A and Figure 28B After forming the ohmic contact layer 228a, a reflective layer 228b is formed to cover the ohmic contact layer 228a and the insulating layer 271. The reflective layer 228b may be formed using a lift-off technique, etc. The first reflective electrode 228 is formed of the ohmic contact layer 228a and the reflective layer 228b.

[0274] As shown in the accompanying drawings, the first reflective electrode 228 may have a shape with four corners removed from a rectangular light-emitting device region. Specifically, the first reflective electrode 228 may have a hollow portion at one corner above a hole formed in the second conductive semiconductor layer 223b. Although a single light-emitting device region is shown, multiple light-emitting device regions may be provided on the substrate 221, and according to some exemplary embodiments, the first reflective electrode 228 may be formed in each light-emitting device region.

[0275] Reference Figure 29 , bonding the carrier substrate 251 to Figure 28A and Figure 28B The first LED stack 223 is disposed on the first reflective electrode 228. The first reflective electrode 228 is positioned facing the carrier substrate 251, and the first LED stack 223 can be bonded to the carrier substrate 251 using a bonding layer 253. The substrate 221 is then removed from the first LED stack 223. This exposes the first conductive semiconductor layer 223a. The surface of the exposed first conductive semiconductor layer 223a can be textured to improve light extraction efficiency, thereby forming a rough surface or a light extraction structure on the surface of the first conductive semiconductor layer 223a.

[0276] In the following, combined Figure 25 , a method of manufacturing the light emitting device 200 by bonding the first LED stack 223 to the second LED stack 233 will be described.

[0277] Reference Figure 30A and Figure 30B , first of all, in Figure 25 The second color filter 267 is formed on the exposed first conductive type semiconductor layer 233a of the second LED stack 233. Figure 21A and Figure 21B The described second color filter 267 is substantially the same, so a detailed description thereof will be omitted.

[0278] The first LED stack 223 is bonded to the second LED stack 233. The second color filter 267 and the first LED stack 223 may be bonded so as to face each other. For example, a bonding material layer may be formed on the second color filter 267 and the first LED stack 223, respectively, and then bonded to form the second bonding layer 269. The bonding material layer may be a transparent organic layer or a transparent inorganic layer as described above.

[0279] Then, the carrier substrate 251 and the bonding layer 253 are removed, thereby exposing the first reflective electrode 228.

[0280] Reference Figure 31A and Figure 31B The insulating layer 271 is patterned to expose the first LED stack 223 around the first reflective electrode 228, and 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 through which the first conductive semiconductor layer 233a of the second LED stack 233 is exposed. Furthermore, the second LED stack 233 is patterned so that the holes h1 and h2 pass through the second LED stack 233 to expose the second transparent electrode 235. The hole h3 remains to expose the first conductive semiconductor layer 233a of the second LED stack 233.

[0281] Furthermore, 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 at an edge portion of the light emitting device region, thereby exposing the second transparent electrode 235 .

[0282] Reference Figure 32A and Figure 32B The second transparent electrode 235, the first bonding layer 249, and the first color filter 247 are removed through the holes h1 and h2 to expose the third transparent electrode 245. The upper surface of the second transparent electrode 235 is partially exposed in the hole h1.

[0283] In addition, the second transparent electrode 235 , the first bonding layer 249 , and the first color filter 247 are also removed at the edge portion of the light emitting device region to expose the third transparent electrode 245 .

[0284] Reference Figure 33A and Figure 33B The third transparent electrode 245 and the second conductive type semiconductor layer 243 b are patterned to expose the first conductive type semiconductor layer 243 a of the third LED stack 243 through the hole h2 . The hole h1 remains to expose the third transparent electrode 245 .

[0285] In addition, the third transparent electrode 245 and the third LED stack 243 are removed at edge portions of the light emitting device region, thereby exposing the substrate 241. The exposed region of the substrate 241 may be a cutting region for dividing the light emitting devices.

[0286] like Figure 33B As shown in FIG, a hole h1 is formed through the hollow portion of the first reflective electrode 228 and exposes the second transparent electrode 235 and the third transparent electrode 245. A hole h2 passes through both the first LED stack 223 and the second LED stack 233 and exposes the first conductive semiconductor layer 243a by passing through the second conductive semiconductor layer 243b. A hole h3 passes through the first LED stack 223 and exposes the first conductive semiconductor layer 233a of the second LED stack 233.

[0287] Reference Figure 34A and Figure 34B , an upper insulating layer 273 is formed to cover the side surfaces and upper regions of the first LED stack 223, the second LED stack 233, and the third LED stack 243. The upper insulating layer 273 can be formed of a single layer or multiple layers of SiO2, Si3N4, SOG, or the like. Optionally, the upper insulating layer 273 can include a light-reflecting material or a light-blocking material to prevent optical interference between adjacent light-emitting devices. For example, the upper insulating layer 273 can include a distributed Bragg reflector that reflects red, green, and blue light, or a SiO2 layer with a reflective metal layer or a highly reflective organic layer deposited thereon. Alternatively, for example, the upper insulating layer 273 can include black epoxy as a light-blocking material. The light-blocking material can improve the contrast of the image by preventing optical interference between the light-emitting devices. For example, a distributed Bragg reflector can be formed by alternately depositing SiO2 and TiO2 layers.

[0288] Then, the upper insulating layer 273 is patterned using photolithography and etching techniques to form openings in the holes h1, h2, and h3, and further to form openings 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. In addition, the upper insulating layer 273 covers the side walls in the hole h2 while exposing the first conductive semiconductor layer 243a. In addition, the upper insulating layer 273 exposes the first conductive semiconductor layer 233a of the second LED stack 233 in the hole h3. At the same time, the hole h4 passes through the upper insulating layer 273 and the insulating layer 271 to expose the first ohmic electrode 226, and the hole h5 passes through the upper insulating layer 273 to expose the first reflective electrode 228. The hole h5 may be formed as shown in FIG. Figure 34A The diagram shown in FIG has essentially an annular shape.

[0289] Reference Figure 35A and Figure 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.

[0290] 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 connected to the anodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243.

[0291] The first electrode pad 281a is connected to the first ohmic electrode 226 through the hole h4 and is electrically connected to the cathode (e.g., the first conductive semiconductor layer 223a) of the first LED stack 223. Meanwhile, the second electrode pad 281b is electrically connected to the cathode (e.g., the first conductive semiconductor layer 233a) of the second LED stack 233 through the hole h3, and the third electrode pad 281c is electrically connected to the cathode (e.g., the first conductive semiconductor layer 243a) of the third LED stack 243 through the hole h2.

[0292] Meanwhile, the electrode pads 281 a , 281 b , 281 c , and 281 d are electrically separated from each other, so that each of the first LED stack 223 , the second LED stack 233 , and the third LED stack 243 is electrically connected to two electrode pads and is adapted to be independently driven.

[0293] Subsequently, the light emitting device 200 according to the exemplary embodiment is provided by dividing the substrate 241 into light emitting device regions. Figure 35A As shown in FIG, electrode pads 281a, 281b, 281c, and 281d may be provided at four corners of each light emitting device 200. In addition, the electrode pads 281a, 281b, 281c, and 281d may substantially have a ring shape, but are not limited thereto.

[0294] Although the substrate 241 is described as being divided, according to some exemplary embodiments, the substrate 241 may be removed so that the surface of the exposed first conductive type semiconductor layer 243 can be textured. The substrate 241 may be removed after the first LED stack 223 is bonded to the second LED stack 233, or after the electrode pads 281a, 281b, 281c, and 281d are formed.

[0295] According to an exemplary embodiment, the light emitting device includes anodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243 that are electrically connected in common, and their cathodes are independently connected. However, the inventive concept is not limited thereto. For example, the anodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243 may be independently connected to the electrode pad, and their cathodes may be electrically connected in common.

[0296] The light emitting device 200 may include a first LED stack 223, a second LED stack 233, and a third LED stack 243 for emitting red, green, and blue light, and thus may be used as a single pixel in a display device. Figure 20As described above, a display device can be provided by aligning a plurality of light-emitting devices 200 on a circuit board 201. Since the light-emitting device 200 includes a first LED stack 223, a second LED stack 233, and a third LED stack 243, the area of ​​a sub-pixel in a pixel can be increased. In addition, the first LED stack 223, the second LED stack 233, and the third LED stack 243 can be mounted by mounting a single light-emitting device 200, thereby reducing the number of mounting processes.

[0297] As reference Figure 20 As described, the light emitting device 200 mounted on the circuit board 201 may be driven by a passive matrix method or an active matrix method.

[0298] Figure 36 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0299] Reference Figure 36 The light emitting diode stack 1000 includes a supporting 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 (also referred to as a second p-type transparent electrode) 1350, a third p-transparent electrode (also referred to as a third p-type 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. In addition, the first LED stack 1230 may include an ohmic contact portion 1230a for ohmic contact.

[0300] The support substrate 1510 supports the semiconductor stacks 1230, 1330, and 1430. The support substrate 1510 may include a circuit on or in its surface, but the inventive concept is not limited thereto. The support substrate 1510 may include, for example, a Si substrate or a Ge substrate.

[0301] 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 between the n-type semiconductor layer and the p-type semiconductor layer. The active layer has a multi-quantum well structure.

[0302] For example, the first LED stack 1230 may be an inorganic light emitting diode configured to emit red light, the second LED stack 1330 may be an inorganic light emitting diode configured to emit green light, and the third LED stack 1430 may be an inorganic light emitting diode configured to emit blue light. The first LED stack 1230 may include a GaInP base well layer, and each of the second LED stack 1330 and the third LED stack 1430 may include a GaInN base well layer.

[0303] Furthermore, both surfaces of each of the first to third LED stacks 1230, 1330, and 1430 comprise an n-type semiconductor layer and a p-type semiconductor layer, 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 can be formed on the upper surface of the third LED stack 1430 through chemical etching. However, the inventive concept is not limited thereto, and the semiconductor types of the upper and lower surfaces of each LED stack can be selectively arranged.

[0304] The first LED stack 1230 is disposed near the supporting base 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 can be emitted to the outside through the second and third LED stacks 1330 and 1430. Furthermore, 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 can be emitted to the outside through the third LED stack 1430.

[0305] 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.

[0306] The ohmic contact layer 1250a partially contacts the p-type semiconductor layer of the first LED stack 1230. To prevent light from being absorbed 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 total area of ​​the p-type semiconductor layer. The reflective layer 1250b covers the ohmic contact layer 1250a and the insulating layer 1270. Figure 36As shown in FIG, the reflective layer 1250b may substantially cover the entire ohmic contact layer 1250a, but is not limited thereto. Alternatively, the reflective layer 1250b may cover a portion of the ohmic contact layer 1250a.

[0307] Because the reflective layer 1250b covers the insulating layer 1270, an omnidirectional reflector can be formed by the stacked structure of the first LED stack 1230 having a relatively high refractive index and the insulating layer 1270 having a relatively low refractive index and the reflective layer 1250b. The reflective layer 1250b can cover 50% or more of the area of ​​the first LED stack 1230 or most of the first LED stack 1230, thereby improving luminous efficiency.

[0308] The ohmic contact layer 1250a and the reflective layer 1250b may be metal layers that may include Au. The reflective layer 1250b may be formed of a metal having a relatively high reflectivity with respect to the light (e.g., red light) generated from the first LED stack 1230. On the other hand, the reflective layer 1250b may be formed of a metal having a relatively low reflectivity with respect to the light (e.g., green light or blue light) generated from the second LED stack 1330 and the third LED stack 1430 to reduce interference with light that has been generated from the second LED stack 1330 and the third LED stack 1430 and propagates (or travels) toward the support substrate 1510.

[0309] 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 in the opening of the insulating layer 1270.

[0310] The 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, the ohmic contact portion 1230a may protrude from the upper surface of the first LED stack 1230. The ohmic electrode 1290 may be disposed on the ohmic contact portion 1230a.

[0311] 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 may include a metal layer or a conductive oxide layer that is transparent to red and green light.

[0312] 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 may include a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0313] The reflective electrode 1250 , the second p-transparent electrode 1350 , and the third p-transparent electrode 1450 may facilitate current spreading by making ohmic contact with the p-type semiconductor layer of the corresponding LED stack.

[0314] A first color filter 1370 may be interposed between the first LED stack 1230 and the second LED stack 1330. A 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 and reflects light generated from the second LED stack 1330. The second color filter 1470 transmits light generated from the first LED stack 1230 and the second LED stack 1330 and reflects light generated from the third LED stack 1430. In this manner, light generated from the first LED stack 1230 can be emitted to the outside through the second LED stack 1330 and the third LED stack 1430, and light generated from the second LED stack 1330 can be emitted to the outside through the third LED stack 1430. Furthermore, light generated from the second LED stack 1330 may be prevented from entering the first LED stack 1230 , and light generated from the third LED stack 1430 may be prevented from entering the second LED stack 1330 , thereby preventing light loss.

[0315] In some exemplary embodiments, the first color filter 1370 may reflect light generated from the third LED stack 1430 .

[0316] The first color filter 1370 and the second color filter 1470 can be, for example, a low-pass filter that transmits light in a low frequency band (i.e., in a long wavelength band), a band-pass filter that transmits light in a predetermined wavelength band, or a band-stop filter that prevents light in a predetermined wavelength band from passing through it. Specifically, each of the first color filter 1370 and the second color filter 1470 can include a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers (e.g., TiO2 and SiO2) with different refractive indices. In addition, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of the TiO2 layer and the SiO2 layer. The low-pass filter and the band-pass filter can also be formed by alternately stacking insulating layers with different refractive indices with each other.

[0317] The first bonding layer 1530 bonds the first LED stack 1230 to the supporting substrate 1510. Figure 36 As shown in FIG, the reflective electrode 1250 may be adjacent to the first bonding layer 1530. The first bonding layer 1530 may be a light-transmitting layer or an opaque layer.

[0318] The second bonding layer 1550 bonds the second LED stack 1330 to the first LED stack 1230. Figure 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-transmitting spin-on glass.

[0319] The third bonding layer 1570 bonds the third LED stack 1430 to the second LED stack 1330. Figure 36 As shown in FIG, a third bonding layer 1570 may be adjacent to the second LED stack 1330 and the second color filter 1470. For example, a transparent conductive layer may be provided 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.

[0320] Figure 37A 、 Figure 37B 、 Figure 37C 、 Figure 37D and Figure 37E is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0321] Reference Figure 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 may be formed of an AlGaInP-based semiconductor layer and include an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0322] An insulating layer 1270 is formed on the first LED stack 1230 and patterned to form one or more openings. For example, a SiO2 layer is formed on the first LED stack 1230, a photoresist is deposited on the SiO2 layer, and then photolithography is performed and developed to form a photoresist pattern. The SiO2 layer is then patterned using the photoresist pattern as an etching mask to form the insulating layer 1270.

[0323] Then, an ohmic contact layer 1250a is formed in the opening of the insulating layer 1270. The ohmic contact layer 1250a may be 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 may be formed by a lift-off process or the like. Figure 37AAs shown in FIG, the reflective layer 1250b may cover a portion of or the entire ohmic contact layer 1250a. The ohmic contact layer 1250a and the reflective layer 1250b form a reflective electrode 1250.

[0324] The reflective electrode 1250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 1230 , and thus will be referred to as a first p(type) reflective electrode 1250 hereinafter.

[0325] Reference Figure 37B A second LED stack 1330 is grown on a second substrate 1310, and a second p-type transparent electrode 1350 and a first color filter 1370 are formed on the second LED stack 1330. The second LED stack 1330 may be 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 may be grown, and is different from the first substrate 1210. The composition ratio of GaInN used in the second LED stack 1330 may be determined so that the second LED stack 1330 emits green light. The second p-type transparent electrode 1350 forms an ohmic contact with the p-type semiconductor layer of the second LED stack 1330.

[0326] Reference Figure 37C A third LED stack 1430 is grown on a third substrate 1410, and a third p-type transparent electrode 1450 and a second color filter 1470 are formed on the third LED stack 1430. The third LED stack 1430 may be 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 may be grown, and is different from the first substrate 1210. The composition ratio of GaInN used in the third LED stack 1430 may be determined so that the third LED stack 1430 emits blue light. The third p-type transparent electrode 1450 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 1430.

[0327] The first color filter 1370 and the second color filter 1470 may be Figure 36 The described first color filter 1370 and second color filter 1470 are substantially the same, and thus their repeated description will be omitted to avoid redundancy.

[0328] As such, the first LED stack 1230 , the second LED stack 1330 , and the third LED stack 1430 may be grown on different substrates, and their formation order is not limited to a specific order.

[0329] Reference Figure 37D, the first LED stack 1230 is bonded to the support substrate 1510 via the 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 to face the support substrate 1510. The first substrate 1210 is removed from the first LED stack 1230 by chemical etching or the like. As a result, the upper surface of the n-type semiconductor layer of the first LED stack 1230 is exposed.

[0330] Then, an ohmic electrode 1290 is formed in the exposed region of the first LED stack 1230. The ohmic electrode 1290 may be subjected to heat treatment to reduce the ohmic contact resistance of the ohmic electrode 1290. The ohmic electrode 1290 may be formed in each pixel region to correspond to the pixel region.

[0331] Reference Figure 37E The second LED stack 1330 is bonded to the first LED stack 1230 having the ohmic electrode 1290 formed thereon via the second bonding layer 1550. The first color filter 1370 is bonded to the second bonding layer 1550 to face 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 face and bond to the second bonding layer 1550. The second substrate 1310 may be separated from the second LED stack 1330 by a laser lift-off or chemical lift-off process.

