LED stack for display and display device

Abstract

An LED stack for a display and a display device are disclosed. The LED stack includes: a supporting substrate; a first LED stack located on the supporting substrate; a second LED stack located on the first LED stack; a third LED stack located on the second LED stack; a first color filter disposed between the first LED stack and the second LED stack, and allowing light generated from the first LED stack to pass through and reflecting light generated from the second LED stack; and a second color filter disposed between the second LED stack and the third LED stack, and allowing light generated from the first LED stack and the second LED stack to pass through and reflecting light generated from the third LED stack, wherein light generated from the first LED stack is emitted toward the outside through the second LED stack and the third LED stack, and light generated from the second LED stack is emitted toward the outside through the third LED stack.

Description

Technical Field

[0001] This application is a divisional application of the invention patent application with the application date of November 27, 2018, application number 201880006547.9, and invention name “LED unit for display and display device having the LED unit”. Background Art

[0002] Light emitting diodes (LEDs) have been used as inorganic light sources in a wide range of fields, such as display devices, automobile lights, general lighting, etc. LEDs are rapidly replacing existing light sources due to their longer lifespan, lower power consumption, and faster response.

[0003] Typical light-emitting diodes have generally been used as backlight light sources in display devices. However, recently, micro-LEDs have been developed as next-generation displays that can realize images directly through light-emitting diodes.

[0004] Typically, a display device uses a mixture of blue, green, and red to create various colors. Thus, each pixel of the display device includes a blue sub-pixel, a green sub-pixel, and a red sub-pixel, and the colors of these sub-pixels determine the color of a particular pixel, and an image is created by combining these pixels.

[0005] In a micro-LED display, micro-LEDs are arranged on a two-dimensional plane to correspond to each pixel. Consequently, a large number of micro-LEDs, typically millions or tens of millions, are required on a single substrate. However, the small form factor of micro-LEDs, typically with a surface area of ​​approximately 10,000 square microns or less, can cause various problems during the manufacture of display devices. For example, handling micro-LEDs is difficult, making it difficult to mount them on display panels, especially when millions need to be transferred to manufacture a single display. Furthermore, once micro-LEDs are mounted on a display panel, replacing defective ones is difficult.

[0006] Furthermore, since the sub-pixels are arranged on a two-dimensional plane, the area occupied by a pixel comprising blue, green, and red sub-pixels is relatively large. Thus, arranging the sub-pixels within a limited area may require reducing the area of ​​each sub-pixel, which in turn may degrade the brightness of the sub-pixels due to the reduced light-emitting area.

[0007] 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 prior art. Summary of the Invention

[0008] Technical issues

[0009] Light emitting diodes constructed according to inventive principles and some exemplary embodiments and displays using the same can increase the light emitting area of ​​each LED sub-pixel without increasing the corresponding surface area of ​​the pixel region and without degrading display characteristics.

[0010] A light emitting diode and a display using the same constructed according to inventive principles and some exemplary embodiments have a sub-pixel structure in which at least two sub-pixels are vertically stacked, thereby reducing the surface area required to implement the display.

[0011] Light emitting diodes and displays using the same constructed according to the principles of the invention and some exemplary embodiments have independently drivable sub-pixels.

[0012] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments, and displays using the same, are particularly advantageous when constructed as micro-LEDs. For example, micro-LEDs constructed according to the principles of the invention and some exemplary embodiments can be manufactured simultaneously in multiples at the wafer level, eliminating the need for individually mounted micro-LEDs.

[0013] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments and displays using the same advantageously employ a partially reflective layer between the red LED stack and the substrate, and / or control the band gap of the semiconductor layer of each LED stack to control the brightness of each LED stack of a pixel using micro-LEDs.

[0014] 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.

[0015] Technical Solution

[0016] According to an embodiment of the present invention, a light-emitting diode stack for a display includes: a supporting substrate; a first LED stack located on the supporting substrate; a second LED stack located on the first LED stack; a third LED stack located on the second LED stack; a first color filter placed between the first LED stack and the second LED stack, allowing light generated from the first LED stack to pass through and reflecting light generated from the second LED stack; and a second color filter placed between the second LED stack and the third LED stack, allowing light generated from the first LED stack and the second LED stack to pass through and reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted toward the outside through the second LED stack and the third LED stack, and the light generated from the second LED stack is emitted toward the outside through the third LED stack.

[0017] According to another embodiment of the present invention, a display device includes a plurality of pixels arranged on a supporting substrate, wherein each pixel includes: a first LED stack located on the supporting substrate; a second LED stack located on the first LED stack; a third LED stack located on the second LED stack; a first color filter placed between the first LED stack and the second LED stack, and allowing light generated from the first LED stack to pass through and reflecting light generated from the second LED stack; and a second color filter placed between the second LED stack and the third LED stack, and allowing light generated from the first LED stack and the second LED stack to pass through and reflecting light generated from the third LED stack, wherein the light generated from the first LED stack is emitted toward the outside through the second LED stack and the third LED stack, and the light generated from the second LED stack is emitted toward the outside through the third LED stack.