[0332] Then, refer to Figure 36 and Figure 37C , the third LED stack 1430 is bonded 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 to face the second LED stack 1330. The third bonding layer 1570 may be pre-set on the second LED stack 1330 so that the second color filter 1470 may face and bond to the third bonding layer 1570. The third substrate 1410 may be separated from the third LED stack 1430 by a laser lift-off or chemical lift-off process. In this manner, Figure 36 As shown, a light emitting diode stack for a display is formed in which the n-type semiconductor layer of the third LED stack 1430 is exposed to the outside.

[0333] By patterning the stack of first to third LED stacks 1230, 1330, and 1430 on a supporting substrate 1510 in pixel units and then connecting the first to third LED stacks to each other via interconnects, a display device according to an exemplary embodiment can be provided. Hereinafter, a display device according to an exemplary embodiment will be described.

[0334] Figure 38is a schematic circuit diagram of a display device according to an exemplary embodiment, Figure 39 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0335] Reference Figure 38 and Figure 39 , the display device according to the exemplary embodiment may operate in a passive matrix manner.

[0336] For example, because Figure 36 The light emitting diode stack for a display includes first to third LED stacks 1230, 1330, and 1430 stacked in a vertical direction, so one pixel may include three light emitting diodes R, G, and B. The first light emitting diode R may correspond to the first LED stack 1230, the second light emitting diode G may correspond to the second LED stack 1330, and the third light emitting diode B may correspond to the third LED stack 1430.

[0337] exist Figure 36 and Figure 39 In the embodiment, a pixel includes first to third light-emitting diodes R, G, and B, each of which corresponds to a sub-pixel. 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 of the first to third light-emitting diodes R, G, and B are connected to different lines (e.g., a scan line). More specifically, 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 their cathodes are respectively connected to the scan lines Vscan1-1, Vscan1-2, and Vscan1-3. In this way, the light-emitting diodes R, G, and B in each pixel can be driven independently.

[0338] Furthermore, each of the light emitting diodes R, G, and B may be driven by pulse width modulation or by varying the magnitude of current, thereby controlling the brightness of each sub-pixel.

[0339] Reference Figure 39 , by Figure 36 The light emitting diode stack 1000 is patterned to form a plurality of pixels, each pixel being connected to the reflective electrode 1250 and the interconnection lines 1710, 1730 and 1750. Figure 38 As shown in FIG, the reflective electrode 1250 may be used as a data line Vdata, and the interconnection lines 1710, 1730, and 1750 may be formed as scan lines.

[0340] The pixels may be arranged in a matrix form, in which the anodes of the light emitting diodes R, G, and B of each pixel are commonly connected to the reflective electrode 1250, and their cathodes are respectively connected to interconnection lines 1710, 1730, and 1750 separated from each other. The interconnection lines 1710, 1730, and 1750 may serve as scan lines Vscan.

[0341] Figure 40 yes Figure 39 An enlarged plan view of one pixel of a display device, Figure 41 It is along Figure 40 A schematic cross-sectional view taken along line AA of FIG. Figure 42 It is along Figure 40 A schematic cross-sectional view taken along line BB of FIG.

[0342] Reference Figure 39 、 Figure 40 、 Figure 41 and Figure 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 ), the second p transparent electrode 1350 (see also Figure 43H ) part, the second LED stack 1330 (see Figure 43J ) of the upper surface, the 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.

[0343] The third LED stack 1430 may have a rough surface 1430a on its upper surface. The rough surface 1430a may be formed over the entire upper surface of the third LED stack 1430, or may be formed as shown in FIG. Figure 41 14. As shown in FIG. 14, LEDs are formed in some areas of the third LED stack 1430.

[0344] The lower insulating layer 1610 may cover the side surfaces of each pixel. The lower insulating layer 1610 may be formed of a light-transmitting 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 propagating toward the side surfaces of the first to third LED stacks 1230, 1330, and 1430. In this case, the lower insulating layer 1610 partially exposes the upper surface of the third LED stack 1430.

[0345] The lower insulating layer 1610 may include an opening 1610a exposing the upper surface of the third LED stack 1430, an opening 1610b exposing the upper surface of the second LED stack 1330, an opening 1610c exposing the ohmic electrode 1290 of the first LED stack 1230 (see FIG. 1 ). Figure 43H ), an opening 1610 d exposing the third p transparent electrode 1450 , an opening 1610 e exposing the second p transparent electrode 1350 , and an opening 1610 f exposing the first p reflective electrode 1250 .

[0346] Interconnection lines 1710 and 1750 may be formed on the support substrate 1510 near the first to third LED stacks 1230, 1330, and 1430, and may be disposed on the lower insulating layer 1610 to be insulated from the first p-reflective electrode 1250. A connecting portion 1770a connects the third p-transparent electrode 1450 to the reflective electrode 1250, and a connecting portion 1770b connects the second p-transparent electrode 1350 to the reflective electrode 1250, such 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.

[0347] The connection portion 1710 a connects the upper surface of the third LED stack 1430 to the interconnection line 1710 , and the connection portion 1750 a connects the ohmic electrode 1290 on the first LED stack 1230 to the interconnection line 1750 .

[0348] An upper insulating layer 1810 may be disposed on the interconnection lines 1710 and 1730 and the lower insulating layer 1610 to cover an upper surface of the third LED stack 1430. The upper insulating layer 1810 may have an opening 1810a partially exposing an upper surface of the second LED stack 1330.

[0349] The interconnection line 1730 may be disposed on the upper insulating layer 1810, and the connection portion 1730a may connect the upper surface of the second LED stack 1330 to the interconnection line 1730. The connection portion 1730a may pass through an upper portion of the interconnection line 1750 and be insulated from the interconnection line 1750 by the upper insulating layer 1810.

[0350] Although the electrodes of each pixel according to the exemplary embodiment of the figure are described as being connected to the data line and the scan line, various embodiments are possible. In addition, although the interconnects 1710 and 1750 are described as being formed on the lower insulating layer 1610 and the interconnect 1730 is formed on the upper insulating layer 1810, the inventive concept is not limited thereto. For example, each of the interconnects 1710, 1730, and 1750 can be formed on the lower insulating layer 1610 and covered by the upper insulating layer 1810, which can have an opening for exposing the interconnect 1730. In this structure, the connecting portion 1730a can connect the upper surface of the second LED stack 1330 to the interconnect 1730 through the opening of the upper insulating layer 1810.

[0351] Alternatively, interconnections 1710, 1730, and 1750 may be formed inside the supporting substrate 1510, and connection portions 1710a, 1730a, and 1750a on the lower insulating layer 1610 may connect the ohmic electrode 1290, the upper surface of the second LED stack 1330, and the upper surface of the third LED stack 1430 to the interconnections 1710, 1730, and 1750.

[0352] Figures 43A to 43K is a diagram showing a method of manufacturing a system according to an exemplary embodiment including Figure 40 A schematic plan view of a pixel display device is provided.

[0353] First, prepare Figure 36 The light emitting diode stack 1000 described in .

[0354] Then, refer to Figure 43A , a rough surface 1430a may be formed on the upper surface of the third LED stack 1430. The rough surface 1430a may be formed on the upper surface of the third LED stack 1430 to correspond to each pixel region. The rough surface 1430a may be formed by chemical etching (e.g., light enhanced chemical etching (PEC) or the like).

[0355] By considering the area of ​​the third LED stack 1430 to be etched in a subsequent process, the rough surface 1430 a may be formed locally in each pixel area, without being limited thereto. Alternatively, the rough surface 1430 a may be formed over the entire upper surface of the third LED stack 1430 .

[0356] Reference Figure 43B , the surrounding area of ​​the third LED stack 1430 in each pixel is removed by etching to expose the third p transparent electrode 1450. Figure 43BAs shown in FIG, the third LED stack 1430 may be maintained to have a rectangular shape or a square shape. The third LED stack 1430 may have a plurality of recesses along its edge.

[0357] Reference Figure 43C , in the area other than one recess of the third LED stack 1430, the upper surface of the second LED stack 1330 is exposed by removing the exposed third p transparent electrode 1450. Therefore, the upper surface of the second LED stack 1330 is exposed around the third LED stack 1430 and in the recesses other than the recess in which the third p transparent electrode 1450 partially remains.

[0358] Reference Figure 43D , in a region other than the other recess of the third LED stack 1430 , the second p transparent electrode 1350 is exposed by removing the exposed second LED stack 1330 .

[0359] Reference Figure 43E In the region other than the other recess of the third LED stack 1430, the ohmic electrode 1290 is exposed along with the upper surface of the first LED stack 1230 by removing the exposed second p-type transparent electrode 1350. In this case, the ohmic electrode 1290 can be exposed in one recess. Thus, the upper surface of the first LED stack 1230 is exposed around the third LED stack 1430, and the upper surface of the ohmic electrode 1290 is exposed in at least one of the recesses formed in the third LED stack 1430.

[0360] Reference Figure 43F The reflective electrode 1250 is exposed by removing the exposed portion of the first LED stack 1230 except for the ohmic electrode 1290 exposed in one recess. The reflective electrode 1250 is exposed around the third LED stack 1430.

[0361] Reference Figure 43G , linear interconnects are formed by patterning the reflective electrode 1250. Here, the support substrate 1510 may be exposed. The reflective electrode 1250 may be arranged in a matrix (see Figure 39 ) pixels arranged in a row are connected to each other.

[0362] Reference Figure 43H , forming a lower insulating layer 1610 (see Figure 41 and Figure 42) 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. In addition, the lower insulating layer 1610 may at least partially cover the upper 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 upper surface of the third LED stack 1430. Alternatively, when the lower insulating layer 1610 includes a distributed Bragg reflector, the lower insulating layer 1610 at least partially exposes the upper surface of the third LED stack 1430 so that light can be emitted to the outside.

[0363] 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 may be formed to expose the reflective electrode 1250.

[0364] Reference Figure 43I , forming interconnects 1710, 1750 and connecting portions 1710a, 1750a, 1770a, and 1770b. These elements can be formed by a lift-off process, etc. Interconnects 1710 and 1750 are insulated from reflective electrode 1250 by lower insulating layer 1610. Connecting portion 1710a electrically connects third LED stack 1430 to interconnect 1710, connecting portion 1750a electrically connects ohmic electrode 1290 to interconnect 1750, thereby electrically connecting first LED stack 1230 to interconnect 1750. Connecting portion 1770a electrically connects third p-type transparent electrode 1450 to first p-type reflective electrode 1250, and connecting portion 1770b electrically connects second p-type transparent electrode 1350 to first p-type reflective electrode 1250.

[0365] Reference Figure 43J , upper insulating layer 1810 (see Figure 41 and Figure 42) covers the interconnection lines 1710 and 1750 and the connection portions 1710a, 1750a, 1770a, and 1770b. The upper insulating layer 1810 may also 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.

[0366] Reference Figure 43K , forming interconnection line 1730 and connection portion 1730a. Interconnection line 1750 and connection portion 1750a can be formed by a lift-off process, etc. Interconnection line 1730 is provided on upper insulating layer 1810 and is insulated from reflective electrode 1250 and interconnections 1710 and 1750. Connection portion 1730a electrically connects second LED stack 1330 to interconnection line 1730. Connection portion 1730a can pass through the upper portion of interconnection line 1750 and be insulated from interconnection line 1750 by upper insulating layer 1810.

[0367] In this way, it can be formed as Figure 40 In addition, as Figure 39 As shown in FIG, a plurality of pixels may be formed on a supporting substrate 1510 and may be connected to each other through a first p-reflective electrode 1250 and interconnection lines 1710, 1730, and 1750, thereby operating in a passive matrix manner.

[0368] Although the above display device has been described as being configured to operate in a passive matrix manner, the inventive concept is not limited thereto. More specifically, the display device according to some exemplary embodiments may be configured to operate in a passive matrix manner. Figure 36 The light emitting diode stacks shown in are fabricated in various ways so as to operate in a passive matrix manner.

[0369] For example, although the interconnection line 1730 is shown as being formed on the upper insulating layer 1810, the interconnection line 1730 may be formed on the lower insulating layer 1610 together with the interconnection lines 1710 and 1750, and the connection portion 1730a may be formed on the upper insulating layer 1810 to connect the second LED stack 1330 to the interconnection line 1730. Alternatively, the interconnection lines 1710, 1730, and 1750 may be provided inside the support substrate 1510.

[0370] Figure 44 is a schematic circuit diagram of a display device according to another exemplary embodiment. The display device according to the illustrated exemplary embodiment may be driven in an active matrix manner.

[0371] Reference Figure 44 According to an exemplary embodiment, the driving circuit includes at least two transistors Tr1 and Tr2 and a capacitor. When the power supply is connected to the selection lines Vrow1 to Vrow3 and the voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diodes. In addition, the corresponding capacitors are charged according to the values ​​of Vdata1 to Vdata3. Because the on-state of the transistor Tr2 can be maintained by the charging voltage of the capacitor, even when the power supplied to the selection line Vrow1 is cut off, the voltage of the capacitor can be maintained and applied to the light-emitting diodes LED1 to LED3. In addition, the current flowing in the light-emitting diodes LED1 to LED3 can change according to the values ​​of Vdata1 to Vdata3. The current can be continuously supplied by the current source Vdd, so that light can be continuously emitted.

[0372] The transistors Tr1 and Tr2 and the capacitor may be formed inside the support substrate 1510. For example, a thin film transistor formed on a silicon substrate may be used for active matrix driving.

[0373] The light emitting diodes LED1 to LED3 may respectively correspond to the first to third LED stacks 1230, 1330, and 1430 stacked in one pixel. Anodes of the first to third LED stacks are connected to the transistor Tr2, and cathodes of the first to third LED stacks are grounded.

[0374] although Figure 44 A circuit for active matrix driving according to an exemplary embodiment is shown, but various other types of circuits may be used. Furthermore, although the anodes of the light-emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2, and the cathodes of the light-emitting diodes LED1 to LED3 are described as being connected to a ground (hereinafter referred to as a ground), the inventive concept is not limited thereto, and the anodes of the light-emitting diodes may be connected to a current source Vdd and the cathodes of the light-emitting diodes may be connected to different transistors.

[0375] Figure 45 15 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 supporting substrate 1511.

[0376] Reference Figure 45 , except that the supporting substrate 1511 is a thin film transistor panel including transistors and capacitors and the reflective electrode is provided in the lower region of the first LED stack, the pixel according to the illustrated exemplary embodiment is similar to the reference Figures 39 to 42 The pixels described are essentially similar.

[0377] The cathode of the third LED stack is connected to the support base 1511 through the connection portion 1711a. Figure 45 As shown in FIG, the cathode of the third LED stack may be grounded by being electrically connected to the support substrate 1511. The cathodes of the second and first LED stacks may also be grounded by being electrically connected to the support substrate 1511 via the connection portions 1731a and 1751a.

[0378] The reflective electrode is connected to the transistor Tr2 inside the supporting substrate 1511 (see Figure 44 The third p-type transparent electrode and the second p-type transparent electrode are also connected to the transistor Tr2 inside the supporting substrate 1511 through the connecting portions 1771b and 1731b (see Figure 44 ).

[0379] In this manner, the first to third LED stacks are connected to each other, thereby forming a Figure 44 The circuit for active matrix driving is shown in .

[0380] although Figure 45 Electrical connections of pixels for active matrix driving according to an exemplary embodiment are shown, but the inventive concept is not limited thereto, and circuits for a display device may be modified in various ways into various circuits for active matrix driving.

[0381] In addition, despite Figure 36 Reflective electrode 1250, second p-type transparent electrode 1350, and third p-type transparent electrode 1450 are described as forming ohmic contact with the corresponding p-type semiconductor layer of each of first LED stack 1230, second LED stack 1330, and third LED stack 1430, and ohmic electrode 1290 forms ohmic contact with the n-type semiconductor layer of first LED stack 1230, but the n-type semiconductor layer of each of second LED stack 1330 and third LED stack 1430 is not provided with a separate ohmic contact layer. When the pixel has a small size of 200 μm or less, even without forming a separate ohmic contact layer in the n-type semiconductor layer, current diffusion is less difficult. However, according to some exemplary embodiments, a transparent electrode layer may be provided on the n-type semiconductor layer of each LED stack to ensure current diffusion.

[0382] Furthermore, although the first to third LED stacks 1230 , 1330 , and 1430 are coupled to each other via the bonding layers 1530 , 1550 , and 1570 , the inventive concept 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.

[0383] According to exemplary embodiments, since multiple pixels can be formed at the wafer level using the light-emitting diode stack 1000 for a display, the need for individual mounting of light-emitting diodes can be avoided. Furthermore, the light-emitting diode stack according to exemplary embodiments has a structure in which first to third LED stacks 1230, 1330, and 1430 are stacked vertically, thereby ensuring an area for sub-pixels within a limited pixel area. Furthermore, the light-emitting diode stack according to exemplary embodiments allows light generated by the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 to pass therethrough and be emitted to the outside, thereby reducing light loss.

[0384] Figure 46 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0385] Reference Figure 46 The light emitting diode stack 2000 includes a supporting 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 (also referred to as a second p-type transparent electrode) 2350, a third p-transparent electrode (also referred to as a third p-type transparent electrode) 2450, an insulating layer 2270, a first bonding layer 2530, a second bonding layer 2550, and a third bonding layer 2570. In addition, the first LED stack 2230 may include an ohmic contact portion 2230a for ohmic contact.

[0386] In general, light can be generated from the first LED stack due to light emitted from the second LED stack, and light can be generated from the second LED stack due to light emitted from the third LED stack. In this manner, color filters can be interposed between the second LED stack and the first LED stack, and between the third LED stack and the second LED stack.

[0387] However, although the color filter can prevent interference of light, the step of forming the color filter increases manufacturing complexity. The display device according to the exemplary embodiment can suppress the generation of secondary light between LED stacks without arranging a color filter between the LED stacks.

[0388] Thus, in some exemplary embodiments, light interference between LED stacks can be reduced by controlling the bandgap of each LED stack, as will be described in greater detail below.

[0389] The support substrate 2510 supports the semiconductor stacks 2230, 2330, and 2430. The support substrate 2510 may include a circuit on its surface or therein, but the inventive concept is not limited thereto. The 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.

[0390] 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 between the n-type semiconductor layer and the p-type semiconductor layer. The active layer may have a multi-quantum well structure.

[0391] The light L1 generated from the first LED stack 2230 has a longer wavelength than the light L2 generated from the second LED stack 2330 , and the light L2 generated from the second LED stack 2330 has a longer wavelength than the light L3 generated from the third LED stack 2430 .

[0392] 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 base well layer, and each of the second and third LED stacks 2330 and 2430 may include a GaInN base well layer.

[0393] although Figure 46 The light emitting diode stack 2000 is shown as including three LED stacks 2230, 2330, and 2430, but the inventive concept is not limited to a specific number of LED stacks one above the other. For example, an LED stack for emitting yellow light may be further added between the first LED stack 2230 and the second LED stack 2330.

[0394] Both surfaces of each of the first to third LED stacks 2230, 2330, and 2430 are an n-type semiconductor layer and a p-type semiconductor layer, respectively. Figure 46 , each of the first to third LED stacks 2230, 2330, and 2430 is described 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 rough surface can be formed on the upper surface of the third LED stack 2430 by chemical etching or the like. However, the inventive concept is not limited thereto, and the semiconductor types of the upper and lower surfaces of each LED stack can be selectively formed.

[0395] The first LED stack 2230 is disposed near the support base 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 wavelength of light emitted by the first LED stack 2230 is longer than the wavelengths of light emitted by the second and third LED stacks 2330, 2430, light L1 generated by the first LED stack 2230 can be emitted to the outside through the second and third LED stacks 2330, 2430. Furthermore, because the wavelength of light emitted by the second LED stack 2330 is longer than the wavelength of light emitted by the third LED stack 2430, light L2 generated by the second LED stack 2330 can be emitted to the outside through the third LED stack 2430. Light L3 generated in the third LED stack 2430 is emitted directly to the outside from the third LED stack 2430.

[0396] In an exemplary embodiment, the n-type semiconductor layer of the first LED stack 2230 may have a band gap that is wider than the band gap of the active layer of the first LED stack 2230 and narrower than the band gap of the active layer of the second LED stack 2330. Therefore, a portion of the light generated from the second LED stack 2330 may 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. As such, the intensity of the light generated in the active layer of the first LED stack 2230 may be reduced by the light generated from the second LED stack 2330.

[0397] Furthermore, the n-type semiconductor layer of the second LED stack 2330 has a band gap that is wider than the band gap of the active layer of each of the first LED stack 2230 and the second LED stack 2330 and narrower than the band gap of the active layer of the third LED stack 2430. Therefore, a portion of the light generated from the third LED stack 2430 may 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. As such, the intensity of the light generated in the second LED stack 2330 or the first LED stack 2230 may be reduced due to the light generated from the third LED stack 2430.

[0398] The p-type semiconductor layer and the n-type semiconductor layer of the third LED stack 2430 have wider band gaps than the active layers of the first and second LED stacks 2230 and 2330 , thereby transmitting light generated from the first and second LED stacks 2230 and 2330 therethrough.

[0399] According to exemplary embodiments, by adjusting the band gap of the n-type semiconductor layer or the p-type semiconductor layer of the first LED stack 2230 and the second LED stack 2330, it is possible to reduce interference of light between the LED stacks 2230, 2330, and 2430, thereby eliminating the need for additional components such as color filters. For example, the intensity of light generated from the second LED stack 2330 and emitted to the outside may be approximately 10 times or greater than the intensity of light generated from the first LED stack 2230 due to the light generated from the second LED stack 2330. Similarly, the intensity of light generated from the third LED stack 2430 and emitted to the outside may be approximately 10 times or greater than the intensity of light generated from the second LED stack 2330 due to the light generated from the third LED stack 2430. In this case, the intensity of light generated from the third LED stack 2430 and emitted to the outside may be approximately 10 times or greater than the intensity of light generated from the first LED stack 2230 due to the light generated from the third LED stack 2430. Therefore, it is possible to realize a display device that is free from light pollution caused by interference of light.

[0400] 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.

[0401] The ohmic contact layer 2250a partially contacts the p-type semiconductor layer of the first LED stack 2230. To prevent the ohmic contact layer 2250a from absorbing light, the area where the ohmic contact layer 2250a contacts the p-type semiconductor layer may not exceed approximately 50% of the total area of ​​the p-type semiconductor layer. The reflective layer 2250b covers the ohmic contact layer 2250a and the insulating layer 2270. Figure 46 As shown in FIG, the reflective layer 2250b may substantially cover the entire ohmic contact layer 2250a, but is not limited thereto. Alternatively, the reflective layer 2250b may cover a portion of the ohmic contact layer 2250a.

[0402] Because the reflective layer 2250b covers the insulating layer 2270, an omnidirectional reflector can be formed by the stacked structure of the first LED stack 2230 having a relatively high refractive index and 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.

[0403] The ohmic contact layer 2250a and the reflective layer 2250b may be formed of a metal layer that may include Au. The reflective layer 2250b may include a metal having a relatively high reflectivity with respect to light (e.g., red light) generated from the first LED stack 2230. On the other hand, the reflective layer 2250b may include a metal having a relatively low reflectivity with respect to light (e.g., green light or blue light) generated from the second LED stack 2330 and the third LED stack 2430 to reduce interference with light generated from the second stack 2330 and the third stack 2430 and propagating toward the support substrate 2510.

[0404] 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 in the opening of the insulating layer 2270.

[0405] The 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, the ohmic contact portion 2230a may protrude from the upper surface of the first LED stack 2230. The ohmic electrode 2290 may be disposed on the ohmic contact portion 2230a.

[0406] 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 may be formed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0407] 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 may be formed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0408] The reflective electrode 2250 , the second p transparent electrode 2350 , and the third p transparent electrode 2450 may facilitate current spreading by making ohmic contact with the p-type semiconductor layer of the corresponding LED stack.

[0409] The first bonding layer 2530 bonds the first LED stack 2230 to the support substrate 2510. Figure 46 As shown in FIG, the reflective electrode 2250 may be adjacent to the first bonding layer 2530. The first bonding layer 2530 may be a light-transmitting layer or an opaque layer.

[0410] The second bonding layer 2550 bonds the second LED stack 2330 to the first LED stack 2230. Figure 46As shown in FIG, 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 a light-transmitting bonding material (e.g., a light-transmitting organic bonding agent or a light-transmitting spin-on glass). Examples of light-transmitting organic bonding agents may include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc. In addition, the second LED stack 2330 may be bonded to the first LED stack 2230 by plasma bonding or the like.

[0411] The third bonding layer 2570 bonds the third LED stack 2430 to the second LED stack 2330. Figure 46 As shown in FIG, the third bonding layer 2570 may be adjacent to the second LED stack 2330 and the third p-type transparent electrode 2450. However, the inventive concept is not limited thereto. For example, a transparent conductive layer may be provided 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.

[0412] Each of the second bonding layer 2550 and the third bonding layer 2570 may transmit light generated from the third LED stack 2430 and light generated from the second LED stack 2330 .

[0413] Figures 47A to 47E is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0414] Reference Figure 47A A 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 exemplary embodiments, the n-type semiconductor layer may have an energy bandgap capable of absorbing light generated by the second LED stack 2330, and the p-type semiconductor layer may have an energy bandgap capable of absorbing light generated by the second LED stack 2330.

[0415] An insulating layer 2270 is formed on the first LED stack 2230 and patterned to form one or more openings therein. For example, a SiO2 layer is formed on the first LED stack 2230, a photoresist is deposited on the SiO2 layer, and then photolithography is performed and developed to form a photoresist pattern. The SiO2 layer is then patterned using the photoresist pattern as an etching mask, thereby forming the insulating layer 2270 having the openings.

[0416] Then, an ohmic contact layer 2250a is formed in the opening of the insulating layer 2270. The ohmic contact layer 2250a can be formed by a lift-off process, etc. 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 can be formed by a lift-off process, etc. The reflective layer 2250b can cover part or all of the ohmic contact layer 2250a. The ohmic contact layer 2250a and the reflective layer 2250b form the reflective electrode 2250.

[0417] The reflective electrode 2250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 2230 , and thus will be referred to as a first p(type) reflective electrode 2250 hereinafter.

[0418] Reference Figure 47B A second LED stack 2330 is grown on the second substrate 2310, and a second p-type transparent electrode 2350 is formed on the second LED stack 2330. The second LED stack 2330 may be 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 used in the second LED stack 2330 may be determined so that the second LED stack 2330 emits green light. The second p-type transparent electrode 2350 forms an 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 exemplary embodiments, the n-type semiconductor layer of the second LED stack 2330 may have an energy bandgap capable of absorbing light generated by the third LED stack 2430, and the p-type semiconductor layer of the second LED stack 2330 may have an energy bandgap capable of absorbing light generated by the third LED stack 2430.

[0419] Reference Figure 47CA third LED stack 2430 is grown on a third substrate 2410, and a third p-type transparent electrode 2450 is formed on the third LED stack 2430. The third LED stack 2430 may be 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 may be grown, and is different from the first substrate 2210. The composition ratio of GaInN used in the third LED stack 2430 may be determined so that the third LED stack 2430 emits blue light. The third p-type transparent electrode 2450 forms an ohmic contact with the p-type semiconductor layer of the third LED stack 2430.

[0420] As such, the first LED stack 2230 , the second LED stack 2330 , and the third LED stack 2430 are grown on different substrates, and their formation order is not limited to a specific order.

[0421] Reference Figure 47D , the first LED stack 2230 is bonded to the support substrate 2510 via the 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 so as to face the support substrate 2510. The first substrate 2210 is removed from the first LED stack 2230 by chemical etching or the like. As a result, the upper surface of the n-type semiconductor layer of the first LED stack 2230 is exposed.

[0422] Then, an ohmic electrode 2290 is formed in the exposed region of the first LED stack 2230. The ohmic electrode 2290 may be subjected to heat treatment to reduce the ohmic contact resistance of the ohmic electrode 2290. The ohmic electrode 2290 may be formed in each pixel region to correspond to the pixel region.

[0423] Reference Figure 47E The second LED stack 2330 is bonded to the first LED stack 2230 on which the ohmic electrode 2290 is formed via the second bonding layer 2550. The second p transparent electrode 2350 is bonded to the second bonding layer 2550 to face the first LED stack 2230. The second bonding layer 2550 may be pre-formed on the first LED stack 2230 so that the second p transparent electrode 2350 can face and be bonded to the second bonding layer 2550. The second substrate 2310 may be separated from the second LED stack 2330 by a laser lift-off process or a chemical lift-off process.

[0424] Then, refer to Figure 46 and Figure 47C, the third LED stack 2430 is bonded 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 to face 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 may face and be bonded to the third bonding layer 2570. The third substrate 2410 may be separated from the third LED stack 2430 by a laser lift-off process or a chemical lift-off process. In this way, a structure such as Figure 46 , a light emitting diode stack for a display is shown in which the n-type semiconductor layer of the third LED stack 2430 is exposed to the outside.

[0425] A display device can be formed by patterning the stack of first to third LED stacks 2230, 2330, and 2430 disposed on a supporting substrate 2510 in pixel units, and then connecting the first to third LED stacks 2230, 2330, and 2430 to each other via interconnects. However, the inventive concept is not limited thereto. For example, a display device can be manufactured by dividing the stack of first to third LED stacks 2230, 2330, and 2430 into independent units and transferring the first to third LED stacks 2230, 2330, and 2430 to another supporting substrate such as a printed circuit board.

[0426] Figure 48 is a schematic circuit diagram of a display device according to an exemplary embodiment. Figure 49 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0427] Reference Figure 48 and Figure 49 , the display device according to the exemplary embodiment may be implemented to be driven in a passive matrix manner.

[0428] Figure 46 The light emitting diode stack for a display shown in FIG has a structure including first to third LED stacks 2230, 2330, and 2430 stacked in a vertical direction. Since one pixel includes three light emitting diodes R, G, and B, the first light emitting diode R may correspond to the first LED stack 2230, the second light emitting diode G may correspond to the second LED stack 2330, and the third light emitting diode B may correspond to the third LED stack 2430.

[0429] Reference Figure 48 and Figure 49, a pixel includes first to third light-emitting diodes R, G, and B, each of which can 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 of the first to third light-emitting diodes R, G, and B 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 of the first to third light-emitting diodes R, G, and B 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.

[0430] In addition, each of the light emitting diodes R, G, and B may be driven by pulse width modulation or by varying the magnitude of current to control the brightness of each sub-pixel.

[0431] Reference Figure 49 , by Figure 46 The stack of pieces is patterned to form a plurality of pixels, and each pixel is connected to the reflective electrode 2250 and the interconnection lines 2710, 2730 and 2750. Figure 48 As shown in FIG, the reflective electrode 2250 may be used as a data line Vdata, and the interconnection lines 2710, 2730, and 2750 may be formed as scan lines.

[0432] The pixels may be arranged in a matrix form, in which the anodes of the light-emitting diodes R, G, and B of each pixel are commonly connected to the reflective electrode 2250, and the cathodes of the light-emitting diodes R, G, and B of each pixel are connected to interconnection lines 2710, 2730, and 2750 separated from each other. Here, the interconnection lines 2710, 2730, and 2750 may serve as scan lines Vscan.

[0433] Figure 50 yes Figure 49 An enlarged plan view of a pixel of a display device. Figure 51 It is along Figure 50 A schematic cross-sectional view taken along line AA of FIG. Figure 52 It is along Figure 50 A schematic cross-sectional view taken along line BB of FIG.

[0434] Reference 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 ), part 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 ), part 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.

[0435] The third LED stack 2430 may have a rough surface 2430 a on its upper surface. The rough surface 2430 a may be formed over the entire upper surface of the third LED stack 2430 or may be formed in some regions of the third LED stack 2430 .

[0436] The lower insulating layer 2610 may cover the side surfaces of each pixel. The lower insulating layer 2610 may be formed of a light-transmitting material such as SiO2. In this case, the lower insulating layer 2610 may substantially cover 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 propagating 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 black insulating layer that absorbs light. In addition, an electrically floating metal reflective layer may be further formed on the lower insulating layer 2610 to emit light emitted through the side surfaces of the first to third LED stacks 2230, 2330, and 2430.

[0437] The lower insulating layer 2610 may include: an opening 2610a exposing the upper surface of the third LED stack 2430; an opening 2610b exposing the upper surface of the second LED stack 2330; an opening 2610c (see Figure 53H ), exposing the ohmic electrode 2290 of the first LED stack 2230; opening 2610d, exposing the third p transparent electrode 2450; opening 2610e, exposing the second p transparent electrode 2350; opening 2610f, exposing the first p reflective electrode 2250.

[0438] Interconnection lines 2710 and 2750 may be formed on the supporting substrate 2510 near the first to third LED stacks 2230, 2330, and 2430, and may be disposed on the lower insulating layer 2610 to be insulated from the first p reflective electrode 2250. A connecting portion 2770a connects the third p transparent electrode 2450 to the reflective electrode 2250, and a connecting portion 2770b connects the second p transparent electrode 2350 to the reflective electrode 2250, such 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.

[0439] The connection portion 2710 a connects the upper surface of the third LED stack 2430 to the interconnection line 2710 , and the connection portion 2750 a connects the ohmic electrode 2290 on the first LED stack 2230 to the interconnection line 2750 .

[0440] An upper insulating layer 2810 may be disposed on the interconnection lines 2710 and 2730 and the lower insulating layer 2610 to cover the upper surface of the third LED stack 2430. The upper insulating layer 2810 may have an opening 2810a partially exposing the upper surface of the second LED stack 2330.

[0441] The interconnection line 2730 may be disposed on the upper insulating layer 2810, and the connection portion 2730a may connect the upper surface of the second LED stack 2330 to the interconnection line 2730. The connection portion 2730a may pass through the upper portion of the interconnection line 2750 and be insulated from the interconnection line 2750 by the upper insulating layer 2810.

[0442] Although the electrodes of each pixel are described as being connected to a data line and a scan line, the inventive concept is not limited thereto. Furthermore, although the interconnects 2710 and 2750 are described as being formed on the lower insulating layer 2610, and the interconnect 2730 is described as being formed on the upper insulating layer 2810, the inventive concept is not limited thereto. For example, all of the interconnects 2710, 2730, and 2750 may be formed on the lower insulating layer 2610 and may be covered by the upper insulating layer 2810, which may have an opening that exposes the interconnect 2730. In this manner, the connecting portion 2730a may connect the upper surface of the second LED stack 2330 to the interconnect 2730 through the opening of the upper insulating layer 2810.

[0443] Optionally, interconnection lines 2710, 2730 and 2750 can be formed inside the supporting substrate 2510, and connection portions 2710a, 2730a and 2750a on the lower insulating layer 2610 can connect the ohmic electrode 2290, the upper surface of the second LED stack 2330 and the upper surface of the third LED stack 2430 to the interconnection lines 2710, 2730 and 2750.

[0444] According to an exemplary embodiment, light L1 generated from the first LED stack 2230 is emitted to the outside through the second LED stack 2330 and the third LED stack 2430, and light L2 generated from the second LED stack 2330 is emitted to the outside through the third LED stack 2430. In addition, 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 due to light L3, and secondary light may also be generated from the first LED stack 2230 due to light L2. However, this secondary light may have low intensity.

[0445] Figures 53A to 53K is a schematic plan view illustrating a method of manufacturing a display device according to an exemplary embodiment. Figure 50 The following description is given for the pixels.

[0446] First, prepare Figure 46 The light emitting diode stack 2000 described in .

[0447] Reference Figure 53A , a rough surface 2430a may be formed on the upper surface of the third LED stack 2430. The rough surface 2430a may be formed on the upper surface of the third LED stack 2430 to correspond to each pixel region. The rough surface 2430a may be formed by chemical etching (e.g., light enhanced chemical etching (PEC)) or the like.

[0448] By considering the area of ​​the third LED stack 2430 to be etched in a subsequent process, the rough surface 2430 a may be partially formed in each pixel area, but is not limited thereto. Alternatively, the rough surface 2430 a may be formed over the entire upper surface of the third LED stack 2430 .

[0449] Reference Figure 53B , the surrounding area of ​​the third LED stack 2430 in each pixel is removed by etching to expose the third p transparent electrode 2450. Figure 53B As shown in , the third LED stack 2430 may be maintained to have a rectangular shape or a square shape. The third LED stack 2430 may have a plurality of recesses formed along edges thereof.

[0450] Reference Figure 53C, the upper surface of the second LED stack 2330 is exposed by removing the exposed third p transparent electrode 2450 in the region except for one recess. Therefore, the upper surface of the second LED stack 2330 is exposed around the third LED stack 2430 and in the recesses except for the recess where the third p transparent electrode 2450 is partially retained.

[0451] Reference Figure 53D , the second p transparent electrode 2350 is exposed by removing the exposed second LED stack 2330 exposed in a region other than one recess.

[0452] Reference Figure 53E By removing the exposed second p-type transparent electrode 2350 in the region except for one recess, the ohmic electrode 2290 is exposed along with the upper surface of the first LED stack 2230. Here, the ohmic electrode 2290 can be exposed in one recess. Thus, the upper surface of the first LED stack 2230 is exposed around the third LED stack 2430, and the upper surface of the ohmic electrode 2290 is exposed in at least one of the recesses formed in the third LED stack 2430.

[0453] Reference Figure 53F The reflective electrode 2250 is exposed by removing the exposed portion of the first LED stack 2230 in the region except for one recess. As such, the reflective electrode 2250 is exposed around the third LED stack 2430.

[0454] Reference Figure 53G , linear interconnects are formed by patterning the reflective electrode 2250. Here, the support substrate 2510 may be exposed. The reflective electrode 2250 may enable the pixels arranged in a matrix (see Figure 49 ) are connected to each other in a row.

[0455] Reference Figure 53H , forming a lower insulating layer 2610 (see Figure 51 and Figure 52) to cover the pixels. The lower insulating layer 2610 covers the side surfaces of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430, as well as the reflective electrode 2250. In addition, the lower insulating layer 2610 may partially cover the upper surface of the third LED stack 2430. If the lower insulating layer 2610 is a transparent layer such as a SiO2 layer, the lower insulating layer 2610 may substantially cover the entire upper 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 may partially expose the upper surface of the third LED stack 2430 to enable light to be emitted to the outside.

[0456] 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-type transparent electrode 2450, an opening 2610e exposing the second p-type transparent electrode 2350, and an opening 2610f exposing the reflective electrode 2250. The opening 2610f exposing the reflective electrode 2250 may be formed in a single opening or in a plurality.

[0457] Reference Figure 53I Interconnections 2710 and 2750 and connecting portions 2710a, 2750a, 2770a, and 2770b are formed by a lift-off process or the like. Interconnections 2710 and 2750 are insulated from reflective electrode 2250 by lower insulating layer 2610. Connecting portion 2710a electrically connects third LED stack 2430 to interconnecting portion 2710, while connecting portion 2750a electrically connects ohmic electrode 2290 to interconnecting portion 2750, thereby electrically connecting first LED stack 2230 to interconnecting portion 2750. Connecting portion 2770a electrically connects third p-transparent electrode 2450 to first p-reflective electrode 2250, while connecting portion 2770b electrically connects second p-transparent electrode 2350 to first p-reflective electrode 2250.

[0458] Reference Figure 53J , upper insulating layer 2810 (see Figure 51 and Figure 52) covers the interconnect lines 2710, 2750 and the connecting portions 2710a, 2750a, 2770a and 2770b. The upper insulating layer 2810 may also substantially cover 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 may be formed of, for example, silicon oxide or silicon nitride, and may include a distributed Bragg reflector. When the upper insulating layer 2810 includes a distributed Bragg reflector, the upper insulating layer 2810 may expose at least a portion of the upper surface of the third LED stack 2430 to enable light to be emitted to the outside.

[0459] Reference Figure 53K , forming interconnection line 2730 and connection portion 2730a. Interconnection line 2750 and connection portion 2750a can be formed by a lift-off process, etc. Interconnection line 2730 is provided on upper insulating layer 2810 and is insulated from reflective electrode 2250 and interconnections 2710 and 2750. Connection portion 2730a electrically connects second LED stack 2330 to interconnection line 2730. Connection portion 2730a can pass through the upper portion of interconnection line 2750 and be insulated from interconnection line 2750 by upper insulating layer 2810.

[0460] In this way, it can form Figure 50 In addition, as shown in the pixel area Figure 49 As shown in FIG, a plurality of pixels may be formed on a supporting substrate 2510 and connected to each other through a first p reflective electrode 2250 and interconnection lines 2710, 2730, and 2750, thereby operating in a passive matrix manner.

[0461] Although the above describes a method for manufacturing a display device that can operate in a passive matrix manner, the inventive concept is not limited thereto. More specifically, a method for manufacturing a display device that can operate in a passive matrix manner can be used. Figure 46 The light emitting diode stack shown in FIG. 1 is used to manufacture a display device according to an exemplary embodiment in various manners so as to operate in a passive matrix manner.

[0462] For example, although the interconnection line 2730 is described as being formed on the upper insulating layer 2810, the interconnection line 2730 may be formed on the lower insulating layer 2610 together with the interconnection lines 2710 and 2750, and the connection portion 2730a may be formed on the upper insulating layer 2810 to connect the second LED stack 2330 to the interconnection line 2730. Alternatively, the interconnection lines 2710, 2730, and 2750 may be disposed inside the support substrate 2510.

[0463] Figure 54 is a schematic circuit diagram of a display device according to another exemplary embodiment. Figure 54The circuit diagram relates to a display device driven in an active matrix manner.

[0464] Reference Figure 54 According to an exemplary embodiment, the driving circuit includes at least two transistors Tr1 and Tr2 and a capacitor. When the power supply is connected to the selection lines Vrow1 to Vrow3 and the voltage is applied to the data lines Vdata1 to Vdata3, the voltage is applied to the corresponding light-emitting diodes. In addition, the corresponding capacitors are charged according to the values ​​of Vdata1 to Vdata3. Since the on-state of the transistor Tr2 can be maintained by the charging voltage of the capacitor, the voltage of the capacitor can be maintained and applied to the light-emitting diodes LED1 to LED3 even when the power supplied to the selection line Vrow1 is cut off. In addition, the current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the values ​​of Vdata1 to Vdata3. The current can be continuously supplied by the current source Vdd, so that the light can be continuously emitted.

[0465] The transistors Tr1 and Tr2 and the capacitor may be formed inside the support substrate 2510. For example, a thin film transistor formed on a silicon substrate may be used for active matrix driving.

[0466] Here, the light emitting diodes LED1 to LED3 may respectively correspond to the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 stacked in one pixel. The anodes of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 are connected to the transistor Tr2, and their cathodes are grounded.

[0467] Although Figure 54 A circuit for active matrix driving according to an exemplary embodiment is shown, but other types of circuits may be used variously. Furthermore, although the anodes of the light-emitting diodes LED1 to LED3 are described as being connected to different transistors Tr2 and their cathodes are described as being grounded, in some exemplary embodiments, the anodes of the light-emitting diodes may be connected to a current source Vdd, and their cathodes may be connected to different transistors.

[0468] Figure 55 is a schematic plan view of a pixel of a display device according to another exemplary embodiment. Hereinafter, the following description will be given with reference to one pixel among a plurality of pixels arranged on a supporting substrate 2511.

[0469] Reference Figure 55, except that the supporting substrate 2511 is a thin film transistor panel including transistors and capacitors and the reflective electrode 2250 is provided in the lower region of the first LED stack 2230, the pixel according to the exemplary embodiment is substantially similar to that in the reference numerals. Figures 49 to 52 Described pixels.

[0470] The cathode of the third LED stack 2430 is connected to the support base 2511 through the connecting portion 2711a. Figure 55 As shown in FIG, the cathode of the third LED stack 2430 may be grounded by being electrically connected to the support substrate 2511. The cathodes of the second LED stack 2330 and the first LED stack 2230 may also be grounded by being electrically connected to the support substrate 2511 via the connection portions 2731a and 2751a.

[0471] The reflective electrode is connected to the transistor Tr2 (see Figure 54 The third p-type transparent electrode and the second p-type transparent electrode are also connected to the transistor Tr2 inside the supporting substrate 2511 through the connecting portions 2771a and 2731b (see Figure 54 ).

[0472] In this manner, the first to third LED stacks are connected to each other, thereby forming a Figure 54 The circuit for active matrix driving is shown in .

[0473] Although Figure 55 Pixels with electrical connections for active matrix driving according to exemplary embodiments are shown, but the inventive concept is not limited thereto, and circuits for a display device may be modified in various ways into various circuits for active matrix driving.

[0474] also, Figure 46 The reflective electrode 2250, the second p-type transparent electrode 2350, and the third p-type transparent electrode 2450 are described as forming an ohmic contact with the p-type semiconductor layer of each of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430. The ohmic electrode 2290 is described as forming an ohmic contact with the n-type semiconductor layer of the first LED stack 2230. The n-type semiconductor layer of each of the second LED stack 2330 and the third LED stack 2430 is not provided with a separate ohmic contact layer. Although current diffusion is less difficult when the pixel has a small size of 200 μm or less even without forming a separate ohmic contact layer in the n-type semiconductor layer, according to some exemplary embodiments, a transparent electrode layer may be provided on the n-type semiconductor layer of each of the LED stacks to ensure current diffusion.

[0475] In addition, although Figure 46It is shown that the first LED stack 2230, the second LED stack 2330 and the third LED stack 2430 are combined with each other via a bonding layer, but the inventive concept is not limited to this. The first LED stack 2230, the second LED stack 2330 and the third LED stack 2430 can be connected to each other in various orders and using various structures.

[0476] According to exemplary embodiments, since multiple pixels can be formed at the wafer level using the light-emitting diode stack 2000 for a display, the need to separately mount light-emitting diodes can be avoided. Furthermore, the light-emitting diode stack according to exemplary embodiments has a structure in which the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 are stacked vertically, thereby ensuring an area for sub-pixels within a limited pixel area. Furthermore, the light-emitting diode stack according to exemplary embodiments enables light generated by the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 to pass therethrough and be emitted to the outside, thereby reducing light loss.

[0477] Figure 56 is a schematic plan view of a display device according to an exemplary embodiment, Figure 57 is a schematic cross-sectional view of a light emitting diode pixel for a display device according to an exemplary embodiment.

[0478] Reference Figure 56 and Figure 57 The display device includes a circuit board 3510 and a plurality of pixels 3000. Each pixel 3000 includes a substrate 3210 and a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B disposed on the substrate 3210.

[0479] Circuit board 3510 may include passive circuits or active circuits. Passive circuits may include, for example, data lines and scan lines. Active circuits may include, for example, transistors and capacitors. Circuit board 3510 may have circuits on its surface or within its interior. Circuit board 3510 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

[0480] The substrate 3210 supports the first subpixel R, the second subpixel G, and the third subpixel B. The substrate 3210 is continuous with the plurality of pixels 3000 and electrically connects the subpixels R, G, and B to the circuit board 3510. For example, the substrate 3210 may be a GaAs substrate.

[0481] 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 LED stack 3230, the second LED stack 3330, and the third LED stack 3430 can be driven independently.

[0482] The first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 are stacked to overlap each other in the vertical direction. Figure 57 As shown in FIG, the second LED stack 3330 may be disposed in a portion of the first LED stack 3230. For example, the second LED stack 3330 may be disposed toward one side on the first LED stack 3230. The third LED stack 3430 may be disposed in a portion of the second LED stack 3330. For example, the third LED stack 3430 may be disposed toward one side on the second LED stack 3330. Although Figure 57 The third LED stack 3430 is shown to be disposed toward the right, but the inventive concept is not limited thereto. Alternatively, the third LED stack 3430 may be disposed toward the left of the second LED stack 3330 .

[0483] The light R generated from the first LED stack 3230 may be emitted through an area not covered by the second LED stack 3330, and the light G generated from the second LED stack 3330 may be emitted through an area not covered by the third LED stack 3430. More specifically, the light generated from the first LED stack 3230 may be emitted to the outside without passing through the second LED stack 3330 and the third LED stack 3430, and the light generated from the second LED stack 3330 may be emitted to the outside without passing through the third LED stack 3430.

[0484] The area of ​​the first LED stack 3230 through which light R is emitted, the area of ​​the second LED stack 3330 through which light G is emitted, and the area of ​​the third LED stack 3430 can have different areas, and the intensity of light emitted from each of the LED stacks 3230, 3330 and 3430 can be adjusted by adjusting their areas.

[0485] However, the inventive concept is not limited thereto. Alternatively, the light generated from the first LED stack 3230 may be 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 the light generated from the second LED stack 3330 may be emitted to the outside after passing through the third LED stack 3430.

[0486] 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 disposed between the first conductivity type (e.g., n-type) semiconductor layer and the second conductivity type (e.g., p-type) semiconductor layer. The active layer may have a multi-quantum well structure. The first LED stack 3230, the second LED stack 3330, and the third LED stack 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. To this end, the first LED stack 3230 may include an AlGaInP base well layer, the second LED stack 3330 may include an AlGaInP base well layer or an AlGaInN base well layer, and the third LED stack 3430 may include an AlGaInN base well layer. However, the inventive concept is not limited thereto. The wavelength of light generated by the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may be varied. 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 may emit green light, blue light, and red light, respectively.

[0487] In addition, a distributed Bragg reflector may be placed between the substrate 3210 and the first LED stack 3230 to prevent light generated from the first LED stack 3230 from being lost due to absorption by the substrate 3210. For example, a distributed Bragg reflector formed by alternately stacking AlAs semiconductor layers and AlGaAs semiconductor layers one on top of another may be placed therebetween.

[0488] Figure 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0489] Reference Figure 58 The display device according to the exemplary embodiment may be driven in an active matrix manner. As such, the circuit board may include an active circuit.

[0490] For example, the driving circuit may include at least two transistors Tr1, Tr2 and a capacitor. When the power supply is connected to the selection 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 diodes. In addition, the corresponding capacitors are charged according to the values ​​of Vdata1 to Vdata3. Since the on-state of the transistor Tr2 can be maintained by the charging voltage of the capacitor, the voltage of the capacitor can be maintained and applied to the light-emitting diodes LED1 to LED3 even when the power supplied to the selection line Vrow1 is cut off. In addition, the current flowing in the light-emitting diodes LED1 to LED3 can be changed according to the values ​​of Vdata1 to Vdata3. The current can be continuously supplied by the current source Vdd, and therefore, the light can be continuously emitted.

[0491] Transistors Tr1 and Tr2 and a capacitor may be formed within the support substrate 3510. Here, light-emitting diodes LED1 to LED3 may correspond to a first LED stack 3230, a second LED stack 3330, and a third LED stack 3430, respectively, stacked in one pixel. The anodes of the first, second, and third LED stacks 3230, 3330, and 3430 are connected to the transistor Tr2, while their cathodes are grounded. The cathodes of the first, second, and third LED stacks 3230, 3330, and 3430 may be commonly grounded, for example.

[0492] Although Figure 58 A circuit for active matrix driving according to an exemplary embodiment is shown, but other types of circuits may also 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 their cathodes are described as being grounded, in some exemplary embodiments, the anodes of the light-emitting diodes may be connected in common and their cathodes may be connected to different transistors.

[0493] Although an active circuit for active matrix driving is shown above, the inventive concept is not limited thereto, and the pixels according to the exemplary embodiments can be driven in a passive matrix manner. In this way, the circuit board 3510 may include data lines and scan lines arranged thereon, and each sub-pixel may be connected to the data line and the scan line. In an exemplary embodiment, the anodes of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may be connected to different data lines, and their cathodes may be commonly connected to the scan line. In other exemplary embodiments, the anodes of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may be connected to different scan lines, and their cathodes may be commonly connected to the data line.

[0494] Furthermore, each of the LED stacks 3230, 3330, and 3430 can be driven through pulse width modulation or by varying the magnitude of the current, thereby controlling the brightness of each subpixel. Furthermore, the brightness can be adjusted by adjusting the areas of the first, second, and third LED stacks 3230, 3330, and 3430, as well as the areas of the regions through which the R, G, and B light rays of the LED stacks 3230, 3330, and 3430 are emitted. For example, an LED stack emitting light with low visibility (e.g., the first LED stack 3230) has a larger area than the second or third LED stacks 3330 and, therefore, can emit light with higher intensity at the same current density. Furthermore, 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 intensity at the same current density compared to the third LED stack 3430. In this manner, light output may be adjusted based on visibility of light emitted from the first, second, and third LED stacks 3230 , 3330 , and 3430 by adjusting the areas of the first, second, and third LED stacks 3230 , 3330 , and 3430 .

[0495] Figure 59A and Figure 59B are top and bottom views of one pixel of a display device according to an exemplary embodiment, Figure 60A 、 Figure 60B 、 Figure 60C and Figure 60D Along the Figure 59A Schematic cross-sectional views taken along lines AA, BB, CC and DD.

[0496] In the display device, pixels are arranged on a circuit board 3510 (see Figure 56), and each pixel includes a substrate 3210 and sub-pixels R, G, and B. The substrate 3210 may be continuous for a plurality of pixels. Hereinafter, a configuration of a pixel according to an exemplary embodiment will be described.

[0497] Reference Figure 59A 、 Figure 59B 、 Figure 60A 、 Figure 60B 、 Figure 60C and Figure 60D The pixel includes a substrate 3210, a distributed Bragg reflector 3220, an insulating layer 3250, through-hole vias 3270a, 3270b, 3270c, a first LED stack 3230, a second LED stack 3330, a third LED stack 3430, a first-1 ohmic electrode 3290a, a first-2 ohmic electrode 3290b, 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, 3730, a lower insulating layer 3750, and electrode pads 3770a, 3770b, 3770c, 3770d.

[0498] Each of the sub-pixels R, G, and B includes an LED stack 3230, 3330, and 3430 and an ohmic electrode. Furthermore, the anodes of the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B can be electrically connected to electrode pads 3770a, 3770b, and 3770c, respectively, while their cathodes can be electrically connected to electrode pad 3770d, thereby allowing the first sub-pixel R, the second sub-pixel G, and the third sub-pixel B to be driven independently.

[0499] The substrate 3210 supports the LED stacks 3230, 3330, and 3430. The substrate 3210 may be a growth substrate (eg, a GaAs substrate) on which an AlGaInP-based semiconductor layer may be grown. Specifically, the substrate 3210 may be a semiconductor substrate exhibiting n-type conductivity.

[0500] The first LED stack 3230 includes a first conductive type semiconductor layer 3230a and a second conductive type semiconductor layer 3230b. The second LED stack 3330 includes a first conductive type semiconductor layer 3330a and a second conductive type semiconductor layer 3330b. The third LED stack 3430 includes a first conductive type semiconductor layer 3430a and a second conductive type semiconductor layer 3430b. An active layer may be interposed between the first conductive type semiconductor layer 3230a, 3330a, or 3430a and the second conductive type semiconductor layer 3230b, 3330b, or 3430b.

[0501] According to an exemplary embodiment, each of the first conductive type semiconductor layers 3230a, 3330a, and 3430a may be an n-type semiconductor layer, and each of the second conductive type semiconductor layers 3230b, 3330b, and 3430b may be a p-type semiconductor layer. A rough surface may be formed on the upper surface of each of the first conductive type semiconductor layers 3230a, 3330a, and 3430a by surface texturing. However, the inventive concept is not limited thereto, and the first and second conductive types may be reversely changed.

[0502] The first LED stack 3230 is disposed near the substrate 3210, 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 region on the first LED stack 3230 such that the first LED stack 3230 partially overlaps the second LED stack 3330. The third LED stack 3430 is disposed in a region on the second LED stack 3330 such that the second LED stack 3330 partially overlaps the third LED stack 3430. Therefore, light generated from the first LED stack 3230 can be emitted to the outside without passing through the second LED stack 3330 and the third LED stack 3430. In addition, light generated from the second LED stack 3330 can be emitted to the outside without passing through the third LED stack 3430.

[0503] Materials and References for the First LED Stack 3230 , the Second LED Stack 3330 , and the Third LED Stack 3430 Figure 57 The materials described for the first LED stack 3230 , the second LED stack 3330 , and the third LED stack 3430 are substantially the same, and thus, detailed descriptions thereof will be omitted to avoid redundancy.

[0504] The distributed Bragg reflector 3220 is disposed between the substrate 3210 and the first LED stack 3230. The distributed Bragg reflector 3220 may include a semiconductor layer grown on the substrate 3210. For example, the distributed Bragg reflector 3220 may be formed by alternately stacking AlAs layers and AlGaAs layers. The distributed Bragg reflector 3220 may include a semiconductor layer that electrically connects the substrate 3210 to the first conductive type semiconductor layer 3230a of the first LED stack 3230.

[0505] Vias 3270a, 3270b, 3270c are formed through the substrate 3210. The vias 3270a, 3270b, 3270c may be formed through the first LED stack 3230. The vias 3270a, 3270b, 3270c may be formed of a conductive paste or by electroplating.

[0506] The insulating layer 3250 is disposed between the vias 3270 a , 3270 b , and 3270 c and sidewalls of the through-holes formed through the substrate 3210 and the first LED stack 3230 to prevent a short circuit between the first LED stack 3230 and the substrate 3210 .

[0507] The first-1 ohmic electrode 3290a makes ohmic contact with the first conductive type semiconductor layer 3230a of the first LED stack 3230. The first-1 ohmic electrode 3290a may be formed of, for example, an Au-Te alloy or an Au-Ge alloy.

[0508] In order to form the first-1 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-1 ohmic electrode 3290a may be provided to be separated from the region where the second LED stack 3330 is provided. Figure 59A As shown in , the first-1 ohmic electrode 3290 a may include a pad region and an extension, and a connector 3710 may be connected to the pad region of the first-1 ohmic electrode 3290 a .

[0509] The first -2 ohmic electrode 3290b forms an ohmic contact with the second conductive type semiconductor layer 3230b of the first LED stack 3230. Figure 59A As shown in FIG, the first-2 ohm electrode 3290b can be formed to partially surround the first-1 ohm electrode 3290a, thereby facilitating current diffusion. The first-2 ohm electrode 3290b may not include an extension portion. The first-2 ohm electrode 3290b may be formed of, for example, an Au-Zn alloy or an Au-Be alloy. Furthermore, the first-2 ohm electrode 3290b may have a single-layer structure or a multi-layer structure.

[0510] The first -2 ohmic electrode 3290 b may be connected to the via 3270 a so that the via 3270 a may be electrically connected to the second conductive type semiconductor layer 3230 b .

[0511] The second-1 ohmic electrode 3390 forms an ohmic contact with the first conductive type semiconductor layer 3330a of the second LED stack 3330. The second-1 ohmic electrode 3390 may also include a pad region and an extension portion. Figure 59AAs shown in FIG, the connector 3710 may electrically connect the second-1 ohmic electrode 3390 to the first-1 ohmic electrode 3290a. The second-1 ohmic electrode 3390 may be disposed apart from a region where the third LED stack 3430 is disposed.

[0512] The second-2 ohmic electrode 3350 forms an ohmic contact with the second conductive semiconductor layer 3330b of the second LED stack 3330. The second-2 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-2 ohmic electrode 3350 is described as including a metal layer in this exemplary embodiment, the inventive concept is not limited thereto. For example, the second-2 ohmic electrode 3350 may be formed of a transparent conductive oxide (such as a conductive oxide semiconductor layer).

[0513] The third-1 ohmic electrode 3490 forms an ohmic contact with the first conductive semiconductor layer 3430a of the third LED stack 3430. Figure 59A As shown in , the third-1 ohmic electrode 3490 may also include a pad region and an extension portion, and a connector 3710 may connect the third-1 ohmic electrode 3490 to the first-1 ohmic electrode 3290 a .

[0514] The third-2 ohmic electrode 3450 can form an ohmic contact with the second conductive semiconductor layer 3430b of the third LED stack 3430. The third-2 ohmic electrode 3450 can 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 can serve as a connection pad for providing the reflective layer 3450a and is connected to the connector 3730. Although the third-2 ohmic electrode 3450 is described as including a metal layer, the inventive concept is not limited thereto. Alternatively, the third-2 ohmic electrode 3450 can be formed of a transparent conductive oxide (such as a conductive oxide semiconductor layer).

[0515] The first-2 ohm electrode 3290b, the second-2 ohm electrode 3350 and the third-2 ohm electrode 3450 can form an ohmic contact with the p-type semiconductor layer of the corresponding LED stack to facilitate current diffusion, and the first-1 ohm electrode 3290a, the second-1 ohm electrode 3390 and the third-1 ohm electrode 3490 can form an ohmic contact with the n-type semiconductor layer of the corresponding LED stack to facilitate current diffusion.

[0516] The first bonding layer 3530 bonds the second LED stack 3330 to the first LED stack 3230. As shown in the figure, the second -2 ohm electrode 3350 may be adjacent to the first bonding layer 3530. The first bonding layer 3530 may be a light-transmitting layer or an opaque layer. The first bonding layer 3530 may be formed of an organic material or an inorganic material. Examples of organic materials may include SU8, poly(methyl methacrylate) (PMMA), polyimide, parylene, benzocyclobutene (BCB), etc., and examples of inorganic materials may include Al2O3, SiO2, SiN x The organic material layer can be bonded under high vacuum, and the inorganic material layer can be bonded under high vacuum after the surface of the first bonding layer is flattened by, for example, chemical mechanical polishing and then the surface energy is adjusted by plasma treatment. The first bonding layer 3530 can be formed of spin-on glass, or it can be a metal bonding layer formed of AuSn or the like. For the metal bonding layer, an insulating layer can be provided on the first LED stack 3230 to ensure electrical insulation between the first LED stack 3230 and the metal bonding layer. In addition, a reflective layer can be provided between the first bonding layer 3530 and the first LED stack 3230 to prevent light generated from the first LED stack 3230 from entering the second LED stack 3330.

[0517] The second bonding layer 3550 bonds the second LED stack 3330 to the third LED stack 3430. The second bonding layer 3550 may be interposed between the second LED stack 3330 and the third -2 ohmic electrode 3450 to bond the second LED stack 3330 to the third -2 ohmic electrode 3450. The second bonding layer 3550 may be formed of a bonding material substantially the same as that of the first bonding layer 3530. Furthermore, an insulating layer and / or a reflective layer may be further disposed between the second LED stack 3330 and the second bonding layer 3550.

[0518] When the first bonding layer 3530 and the second bonding layer 3550 are formed of a light-transmitting material, and the second 2-ohm electrode 3350 and the third 2-ohm electrode 3450 are formed of a transparent oxide material, some portion of the light generated from the first LED stack 3230 may be emitted through the second LED stack 3330 after passing through the first bonding layer 3530 and the second 2-ohm electrode 3350, and may also be emitted through the third LED stack 3430 after passing through the second bonding layer 3550 and the third 2-ohm electrode 3450. In addition, some portion of the light generated from the second LED stack 3330 may be emitted through the third LED stack 3430 after passing through the second bonding layer 3550 and the third 2-ohm electrode 3450.

[0519] In this case, the light generated from the first LED stack 3230 should be prevented from being absorbed by the second LED stack 3330 when passing through the second LED stack 3330. As such, the light generated from the first LED stack 3230 may have a smaller band gap than that of the second LED stack 3330, and thus the wavelength of the light generated from the first LED stack 3230 may be longer than that of the light generated from the second LED stack 3330.

[0520] Furthermore, to prevent light generated from the second LED stack 3330 from being absorbed by the third LED stack 3430 when passing through the third LED stack 3430 , the wavelength of light generated from the second LED stack 3330 may be longer than that of light generated from the third LED stack 3430 .

[0521] When the first bonding layer 3530 and the second bonding layer 3550 are formed of an opaque material, reflective layers are 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, to reflect light that has been generated from the first LED stack 3230 and entered the first bonding layer 3530, and light that has been generated from the second LED stack 3330 and entered the second bonding layer 3550. The reflected light may be emitted through the first LED stack 3230 and the second LED stack 3330.

[0522] The upper insulating layer 3610 may cover the first LED stack 3230 , the second LED stack 3330 , and the third LED stack 3430 . Specifically, the upper insulating layer 3610 may cover side surfaces of the second LED stack 3330 and the third LED stack 3430 , and may also cover side surfaces of the first LED stack 3230 .

[0523] The upper insulating layer 3610 has openings exposing the first via 3270a, the second via 3270b, and the third via 3270c, as well as openings exposing the first conductive semiconductor layer 3330a of the second LED stack 3330, the first conductive semiconductor layer 3430a of the third LED stack 3430, the second -2 ohm electrode 3350, and the third -2 ohm electrode 3450.

[0524] The upper insulating layer 3610 may be formed of any insulating material, such as silicon oxide or silicon nitride, but is not limited thereto.

[0525] The connector 3710 electrically connects the first-1 ohmic electrode 3290a, the second-1 ohmic electrode 3390, and the third-1 ohmic electrode 3490. The connector 3710 is formed on the upper insulating layer 3610 and is insulated from the second conductive type semiconductor layer 3430b of the third LED stack 3430, the second conductive type semiconductor layer 3330b of the second LED stack 3330, and the second conductive type semiconductor layer 3230b of the first LED stack 3230.

[0526] The connector 3710 may be formed of a material substantially the same as that of the second-1 ohmic electrode 3390 and the third-1 ohmic electrode 3490, and thus, may be formed together with the second-1 ohmic electrode 3390 and the third-1 ohmic electrode 3490. Alternatively, the connector 3710 may be formed of a conductive material different from that of the second-1 ohmic electrode 3390 or the third-1 ohmic electrode 3490, and thus, may be formed separately using a process different from that of the second-1 ohmic electrode 3390 and / or the third-1 ohmic electrode 3490.

[0527] The connector 3720 can electrically connect the second 2-ohm electrode 3350 (e.g., barrier layer 3350b) to the second via 3270b. The connector 3730 can electrically connect the third 2-ohm electrode (e.g., barrier layer 3450b) to the third via 3270c. The connector 3720 can be electrically insulated from the first LED stack 3230 by the upper insulating layer 3610. The connector 3730 can also be electrically insulated from the second LED stack 3330 and the first LED stack 3230 by the upper insulating layer 3610.

[0528] The connectors 3720 and 3730 may be formed together through the same process. The connectors 3720 and 3730 may also be formed together with the connector 3710. Furthermore, the connectors 3720 and 3730 may be formed of a material substantially the same as that of the second-1 ohmic electrode 3390 and the third-1 ohmic electrode 3490, and may be formed together with the second-1 ohmic electrode 3390 and the third-1 ohmic electrode 3490. Alternatively, the connectors 3720 and 3730 may be formed of a conductive material different from that of the second-1 ohmic electrode 3390 or the third-1 ohmic electrode 3490, and thus may be formed separately through a process different from that of the second-1 ohmic electrode 3390 and / or the third-1 ohmic electrode 3490.

[0529] The lower insulating layer 3750 covers the lower surface of the substrate 3210. The lower insulating layer 3750 may include openings at the lower side of the substrate 3210 that expose the first, second, and third vias 3270a, 3270b, and 3270c, and may also include openings that expose the lower surface of the substrate 3210.

[0530] Electrode pads 3770a, 3770b, 3770c, and 3770d are provided on the lower surface of the substrate 3210. The electrode pads 3770a, 3770b, and 3770c are connected to the vias 3270a, 3270b, and 3270c through the openings of the lower insulating layer 3750, and the electrode pad 3770d is connected to the substrate 3210.

[0531] Electrode pads 3770a, 3770b, and 3770c are provided for each pixel to be electrically connected to the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 of each pixel, respectively. Although an electrode pad 3770d may also be provided for each pixel, the substrate 3210 is continuously provided for a plurality of pixels, which may eliminate the need for providing an electrode pad 3770d for each pixel.

[0532] The electrode pads 3770a, 3770b, 3770c, 3770d are bonded to the circuit board 3510, thereby providing a display device.

[0533] Next, a method of manufacturing a display apparatus according to an exemplary embodiment will be described.

[0534] Figures 61A to 68B Schematic plan views and cross-sectional views illustrating a method of manufacturing a display device according to an exemplary embodiment. Each cross-sectional view is taken along line EE or FF shown in each corresponding plan view.

[0535] Reference Figure 61A and Figure 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. A distributed Bragg reflector 3220 may be formed before growing the first LED stack 3230. The distributed Bragg reflector 3220 may have a stacked structure formed by repeatedly stacking, for example, AlAs layers / AlGaAs layers.

[0536] Then, grooves are formed on the first LED stack 3230 and the substrate 3210 by photolithography and etching. The grooves may be formed through the substrate 3210 or may be formed in the substrate 3210 to a predetermined depth, such as Figure 61B As shown in .

[0537] Then, an insulating layer 3250 is formed to cover the sidewalls of the groove, and vias 3270a, 3270b, and 3270c are formed to fill the groove. The vias 3270a, 3270b, and 3270c can be formed by, for example, forming an insulating layer to cover the sidewalls of the groove, filling the groove with a conductive material layer or conductive paste by electroplating, and removing the insulating layer and the conductive material layer from the upper surface of the first LED stack 3230 by chemical mechanical polishing.

[0538] Reference Figure 62A and Figure 62B , the second LED stack 3330 and the second -2 ohmic electrode 3350 may be bonded to the first LED stack 3230 via the first bonding layer 3530 .

[0539] A second LED stack 3330 is grown on a second substrate, and a second-2 ohmic electrode 3350 is formed on the second LED stack 3330. The second LED stack 3330 is formed of an AlGaInP-based semiconductor layer or an 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 (e.g., a GaAs substrate), or a substrate on which an AlGaInN-based semiconductor layer can be grown (e.g., a sapphire substrate). The composition ratio of Al, Ga, and In for the second LED stack 3330 may be determined so that the second LED stack 3330 can emit green light. The second-2 ohmic electrode 3350 forms an ohmic contact with the second conductivity-type semiconductor layer 3330b (e.g., a p-type semiconductor layer). The second-2 ohmic electrode 3350 may include a reflective layer 3350a and a barrier layer 3350b that reflect light generated by the second LED stack 3330.

[0540] The second -2 ohm electrode 3350 is disposed facing the first LED stack 3230 and is bonded to the first LED stack 3230 via the first bonding layer 3530. Thereafter, the second substrate is removed from the second LED stack 3330 by chemical etching or laser lift-off to expose the first conductive semiconductor layer 3330a. A rough surface may be formed on the exposed first conductive semiconductor layer 3330a by surface texturing.

[0541] According to an exemplary embodiment, an insulating layer and a reflective layer may be further formed on the first LED stack 3230 before forming the first bonding layer 3530 .

[0542] Reference Figure 63A and Figure 63B, the third LED stack 3430 and the third -2 ohmic electrode 3450 may be bonded to the second LED stack 3330 via a second bonding layer 3550 .

[0543] A third LED stack 3430 is grown on a third substrate, and a third-2 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 an AlGaInN-based semiconductor layer can be grown and is different from the first substrate 3210. The composition ratio of AlGaInN used in the third LED stack 3430 can be determined so that the third LED stack 3430 can emit blue light. The third-2 ohmic electrode 3450 forms an ohmic contact with the second-conductivity-type semiconductor layer 3430b (e.g., a p-type semiconductor layer). The third-2 ohmic electrode 3450 may include a reflective layer 3450a and a barrier layer 3450b that reflect light generated by the third LED stack 3430.

[0544] The third 2-ohm electrode 3450 is disposed facing the second LED stack 3330 and is bonded to the second LED stack 3330 via the second bonding layer 3550. Thereafter, the third substrate is removed from the third LED stack 3430 by chemical etching or laser lift-off to expose the first conductive semiconductor layer 3430a. A rough surface may be formed on the exposed first conductive semiconductor layer 3430a by surface texturing.

[0545] According to an exemplary embodiment, an insulating layer and a reflective layer may be further formed on the second LED stack 3330 before forming the second bonding layer 3550 .

[0546] Reference Figure 64A and Figure 64B In each pixel region, the third LED stack 3430 is patterned to remove the third LED stack 3430 except in the third sub-pixel B. In the region of the third sub-pixel B, an indentation is formed on the third LED stack 3430 to expose the blocking layer 3450 b through the indentation.

[0547] Then, in the region except the third sub-pixel B, the third-2 ohmic electrode 3450 and the second bonding layer 3550 are removed to expose the second LED stack 3330. In this manner, the third-2 ohmic electrode 3450 is restrictively positioned near the region of the third sub-pixel B.

[0548] In each pixel region, the second LED stack 3330 is patterned to remove the second LED stack 3330 in a region other than the second sub-pixel G. In the region of the second sub-pixel G, the second LED stack 3330 partially overlaps the third LED stack 3430 .

[0549] The second-2 ohmic electrode 3350 is exposed by patterning the second LED stack 3330. The second LED stack 3330 may include a notch, and the second-2 ohmic electrode 3350 (eg, the barrier layer 3350b) may be exposed through the notch.

[0550] Thereafter, the second-2 ohmic electrode 3350 and the first bonding layer 3530 are removed to expose the first LED stack 3230. In this manner, the second-2 ohmic electrode 3350 is disposed near the region of the second sub-pixel G. On the other hand, the first via 3270a, the second via 3270b, and the third via 3270c are also exposed along with the first LED stack 3230.

[0551] 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. Figure 64A As shown in FIG, the first conductive type semiconductor layer 3230a may be exposed in an elongated shape, but is not limited thereto.

[0552] Furthermore, the pixel regions are separated from each other by patterning the first LED stack 3230. This defines the region of the first sub-pixel R. The distributed Bragg reflector 3220 may also be divided. Alternatively, the distributed Bragg reflector 3220 may be provided continuously for multiple pixels without being divided. Furthermore, the first conductive semiconductor layer 3230a may also be provided continuously for multiple pixels.

[0553] Reference Figure 65A and Figure 65B , a first-1 ohmic electrode 3290a and a first-2 ohmic electrode 3290b are formed on the first LED stack 3230. The first-1 ohmic electrode 3290a can be formed from, for example, an Au-Te alloy or an Au-Ge alloy on the exposed first conductive type semiconductor layer 3230a. The first-2 ohmic electrode 3290b can be formed from, for example, an Au-Be alloy or an Au-Zn alloy on the second conductive type semiconductor layer 3230b. The first-2 ohmic electrode 3290b can be formed before the first-1 ohmic electrode 3290a, or vice versa. The first-2 ohmic electrode 3290b can be connected to the first via 3270a. Alternatively, the first-1 ohmic electrode 3290a can include a pad region and an extension portion that can extend from the pad region toward the first via 3270a.

[0554] For current spreading, the first -2 ohm electrode 3290b may be disposed to at least partially surround the first -1 ohm electrode 3290a. Figure 65A Each of the first-1 ohmic electrode 3290a and the first-2 ohmic electrode 3290b is shown as having an elongated shape, but the inventive concept is not limited thereto. Alternatively, each of the first-1 ohmic electrode 3290a and the first-2 ohmic electrode 3290b may have, for example, a circular shape.

[0555] Reference Figure 66A and Figure 66B The upper insulating layer 3610 is formed to cover the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430. The upper insulating layer 3610 may cover the first-1 ohmic electrode 3290a and the first-2 ohmic electrode 3290b. The upper insulating layer 3610 may also cover the side surfaces of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430, as well as the side surfaces of the distributed Bragg reflector 3220.

[0556] The upper insulating layer 3610 may have an opening 3610a exposing the first -1 ohm electrode 3290a, an opening 3610b exposing the blocking layer 3350b, an opening 3610c exposing the blocking layer 3450b, an opening 3610d exposing the second path 3270b, an opening 3610e exposing the third path 3270c, an opening 3610f exposing the first conductive semiconductor layer 3330a of the second LED stack 3330, and an opening 3610g exposing the first conductive semiconductor layer 3430a of the third LED stack 3430.

[0557] Reference Figure 67A and Figure 67B , forming a second-1 ohmic electrode 3390, a third-1 ohmic electrode 3490, and connectors 3710, 3720, and 3730. The second-1 ohmic electrode 3390 is formed in the opening 3610f to form an ohmic contact with the first conductive type semiconductor layer 3330a, and the third-1 ohmic electrode 3490 is formed in the opening 3610g to form an ohmic contact with the first conductive type semiconductor layer 3430a.

[0558] The connector 3710 electrically connects the second-1 ohmic electrode 3390 and the third-1 ohmic electrode 3490 to the first-1 ohmic electrode 3290a. The connector 3710 may be connected to, for example, the first-1 ohmic electrode 3290a exposed in the opening 3610a. The connector 3710 is formed on the upper insulating layer 3610 to insulate from the second conductive type semiconductor layers 3230b, 3330b, and 3430b.

[0559] The second-2 ohm electrode 3350 is electrically connected to the second via 3270b by a connector 3720, and the third-2 ohm electrode 3450 is electrically connected to the third via 3270c by a connector 3730. The connectors 3720 and 3730 are provided on the upper insulating layer 3610 to prevent short circuits in the first, second, and third LED stacks 3230, 3330, and 3430.

[0560] The second-1 ohmic electrode 3390, the third-1 ohmic electrode 3490, and the connectors 3710, 3720, and 3730 can be formed of substantially the same material through the same process. However, the inventive concept is not limited thereto. Alternatively, the second-1 ohmic electrode 3390, the third-1 ohmic electrode 3490, and the connectors 3710, 3720, and 3730 can be formed of different materials through different processes.

[0561] Afterwards, refer to Figure 68A and Figure 68B , a lower insulating layer 3750 is formed on the lower surface of the substrate 3210. The lower insulating layer 3750 has openings exposing the first via 3270a, the second via 3270b, and the third via 3270c, and may further have (one or more) openings exposing the lower surface of the substrate 3210.

[0562] 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 via 3270a, the second via 3270b, and the third via 3270c, respectively, and the electrode pad 3770d is connected to the substrate 3210.

[0563] Therefore, the electrode pad 3770a is electrically connected to the second conductive semiconductor layer 3230b of the first LED stack 3230 through the first via 3270a, the electrode pad 3770b is electrically connected to the second conductive semiconductor layer 3330b of the second LED stack 3330 through the second via 3270b, and the electrode pad 3770c is electrically connected to the second conductive semiconductor layer 3430b of the third LED stack 3430 through the third via 3270c. The first conductive semiconductor layer 3230a of the first LED stack 3230, the first conductive semiconductor layer 3330a of the second LED stack 3330, and the first conductive semiconductor layer 3430a of the third LED stack 3430 are commonly electrically connected to the electrode pad 3770d.

[0564] In this way, the electrode pads 3770a, 3770b, 3770c, 3770d of the substrate 3210 can be bonded to Figure 56The display device according to the exemplary embodiment is formed by using the circuit board 3510 shown in FIG. As described above, the circuit board 3510 may include an active circuit or a passive circuit, so that the display device can be driven in an active matrix manner or a passive matrix manner.

[0565] Figure 69 is a cross-sectional view of a light emitting diode pixel for a display device according to another exemplary embodiment.

[0566] Reference Figure 69 , 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, the light emitting diode pixel 3001 of the display device according to the exemplary embodiment is generally similar to Figure 57 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.

[0567] The first LED stack 3230 may include an active layer having a narrower band gap than the second LED stack 3330 and the third LED stack 3430 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 band gap than the third LED stack 3430 to emit light having a longer wavelength than the third LED stack 3430.

[0568] Figure 70 is an enlarged top view of one pixel of a display device according to an exemplary embodiment, Figure 71A and Figure 71B Along the Figure 70 A cross-sectional view taken along line GG and line HH.

[0569] Reference Figure 70 、 Figure 71A and Figure 71B , 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, the pixel according to the exemplary embodiment is generally similar to Figure 59A 、 Figure 59B 、 Figure 60A 、 Figure 60B 、 Figure 60C and Figure 60DThe first path 3270 a , the second path 3270 b , and the third path 3270 c may be provided outside the second LED stack 3330 and the third LED stack 3430 .

[0570] In addition, a portion of the first-1 ohmic electrode 3290a and a portion of the second-1 ohmic electrode 3390 may be disposed under the third LED stack 3430. As such, the first-1 ohmic electrode 3290a may be formed before the second LED stack 3330 is coupled to the first LED stack 3230, and the second-1 ohmic electrode 3390 may also be formed before the third LED stack 3430 is coupled to the second LED stack 3330.

[0571] In addition, light generated from the first LED stack 3230 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. Therefore, the first bonding layer 3530 and the second bonding layer 3550 are formed of a light-transmitting material, and the second-2 ohm electrode 3350 and the third-2 ohm electrode 3450 are composed of a transparent conductive layer.

[0572] On the other hand, Figure 71A and Figure 71B As shown in FIG, a notch may be formed on the third LED stack 3430 to expose the third-2 ohmic electrode 3450, and a notch may be continuously formed on the third LED stack 3430 and the second LED stack 3330 to expose the second-2 ohmic electrode 3350. The second-2 ohmic electrode 3350 and the third-2 ohmic electrode 3450 are electrically connected to the second via 3270b and the third via 3270c through connectors 3720 and 3730, respectively.

[0573] Furthermore, a notch may be formed on the third LED stack 3430 to expose the second-1 ohmic electrode 3390 formed on the first conductive type semiconductor layer 3330a of the second LED stack 3330, and a notch may be continuously formed on the third LED stack 3430 and the second LED stack 3330 to expose the first-1 ohmic electrode 3290a formed on the first conductive type semiconductor layer 3230a of the first LED stack 3230. A connector 3710 may connect the first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390 to the third-1 ohmic electrode 3490. The third-1 ohmic electrode 3490 may be formed together with the connector 3710 and may be connected to pad regions of the first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390.

[0574] The first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390 are partially disposed under the third LED stack 3430, but the inventive concept is not limited thereto. For example, the portions of the first-1 ohmic electrode 3290a and the second-1 ohmic electrode 3390 disposed under the third LED stack 3430 may be omitted. Furthermore, the second-1 ohmic electrode 3390 may be omitted, and the connector 3710 may form an ohmic contact with the first conductive type semiconductor layer 3330a.

[0575] According to example embodiments, a plurality of pixels may be formed at a wafer level through wafer bonding, and thus, a process of separately mounting light emitting diodes may be eliminated or substantially reduced.

[0576] Furthermore, since the vias 3270a, 3270b, and 3270c are formed in the substrate 3210 and serve as current paths, there is no need to remove the substrate 3210. Therefore, the growth substrate used for growing the first LED stack 3230 can be used as the substrate 3210 without being removed from the first LED stack 3230.

[0577] Figure 72 is a schematic cross-sectional view of a light emitting diode (LED) stack for a display according to an exemplary embodiment.

[0578] Reference Figure 72 , a light emitting diode stack 4000 for a display may include a supporting 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 4053 (lower bonding layer), a second bonding layer 4055 (middle bonding layer) and a third bonding layer 4057 (upper bonding layer).

[0579] The support substrate 4051 supports the semiconductor stacks 4023, 4033, and 4043. The support substrate 4051 may have a circuit on its surface or inside, but is not limited thereto. The support substrate 4051 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

[0580] Each of the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 includes first conductive semiconductor layers 4023a, 4033a, and 4043a, second conductive semiconductor layers 4023b, 4033b, and 4043b, and an active layer disposed between the first and second conductive semiconductor layers. The active layer may have a multi-quantum well structure.

[0581] 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 base well layer, and the second and third LED stacks 4033 and 4043 may include a GaInN base well layer. However, the inventive concept is not limited thereto. When the LED stack includes a microLED, 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 different ones of red, green, and blue light, without adversely affecting operation or requiring color filters due to their small form factors.

[0582] Opposite surfaces of each LED stack 4023, 4033, or 4043 are respectively an n-type semiconductor layer and a p-type semiconductor layer. The illustrated exemplary embodiment describes a case where the first conductivity-type semiconductor layer 4023a, 4033a, and 4043a of each of the first, second, and third LED stacks 4023, 4033, and 4043 is n-type, and the second conductivity-type semiconductor layer 4023b, 4033b, and 4043b thereof is p-type. A roughened surface may be formed on the upper surfaces of the first, second, and third LED stacks 4023, 4033, and 4043. However, the inventive concept is not limited thereto, and the semiconductor types of the upper and lower surfaces of each LED stack may be reversed.

[0583] The first LED stack 4023 is disposed adjacent to the supporting base 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. Since the first LED stack 4023 emits light having a longer wavelength than the second and third LED stacks 4033 and 4043, light generated in the first LED stack 4023 can be transmitted through the second and third LED stacks 4033 and 4043 and emitted to the outside. Furthermore, since the second LED stack 4033 emits light having a longer wavelength than the third LED stack 4043, light generated in the second LED stack 4033 can be transmitted through the third LED stack 4043 and emitted to the outside.

[0584] The reflective electrode 4025 makes 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.

[0585] The ohmic contact layer 4025a partially contacts the second conductivity-type semiconductor layer (i.e., the p-type semiconductor layer). To prevent light from being absorbed by the ohmic contact layer 4025a, the area of ​​the ohmic contact layer 4025a in contact with the p-type semiconductor layer may not exceed approximately 50% of the total area of ​​the p-type semiconductor layer. The reflective layer 4025b covers the ohmic contact layer 4025a and also covers the first insulating layer 4027. As shown in the figure, the reflective layer 4025b may substantially cover the entire ohmic contact layer 4025a or a portion of the ohmic contact layer 4025a.

[0586] The reflective layer 4025b covers the first insulating layer 4027, so that an omnidirectional reflector can be formed by 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 approximately 50% or more of the area of ​​the first LED stack 4023, preferably covering most of the area of ​​the first LED stack 4023, thereby improving light efficiency.

[0587] The ohmic contact layer 4025a and the reflective layer 4025b can be formed of a metal layer containing gold (Au). The ohmic contact layer 4025a can be formed of, for example, an Au-Zn alloy or an Au-Be alloy. The reflective layer 4025b can be formed of a metal layer (such as aluminum (Al), silver (Ag), or gold (Au)) having a high reflectivity relative to the light (e.g., red light) generated in the first LED stack 4023. Specifically, Au can have a relatively low reflectivity relative to the light (e.g., green light or blue light) generated in the second LED stack 4033 and the third LED stack 4043, thereby reducing light interference by absorbing the light generated in the second LED stack 4033 and the third LED stack 4043 and propagating toward the supporting substrate 4051.

[0588] 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 within the opening of the first insulating layer 4027.

[0589] The ohmic electrode 4026 makes ohmic contact with the first conductive type semiconductor layer 4023a of the first LED stack 4023. The ohmic electrode 4026 may be provided on the first conductive type semiconductor layer 4023a exposed by partially removing the second conductive type semiconductor layer 4023b. Figure 72 One ohmic electrode 4026 is shown, but a plurality of ohmic electrodes 4026 are aligned on a plurality of regions on the support substrate 4051. The ohmic electrode 4026 may be formed of, for example, an Au-Te alloy or an Au-Ge alloy.

[0590] The second insulating layer 4028 is provided between the support substrate 4051 and the reflective electrode 4025 to cover the reflective electrode 4025. The second insulating layer 4028 has an opening exposing the ohmic electrode 4026. The second insulating layer 4028 may be formed of SiO2 or SOG.

[0591] The interconnection line 4029 is provided between the second insulating layer 4028 and the support substrate 4051 and is connected to the ohmic electrode 4026 through the opening of the second insulating layer 4028. The interconnection line 4029 can connect the plurality of ohmic electrodes 4026 to each other on the support substrate 4051.

[0592] The second p transparent electrode 4035 makes ohmic contact with the second conductive semiconductor layer 4033b (ie, p-type semiconductor layer) of the second LED stack 4033. The second p transparent electrode 4035 may be formed of a metal layer or a conductive oxide layer transparent to red and green light.

[0593] The third p transparent electrode 4045 makes ohmic contact with the second conductive semiconductor layer 4043b (ie, p-type semiconductor layer) of the third LED stack 4043. The third p transparent electrode 4045 may be formed of a metal layer or a conductive oxide layer transparent to red, green, and blue light.

[0594] The reflective electrode 4025 , the second p transparent electrode 4035 , and the third p transparent electrode 4045 may make ohmic contact with the p-type semiconductor layer of each LED stack to facilitate current spreading.

[0595] A first color filter 4037 may be provided between the first LED stack 4023 and the second LED stack 4033. Furthermore, a second color filter 4047 may be provided 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 LED stack 4023 and the second LED stack 4033 and reflects light generated in the third LED stack 4043. Therefore, light generated in the first LED stack 4023 may be emitted to the outside through the second LED stack 4033 and the third LED stack 4043, and light generated in the second LED stack 4033 may be emitted to the outside through the third LED stack 4043. Furthermore, it is possible to prevent light generated in the second LED stack 4033 from being incident on the first LED stack 4023 and lost, or it is possible to prevent light generated in the third LED stack 4043 from being incident on the second LED stack 4033 and lost.

[0596] According to some exemplary embodiments, the first color filter 4037 may also reflect light generated in the third LED stack 4043. According to some exemplary embodiments, when the LED stack includes micro-LEDs, the color filter may be omitted due to the small form factor of the micro-LEDs.

[0597] The first color filter 4037 and the second color filter 4047 can be, for example, a low-pass filter that only allows the low-frequency region (i.e., the long-wavelength region) to pass, a band-pass filter that only allows a predetermined wavelength band to pass, or a band-stop filter that only blocks a predetermined wavelength band. Specifically, the first color filter 4037 and the second color filter 4047 can be formed by alternately stacking insulating layers having different refractive indices, and can be formed by alternately stacking, for example, TiO2 and SiO2, Ta2O5 and SiO2, Nb2O5 and SiO2, HfO2 and SiO2, or ZrO2 and SiO2. In addition, the first color filter 4037 and / or the second color filter 4047 can include a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers having different refractive indices. In addition, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of TiO2 and SiO2.

[0598] The first bonding layer 4053 bonds the first LED stack 4023 to the supporting substrate 4051. As shown, the interconnection line 4029 may be in contact with the first bonding layer 4053. In addition, the interconnection line 4029 is disposed below some areas of the second insulating layer 4028, and areas of the second insulating layer 4028 that do not have the interconnection line 4029 may be in contact with the first bonding layer 4053. The first bonding layer 4053 may be light-transmissive or light-opaque. Specifically, 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.

[0599] The first bonding layer 4053 may be in direct contact with the supporting substrate 4051, but as shown in the figure, a hydrophilic material layer 4052 may be provided at the interface between the supporting substrate 4051 and the first bonding layer 4053. The hydrophilic material layer 4052 may change the surface of the supporting substrate 4051 to be hydrophilic to improve the adhesion of the first bonding layer 4053. As used herein, the bonding layer and the hydrophilic material layer may be collectively referred to as a buffer layer.

[0600] The first bonding layer 4053 has strong adhesion to the hydrophilic material layer, but weak adhesion to the hydrophobic material layer. Therefore, peeling may occur at the portion with weak adhesion. According to an exemplary embodiment, the hydrophilic material layer 4052 can change the hydrophobic surface to hydrophilic to enhance the adhesion of the first bonding layer 4053, thereby preventing peeling.

[0601] The hydrophilic material layer 4052 can also be formed by depositing, for example, SiO2 on the surface of the support substrate 4051, or can be formed by treating the surface of the support substrate 4051 with plasma to modify the surface. The surface modification layer increases the surface energy, thereby converting the hydrophobic property into a hydrophilic property. In the case where the second insulating layer 4028 has a hydrophobic property, the hydrophilic material layer can also be provided on the second insulating layer 4028, and the first bonding layer 4052 can be in contact with the hydrophilic material layer on the second insulating layer 4028.

[0602] The second bonding layer 4055 bonds the second LED stack 4033 to the first LED stack 4023. The second bonding layer 4055 may be disposed between the first LED stack 4023 and the first color filter 4037 and may be in contact with the first color filter 4037. The second bonding layer 4055 may transmit light generated in the first LED stack 4023. A hydrophilic material layer 4054 may be disposed at an interface between the first LED stack 4023 and the second bonding layer 4055. The first conductive semiconductor layer 4023a of the first LED stack 4023 generally exhibits hydrophobic properties. Therefore, when the second bonding layer 4055 is in direct contact with the first conductive semiconductor layer 4023a, delamination is likely to occur at the interface between the second bonding layer 4055 and the first conductive semiconductor layer 4023a.

[0603] The hydrophilic material layer 4054 according to an exemplary embodiment changes the surface of the first LED stack 4023 from having a hydrophobic property to having a hydrophilic property, thereby improving the adhesion of the second bonding layer 4055, thereby reducing or preventing the occurrence of peeling. The hydrophilic material layer 4054 can be formed by depositing SiO2 or modifying the surface of the first LED stack 4023 using plasma as described above.

[0604] The surface layer of the first color filter 4037 in contact with the second bonding layer 4055 may be a hydrophilic material layer (e.g., SiO 2 ). In the case where the surface layer of the first color filter 4037 is not hydrophilic, a hydrophilic material layer may be formed on the first color filter 4037, and the second bonding layer 4055 may be in contact with the hydrophilic material layer.

[0605] The third bonding layer 4057 bonds the third LED stack 4043 to the second LED stack 4033. The third bonding layer 4057 may be disposed between the second LED stack 4033 and the second color filter 4047 and may be in contact with 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 may be disposed at an interface between the second LED stack 4033 and the third bonding layer 4057. The second LED stack 4033 may exhibit a hydrophobic property, and as a result, when the third bonding layer 4057 is in direct contact with the second LED stack 4033, delamination is likely to occur at the interface between the third bonding layer 4057 and the second LED stack 4033.

[0606] The hydrophilic material layer 4056 according to the exemplary embodiment changes the surface of the second LED stack 4033 from hydrophobic to hydrophilic, thereby improving the adhesion of the third bonding layer 4057 and preventing the occurrence of peeling. The hydrophilic material layer 4056 can be formed by depositing SiO2 or modifying the surface of the second LED stack 4033 using plasma as described above.

[0607] The surface layer of the second color filter 4047 in contact with the third bonding layer 4057 may be a hydrophilic material layer (e.g., SiO 2 ). If the surface layer of the second color filter 4047 is not hydrophilic, a hydrophilic material layer may be formed on the second color filter 4047, and the third bonding layer 4057 may be in contact with the hydrophilic material layer.

[0608] The first bonding layer 4053, the second bonding layer 4055, and the third bonding layer 4057 may be formed of a light-transmitting SOC, but are not limited thereto, and other transparent organic material layers or transparent inorganic material layers may be used. Examples of organic material layers may include SU8, poly(methyl methacrylate) (PMMA), polyimide, polyparaxylene, benzocyclobutene (BCB), etc. Examples of inorganic material layers may include Al2O3, SiO2, SiN x The organic material layer can be bonded under high vacuum and high pressure, and the inorganic material layer can be bonded by flattening the surface using, for example, chemical mechanical polishing, changing the surface energy using plasma, etc., and then utilizing the changed surface energy.

[0609] Figures 73A to 73F is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack 4000 for a display according to an exemplary embodiment.

[0610] Reference Figure 73AFirst, 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 conductive semiconductor layer 4023a, an active layer, and a second conductive semiconductor layer 4023b.

[0611] Next, the second conductive type semiconductor layer 4023b is partially removed to expose the first conductive type semiconductor layer 4023a. Figure 73A Only one pixel region is shown, but the first conductive type semiconductor layer 4023a is partially exposed for each pixel region.

[0612] A 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, a photoresist is applied thereto, and a photoresist pattern is formed by photolithography and development. Next, the SiO2 can be patterned using the photoresist pattern as an etching mask to form the first insulating layer 4027 having openings therein. One of the openings in the first insulating layer 4027 can be provided on the first conductive semiconductor layer 4023a, and the other opening can be provided on the second conductive semiconductor layer 4023b.

[0613] Thereafter, an ohmic contact layer 4025a and an ohmic electrode 4026 are formed in the opening of the first insulating layer 4027. The ohmic contact layer 4025a and the ohmic electrode 4026 may be formed using a lift-off technique. The ohmic contact layer 4025a may be formed first, and then the ohmic electrode 4026 may be formed, or vice versa. In addition, according to an exemplary embodiment, the ohmic electrode 4026 and the ohmic contact layer 4025a may be formed simultaneously from the same material.

[0614] After forming the ohmic contact layer 4025a, a reflective layer 4025b is formed to cover the ohmic contact layer 4025a and the first insulating layer 4027. The reflective layer 4025b can be formed using a lift-off technique. The reflective layer 4025b can cover a portion of the ohmic contact layer 4025a, or can substantially cover 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.

[0615] The reflective electrode 4025 may be in ohmic contact with the p-type semiconductor layer of the first LED stack 4023 and thus may be referred to as a first p-type reflective electrode 4025. The reflective electrode 4025 is spaced apart from the ohmic electrode 4026 and thus electrically insulated from the first conductive type semiconductor layer 4023a.

[0616] A second insulating layer 4028 is formed to cover the reflective electrode 4025 and to have an opening exposing the ohmic electrode 4026. The second insulating layer 4028 may be formed of, for example, SiO2 or SOG.

[0617] Then, 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 of the second insulating layer 4028, and is thus electrically connected to the first conductive type semiconductor layer 4023a.

[0618] Although the interconnection line 4029 is Figure 73A 4028 is shown as covering the entire surface of the second insulating layer 4028 , but the interconnection line 4029 may be partially provided on the second insulating layer 4028 , and the upper surface of the second insulating layer 4028 may be exposed around the interconnection line 4029 .

[0619] Although the illustrated exemplary embodiment shows one pixel region, the first LED stack 4023 disposed on the substrate 4021 may cover a plurality of pixel regions, and the interconnection line 4029 may be commonly connected to the ohmic electrodes 4026 formed on the plurality of regions. In addition, a plurality of interconnection lines 4029 may be formed on the substrate 4021.

[0620] Reference Figure 73B A second LED stack 4033 is grown on a second substrate 4031, and a second p-type 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 between the first-conductivity-type semiconductor layer 4033a and the second-conductivity-type semiconductor layer 4033b. The active layer may include a GaInN well layer. The second substrate 4031 is a substrate on which a gallium nitride-based semiconductor layer may be grown, and is different from the first substrate 4021. The composition ratio of GaInN may be determined so that the second LED stack 4033 can emit green light. The second p-type transparent electrode 4035 is in ohmic contact with the second-conductivity-type semiconductor layer 4033b.

[0621] A first color filter 4037 may be formed on the second p transparent electrode 4035, and since its details are substantially the same as those of the reference Figure 72 The descriptions are the same, so detailed descriptions thereof will be omitted to avoid redundancy.

[0622] Reference Figure 73CA third LED stack 4043 is grown on a third substrate 4041, and a third p-type 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 between the first-conductivity-type semiconductor layer 4043a and the second-conductivity-type semiconductor layer 4043b. The active layer may include a GaInN well layer. The third substrate 4041 is a substrate on which a gallium nitride-based semiconductor layer may be grown, and is different from the first substrate 4021. The composition ratio of GaInN may be determined so that the third LED stack 4043 emits blue light. The third p-type transparent electrode 4045 is in ohmic contact with the second-conductivity-type semiconductor layer 4043b.

[0623] Since the second color filter 4047 is Figure 72 The second color filter 4047 described is substantially the same, so its detailed description will be omitted to avoid redundancy.

[0624] 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 in which they are formed is not particularly limited.

[0625] Reference Figure 73D Next, the first LED stack 4023 is bonded to the support substrate 4051 through a first bonding layer 4053. A bonding material layer may be provided on the support substrate 4051 and the second insulating layer 4028 and may be bonded to each other to form the first bonding layer 4053. The interconnection line 4029 is provided to face the support substrate 4051.

[0626] Meanwhile, when the surface of the supporting substrate 4051 has a hydrophobic property, a hydrophilic material layer 4052 can be first formed on the supporting substrate 4051. The hydrophilic material layer 4052 can also be formed by depositing a layer of material such as SiO2 on the surface of the supporting substrate 4051, or by treating the surface of the supporting substrate 4051 with plasma or the like to increase the surface energy. The surface of the supporting substrate 4051 is modified by plasma treatment, and a surface-modified layer having a high surface energy can be formed on the surface of the supporting substrate 4051. The first bonding layer 4053 can be bonded to the hydrophilic material layer 4052, thereby improving the adhesion of the first bonding layer 4053.

[0627] The first substrate 4021 is removed from the first LED stack 4023 using a chemical etching technique. Thus, the first conductive semiconductor layer of the first LED stack 4023 is exposed on the top surface. The exposed surface of the first conductive semiconductor layer 4023a may be textured to improve light extraction efficiency, and a light extraction structure such as a rough surface may be formed on the surface of the first conductive semiconductor layer 4023a.

[0628] Reference Figure 73E , the second LED stack 4033 is bonded to the first LED stack 4023 through 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.

[0629] At the same time, before forming the second bonding layer 4055, a hydrophilic material layer 4054 can be first formed on the first LED stack 4023. The hydrophilic material layer 4054 changes the surface of the first LED stack 4023 from having a hydrophobic property to a hydrophilic property, thereby improving the adhesion of the second bonding layer 4055. The hydrophilic material layer 4054 can also be formed by depositing a layer of material 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 plasma treatment modifies the surface of the first LED stack 4023, and a surface-modified layer with high surface energy can be formed on the surface of the first LED stack 4023. The second bonding layer 4055 can be bonded to the hydrophilic material layer 4054, thereby improving the adhesion of the second bonding layer 4055.

[0630] The second substrate 4031 may be separated from the second LED stack 4033 using a technique such as laser lift-off or chemical lift-off. In addition, to improve light extraction, surface texturing may be used to form a rough surface on the exposed surface of the first conductive semiconductor layer 4033a.

[0631] Reference Figure 73F , a hydrophilic material layer 4056 may then be formed on the second LED stack 4033. The hydrophilic material layer 4056 changes the surface of the second LED stack 4033 into a hydrophilic property, thereby improving the adhesion of the third bonding layer 4057. The hydrophilic material layer 4056 may also be formed by depositing a layer of a material 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 a hydrophilic property, the hydrophilic material layer 4056 may be omitted.

[0632] Next, refer to Figure 72 and Figure 73C , the third LED stack 4043 is bonded to the second LED stack 4033 via a third bonding layer 4057. The second color filter 4047 is disposed to face 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.

[0633] The third substrate 4041 can be separated from the third LED stack 4043 using techniques such as laser lift-off or chemical lift-off. Figure 72 As shown in FIG, an LED stack for a display is provided in which the first conductive semiconductor layer 4043a of the third LED stack 4043 is exposed. In addition, a rough surface may be formed on the exposed surface of the first conductive semiconductor layer 4043a by surface texturing.

[0634] The stack of the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 disposed on the supporting substrate 4051 is patterned in units of pixels, and the patterned stacks are connected to each other using interconnection lines, thereby providing a display device. Hereinafter, a display device according to an exemplary embodiment will be described.

[0635] Figure 74 is a schematic circuit diagram of a display device according to an exemplary embodiment, Figure 75 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0636] Reference Figure 74 and Figure 75 , the display device according to the exemplary embodiment may be implemented to be driven in a passive matrix manner.

[0637] For example, due to the reference Figure 72 The LED stack for a display described herein has a structure in which a first LED stack 4023, a second LED stack 4033, and a third LED stack 4043 are stacked in a vertical direction, so 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.

[0638] exist Figure 74 and Figure 75In the embodiment, a pixel includes a first light-emitting diode R, a second light-emitting diode G, and a third light-emitting diode B, and each light-emitting diode corresponds to a sub-pixel. The anodes of the first light-emitting diode R, the second light-emitting diode G, and the third light-emitting diode B are connected to a common line (e.g., a data line), while their cathodes are connected to different lines (e.g., a scan line). For the first pixel, as an example, the anodes of the first light-emitting diode R, the second light-emitting diode G, and the third light-emitting diode B are commonly connected to the data line Vdata1, while their cathodes are connected to the 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 separately.

[0639] Furthermore, each of the light emitting diodes R, G, and B may be driven by using pulse width modulation or varying current intensity, thereby being able to adjust the brightness of each sub-pixel.

[0640] Refer again Figure 75 , through patterned reference Figure 72 The stack described above is used to form a plurality of patterns, and each pixel is connected to the reflective electrode 4025 and the interconnection lines 4071, 4073 and 4075. Figure 74 As shown in FIG, the reflective electrode 4025 can be used as a data line Vdata, and the interconnections 4071, 4073, and 4075 can be formed as scan lines. Here, the interconnection line 4075 can be formed by the interconnection line 4029. The reflective electrode 4025 can electrically connect the first conductive semiconductor layers 4023a, 4033a, and 4043a of the first LED stack 4023, the second stack 4033, and the third stack 4043 of the plurality of pixels, and the interconnection line 4029 can be arranged substantially perpendicular to the reflective electrode 4025 to electrically connect the first conductive semiconductor layers 4023a, 4033a, and 4043a of the plurality of pixels.

[0641] The pixels may be arranged in a matrix form, and the anodes of the light-emitting diodes R, G, and B of each pixel are commonly connected to the reflective electrode 4025, and their cathodes are each connected to interconnection lines 4071, 4073, and 4075 spaced apart from each other. Here, the interconnection lines 4071, 4073, and 4075 may serve as scan lines Vscan.

[0642] Figure 76 yes Figure 75 An enlarged plan view of one pixel of a display device, Figure 77 It is along Figure 76 A schematic cross-sectional view taken along line AA of FIG. Figure 78 It is along Figure 76 A schematic cross-sectional view taken along line BB of FIG.

[0643] Return to reference 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.

[0644] The third LED stack 4043 may have a rough surface 4043 r formed on its upper surface. The rough surface 4043 r may also be formed on the entire upper surface of the third LED stack 4043 or on a portion of the upper surface of the third LED stack 4043 .

[0645] The 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 substantially cover the entire upper surface of the third LED stack 4043. Optionally, the lower insulating layer 4061 according to an exemplary embodiment may include a light-reflecting layer or a light-absorbing layer to prevent light from propagating from the first LED stack 4023, the second stack 4033, and the third stack 4043 to the side surfaces. In this case, the lower insulating layer 4061 at least partially exposes the upper surface of the third LED stack 4043. The lower insulating layer 4061 may include, for example, a distributed Bragg reflector or a metal 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 can prevent light from being emitted to the outside of the pixel, thereby improving the contrast between pixels in the display device.

[0646] The lower insulating layer 4061 may have an opening 4061a exposing the upper surface of the third LED stack 4043, an opening 4061b exposing the upper surface of the second LED stack 4033, an opening 4061c exposing the third p-type transparent electrode 4045, an opening 4061d exposing the second p-type transparent electrode 4035, and an opening 4061e exposing the first p-type reflective electrode 4025. The upper surface of the first LED stack 4023 may not be exposed to the outside.

[0647] Interconnection lines 4071 and 4073 may be formed on the support substrate 4051 near the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043, and may be disposed on the lower insulating layer 4061 to be insulated from the first p-type reflective electrode 4025. Connectors 4077ab connect the second p-type transparent electrode 4035 and the third p-type transparent electrode 4045 to the reflective electrode 4025. Thus, 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.

[0648] The interconnection line 4075 or 4029 may be provided substantially perpendicular to the reflective electrode 4025 below the reflective electrode 4025 and connected to the ohmic electrode 4026, thereby being electrically connected to the first conductive type semiconductor layer 4023a. The ohmic electrode 4026 may be connected to the first conductive type semiconductor layer 4023a below the first LED stack 4023. Figure 76 As shown in FIG, the rough surface 4043 r of the third LED stack 4043 is disposed outside the lower region thereof, and thus light loss can be reduced.

[0649] The connector 4071 a connects the upper surface of the third LED stack 4043 to the interconnection line 4071 , and the connector 4073 a connects the upper surface of the second LED stack 4033 to the interconnection line 4073 .

[0650] An upper insulating layer 4081 may be provided on the interconnections 4071, 4073 and the lower insulating layer 4061 to protect the interconnections 4071, 4073, and 4075. The upper insulating layer 4081 may have openings exposing the interconnections 4071, 4073, and 4075, and bonding wiring or the like may be connected to the interconnections 4071, 4073, and 4075 through the openings.

[0651] According to an exemplary embodiment, the anodes of the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 are electrically connected in common to the reflective electrode 4025, and their cathodes are electrically connected to the interconnection wires 4071, 4073, and 4075, respectively. Therefore, the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043 can be driven independently. However, the inventive concept is not limited thereto, and the connection of the electrodes and the wiring can be variously modified.

[0652] Figures 79A to 79H is a schematic plan view for describing a method for manufacturing a display device according to an exemplary embodiment. Figure 76 The pixel method.

[0653] First, prepare as reference Figure 72 A light emitting diode stack 4000 is described.

[0654] Next, refer to Figure 79A A rough surface 4043r may be formed on the upper surface of the third LED stack 4043. The rough surface 4043r may be formed corresponding to each pixel region on the upper surface of the third LED stack 4043. The rough surface 4043r may be formed using a chemical etching technique (e.g., using a photo-enhanced chemical etching (PEC) technique).

[0655] Considering the area where the third LED stack 4043 will be etched in the future, a roughened surface 4043r may be formed locally within each pixel region. Specifically, the roughened surface 4043r may be formed such that the ohmic electrode 4026 is disposed outside the roughened surface 4043r. However, the inventive concept is not limited thereto, and the roughened surface 4043r may be formed substantially over the entire upper surface of the third LED stack 4043.

[0656] Reference Figure 79B Then, the peripheral area of ​​the third LED stack 4043 is etched in each pixel region to expose the third p transparent electrode 4045. The third LED stack 4043 can remain substantially rectangular or square in shape as shown, but at least two recesses can be formed along the edge. In addition, as shown, one recess can be formed larger than the other.

[0657] Reference Figure 79C Then, except for a portion of the third p transparent electrode 4045 exposed in the relatively large recess, the exposed third p transparent electrode 4045 is removed, thereby exposing the upper surface of the second LED stack 4033. The upper surface of the second LED stack 4033 is exposed around the third LED stack 4043 and also exposed in another recess. The region where the third p transparent electrode 4045 is exposed and the region where the second LED stack 4033 is exposed are formed in the relatively large recess.

[0658] Reference Figure 79D , except for the second LED stack 4033 formed in the relatively small recess, the second LED stack 4033 exposed in the remaining area is removed, thereby exposing the second p transparent electrode 4035. The second p transparent electrode is exposed around the third LED stack 4043, and the second p transparent electrode 4035 is also exposed in the relatively large recess.

[0659] Reference Figure 79E Then, the second p transparent electrode 4035 exposed around the third LED stack 4043 is removed except for the second p transparent electrode 4035 exposed in the relatively large recess, thereby exposing the upper surface of the first LED stack 4023.

[0660] Reference Figure 79FContinuing to remove the first LED stack 4023 exposed around the third LED stack 4043, and removing the first insulating layer 4027, the reflective electrode 4025 is exposed. Thus, the reflective electrode 4025 is exposed around the third LED stack 4043. The exposed reflective electrode 4025 is patterned to have a substantially elongated shape in the vertical direction, thereby forming a linear interconnection line. The patterned reflective electrode 4025 is arranged vertically for a plurality of pixel regions and is spaced apart from adjacent pixels in the horizontal direction.

[0661] In the exemplary embodiment shown, the reflective electrode 4025 is described as being patterned after the first LED stack 4023 is removed. However, when the reflective electrode 4025 is formed on the substrate 4021, the reflective electrode 4025 may be pre-formed to have a patterned shape. In this case, it is not necessary to pattern the reflective electrode 4025 after the first LED stack 4023 is removed.

[0662] By patterning the reflective electrode 4025 , the second insulating layer 4028 may be exposed. The interconnection line 4029 is provided perpendicular to the reflective electrode 4025 and is insulated from the reflective electrode 4025 by the second insulating layer 4028 .

[0663] Reference Figure 79G , then, a lower insulating layer 4061 is formed to cover the pixel. The lower insulating layer 4061 covers the reflective electrode 4025 and covers the side surfaces of the first stack 4023, the second stack 4033, and the third stack 4043. In addition, the lower insulating layer 4061 can at least partially cover the upper surface of the third LED stack 4043. In the case where the lower insulating layer 4061 is a transparent layer such as SiO2, the lower insulating layer 4061 can also substantially cover the entire upper surface of the third LED stack 4043. Alternatively, the lower insulating layer 4061 can further include a reflective layer or a light absorbing layer. In this case, the lower insulating layer 4061 at least partially exposes the upper surface of the third LED stack 4043, allowing light to be emitted to the outside.

[0664] The lower insulating layer 4061 may have an opening 4061a exposing the third LED stack 4043, an opening 4061b exposing 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 reflective electrode 4025. One or more openings 4061e exposing the reflective electrode 4025 may be formed.

[0665] Reference Figure 79HThen, interconnects 4071 and 4073 and connectors 4071a, 4073a, and 4077ab are formed using a lift-off technique. Interconnects 4071 and 4073 are insulated from reflective electrode 4025 by lower insulating layer 4061. Connector 4071a electrically connects third LED stack 4043 to interconnect 4071, and connector 4073a connects second LED stack 4033 to interconnect 4073. Connector 4077ab electrically connects third p-type transparent electrode 4045 and second p-type transparent electrode 4035 to first p-type reflective electrode 4025.

[0666] The interconnection lines 4071 and 4073 may be disposed substantially perpendicular to the reflective electrode 4025 and may connect a plurality of pixels to each other.

[0667] Next, an upper insulating layer 4081 covers interconnects 4071 and 4073 and connectors 4071a, 4073a, and 4077ab. Upper insulating layer 4081 may also substantially cover the entire upper surface of third LED stack 4043. Upper insulating layer 4081 may be formed, for example, of a silicon oxide film or a silicon nitride film and may further include a distributed Bragg reflector. Furthermore, upper insulating layer 4081 may include a transparent insulating film and a reflective metal layer, or a multilayer organic reflective layer thereon for reflecting light, or may include a light-absorbing layer such as a black epoxy resin to block light.

[0668] In the case where the upper insulating layer 4081 reflects or blocks light, in order to emit light to the outside, it is necessary to at least partially expose the upper surface of the third LED stack 4043. At the same time, in order to allow electrical connection from the outside, the upper insulating layer 4081 is partially removed, thereby partially exposing the interconnection lines 4071, 4073, and 4075. Alternatively, the upper insulating layer 4081 may be omitted.

[0669] When the upper insulating layer 4081 is formed, a Figure 76 In addition, as Figure 75 As shown in , a plurality of pixels may be formed on a supporting substrate 4051 , and those pixels may be connected to each other through a first p-type reflective electrode 4025 and interconnections 4071 , 4073 , and 4075 , and may be driven in a passive matrix manner.

[0670] In the illustrated exemplary embodiment, a method for manufacturing a display device that can be driven in a passive matrix manner is described, but the inventive concept is not limited thereto and includes Figure 72 The display device of the light emitting diode stack shown in FIG. 1 may be configured to be driven in various ways.

[0671] For example, it is described that the interconnection lines 4071 and 4073 are formed together on the lower insulating layer 4061 , but the interconnection line 4071 may be formed on the lower insulating layer 4061 and the interconnection line 4073 may be additionally formed on the upper insulating layer 4081 .

[0672] At the same time, Figure 72 In the embodiment of the present invention, the reflective electrode 4025, the second p-type transparent electrode 4035, and the third p-type transparent electrode 4045 are described as being in ohmic contact with the second conductive type semiconductor layers 4023b, 4033b, and 4043b of the first LED stack 4023, the second LED stack 4033, and the third LED stack 4043, respectively. Furthermore, the ohmic electrode 4026 is described as being in ohmic contact with the first conductive type semiconductor layer 4023a of the first LED stack 4023. However, ohmic contact layers are not separately provided for the first conductive type semiconductor layers 4033a and 4043a of the second LED stack 4033 and the third LED stack 4043. When the pixel size is as small as 200 microns or less according to some exemplary embodiments, even without forming a separate ohmic contact layer in the n-type first conductive type semiconductor layers 4033a and 4043a, there is no difficulty in current dispersion. However, for current dispersion, a transparent electrode layer may be provided on the n-type semiconductor layer of the second LED stack 4033 and the third LED stack 4043.

[0673] According to an exemplary embodiment, multiple pixels can be formed at the wafer level using the light-emitting diode stack 4000 for a display, thereby avoiding the step of individually mounting light-emitting diodes. In addition, since the light-emitting diode stack has a structure in whi...

Claims

1. A display device, comprising: A thin film transistor (TFT) substrate having electrode pads thereon; A first LED stack, located on the TFT substrate; A second LED stack, located on the first LED stack; A third LED stack, located on the second LED stack; a first ohmic electrode, located between the TFT substrate and the first LED stack and in contact with a lower surface of the first LED stack; A second ohmic electrode is disposed between the first LED stack and the second LED stack and is in ohmic contact with a lower surface of the second LED stack; a third ohmic electrode disposed between the second LED stack and the third LED stack and in ohmic contact with a lower surface of the third LED stack; as well as a connecting member electrically connecting the first LED stack to the third LED stack to the electrode pad of the TFT substrate, Wherein, the connecting piece comprises: a 1-1 connecting member, electrically connecting the first ohmic electrode to one of the electrode pads on the TFT substrate; A 2-1 connecting member, used for electrically connecting the second ohmic electrode to one of the electrode pads on the TFT substrate; A 3-1 connecting member is used to electrically connect the third ohmic electrode to one of the electrode pads on the TFT substrate, The 1-1th connecting member is in contact with the first ohmic electrode on the lower surface side of the first LED stack, The 2-1st connecting member is in contact with the second ohmic electrode on the lower surface side of the second LED stack, The 3-1st connecting member is in contact with the third ohmic electrode on the lower surface side of the third LED stack, The 1-1st connecting member, the 2-1st connecting member and the 3-1st connecting member are electrically connected to one of the electrode pads on the TFT substrate. wherein the first LED stack, the second LED stack, and the third LED stack can be driven independently, The light generated from the first LED stack is emitted to the outside through the second LED stack and the third LED stack, The light generated from the second LED stack is emitted to the outside through the third LED stack.

2. The display device according to claim 1, wherein: The first LED stack, the second LED stack, and the third LED stack emit red light, green light, and blue light, respectively.

3. The display device according to claim 1, wherein: The connecting member includes: a 1-2 connecting member electrically connecting an upper surface of the first LED stack and one of the electrode pads on the TFT substrate.

4. The display device according to claim 3, further comprising: in, The connecting piece also includes: a 2-2 connecting member, for electrically connecting an upper surface of the second LED stack to one of the electrode pads on the TFT substrate; The 3-2 connecting member is used to electrically connect the upper surface of the third LED stack to one of the electrode pads on the TFT substrate.

5. The display device according to claim 4, wherein: The 1-2nd connecting member contacts the upper surface of the first LED stack, The 2-2 connecting member contacts the upper surface of the second LED stack, The 3-2nd connecting member contacts an upper surface of the third LED stack.

6. The display device according to claim 5, wherein: The connector further includes an intermediate connector for electrically connecting the 2-1st connector, the 2-2nd connector, the 3-1st connector, and the 3-2nd connector to the electrode pad.

7. The display device according to claim 6, wherein: The connecting members respectively pass through the first LED stack members to at least one of the third LED stack members.

8. The display device according to claim 4, wherein: The 1-2nd connector, the 2-2nd connector, and the 3-2nd connector are electrically connected to different electrode pads.

9. The display device according to claim 8, wherein: The 1-1 connecting member, the 2-1 connecting member and the 3-1 connecting member are stacked in a vertical direction, The 1-2nd connecting member, the 2-2nd connecting member, and the 3-2nd connecting member are spaced apart from each other in a vertical direction and a horizontal direction.

10. The display device according to claim 4, wherein: The 1-1 connecting member, the 2-1 connecting member and the 3-1 connecting member are spaced apart from each other in the vertical direction and the horizontal direction, The 1-2nd connecting piece, the 2-2nd connecting piece and the 3-2nd connecting piece are stacked in a vertical direction.

11. The display device according to claim 1, further comprising: a first color filter interposed between the first LED stack and the second LED stack to transmit light generated from the first LED stack and to reflect light generated from the second LED stack; The second color filter, interposed between the second LED stack and the third LED stack, transmits the light generated from the first LED stack and the second LED stack and reflects the light generated from the third LED stack.

12. The display device according to claim 1, further comprising: A first bonding layer, disposed between the TFT substrate and the first LED stack; A second bonding layer, disposed between the first LED stack and the second LED stack; A third bonding layer is disposed between the second LED stack and the third LED stack. wherein the second bonding layer transmits light generated from the first LED stack, The third bonding layer transmits light generated from the first and second LED stacks.

13. The display device according to claim 1, wherein: The display device is driven in an active matrix manner.

14. A unit pixel, as a unit pixel of a display device that realizes an image by arranging a plurality of pixels, comprising: A thin film transistor (TFT) substrate having electrode pads thereon; A first LED stack, located on the TFT substrate; A second LED stack, located on the first LED stack; A third LED stack, located on the second LED stack; a first ohmic electrode, located between the TFT substrate and the first LED stack and in contact with a lower surface of the first LED stack; A second ohmic electrode is disposed between the first LED stack and the second LED stack and is in ohmic contact with a lower surface of the second LED stack; a third ohmic electrode disposed between the second LED stack and the third LED stack and in ohmic contact with a lower surface of the third LED stack; as well as a connection member including an electrode pad electrically connected to the first LED stack to the third LED stack, Wherein, the connecting piece comprises: a 1-1 connecting member, electrically connecting the first ohmic electrode to one of the electrode pads on the TFT substrate; A 2-1 connecting member, used for electrically connecting the second ohmic electrode to one of the electrode pads on the TFT substrate; A 3-1 connecting member is used to electrically connect the third ohmic electrode to one of the electrode pads on the TFT substrate, The 1-1th connecting member is in contact with the first ohmic electrode on the lower surface side of the first LED stack, The 2-1st connecting member is in contact with the second ohmic electrode on the lower surface side of the second LED stack, The 3-1st connecting member is in contact with the third ohmic electrode on the lower surface side of the third LED stack, The 1-1st connecting member, the 2-1st connecting member and the 3-1st connecting member are electrically connected to one of the electrode pads on the TFT substrate. The connecting member respectively passes through the first LED stack to at least one of the third LED stacks. The first LED stack, the second LED stack, and the third LED stack are independently drivable. The light generated from the first LED stack is emitted to the outside through the second LED stack and the third LED stack, The light generated from the second LED stack is emitted to the outside through the third LED stack.

15. The unit pixel according to claim 14, wherein: Anodes of the first to third LED stacks are electrically connected in common, and cathodes of the first to third LED stacks are electrically isolated from each other.

16. The unit pixel according to claim 14, wherein: The anodes of the first to third LED stacks are electrically isolated from each other, The cathodes of the first to third LED stacks are electrically connected in common to one another.

17. The unit pixel according to claim 14, wherein: The connecting members include connecting members stacked on each other.

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