[0018] According to an exemplary embodiment, a light emitting diode (LED) stack for a display includes: a supporting substrate; a first LED subunit disposed on the supporting substrate; a second LED subunit disposed on the first LED subunit; a third LED subunit disposed on the second LED subunit; a first color filter disposed between the first LED subunit and the second LED subunit and configured to transmit light generated in the first LED subunit and reflect light generated in the second LED subunit; and a second color filter disposed between the second LED subunit and the third LED subunit and configured to transmit light generated in the first LED subunit and the second LED subunit and reflect light generated in the third LED subunit, wherein the second LED subunit and the third LED subunit are configured to transmit light generated in the first LED subunit, and the third LED subunit is configured to transmit light generated in the second LED subunit.

[0019] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include a first LED stack, a second LED stack, and a third LED stack, respectively.

[0020] The LED stack may include micro-LEDs having a surface area of ​​less than about 10,000 μm 2 .

[0021] The second and third LED subunits may be configured to transmit light generated in the first LED subunit outside the micro LED stack, and the third LED subunit may be configured to transmit light generated in the second LED subunit outside the micro LED stack.

[0022] The first LED stack, the second LED stack, and the third LED stack may be configured to emit red light, green light, and blue light, respectively.

[0023] The first color filter and the second color filter may respectively include at least one of a low-pass filter, a band-pass filter, and a band-stop filter.

[0024] The first and second color filters may include distributed Bragg reflectors.

[0025] The LED stack for a display may also include: a first bonding layer positioned between the supporting substrate and the first LED stack; a second bonding layer positioned between the first LED stack and the first color filter; and a third bonding layer positioned between the second LED stack and the second color filter, wherein the second bonding layer is configured to transmit light generated in the first LED stack, and the third bonding layer is configured to transmit light generated in the first LED stack and the second LED stack.

[0026] The first bonding layer, the second bonding layer, and the third bonding layer may include at least one of a transparent inorganic insulating film, a transparent organic insulating film, and a transparent conductive thin film.

[0027] The LED stack for a display may further include: a first reflective electrode, disposed between the first bonding layer and the first LED stack, and in ohmic contact with the p-type semiconductor layer of the first LED stack; a second transparent electrode, disposed between the first color filter and the second LED stack, and in ohmic contact with the p-type semiconductor layer of the second LED stack; and a third transparent electrode, disposed between the second color filter and the third LED stack, and in ohmic contact with the p-type semiconductor layer of the third LED stack, wherein the second transparent electrode and the third transparent electrode are configured to transmit light generated in the first LED stack to the outside, and the third transparent electrode is configured to transmit light generated in the second LED stack to the outside.

[0028] The second bonding layer may contact the n-type semiconductor layer of the first LED stack, and the third bonding layer may contact the n-type semiconductor layer of the second LED stack.

[0029] The LED stack for a display may also include: a first bonding layer positioned between the supporting substrate and the first LED stack; a second bonding layer positioned between the first color filter and the second LED stack; and a third bonding layer positioned between the second LED stack and the second color filter, wherein the second bonding layer and the third bonding layer are constructed to transmit light generated in the first LED stack and the second LED stack.

[0030] The LED stack for a display may further include: a first reflective electrode, disposed between the first bonding layer and the first LED stack, and in ohmic contact with the n-type semiconductor layer of the first LED stack; a first transparent electrode, disposed between the first LED stack and the first color filter, and in ohmic contact with the p-type semiconductor layer of the first LED stack; a second transparent electrode, disposed between the second LED stack and the third bonding layer, and in ohmic contact with the p-type semiconductor layer of the second LED stack; and a third transparent electrode, disposed between the second color filter and the third LED stack, and in ohmic contact with the p-type semiconductor layer of the third LED stack; wherein the first transparent electrode, the second transparent electrode, and the third transparent electrode are configured to transmit light generated in the first LED stack to the outside, and the second transparent electrode and the third transparent electrode are configured to transmit light generated in the second LED stack to the outside.

[0031] The LED stack for a display may further include a second reflective electrode disposed between the second bonding layer and the second LED stack, wherein the second transparent electrode makes ohmic contact with the n-type semiconductor layer of the second LED stack.

[0032] A display device may include a plurality of pixels arranged on a supporting substrate, wherein at least some of the pixels include the LED stack according to example embodiments.

[0033] Each of the first LED stack, the second LED stack, and the third LED stack may include a p-type semiconductor layer and an n-type semiconductor layer, the p-type semiconductor layer of each pixel may be electrically connected to a common line, and the n-type semiconductor layer of each pixel may be electrically connected to different lines from each other.

[0034] The common lines may include data lines, and the different lines may include scan lines.

[0035] The display device may further include a lower insulating layer covering side surfaces of the first, second, and third LED stacks, wherein the lower insulating layer has an opening exposing a portion of the first, second, and third LED stacks.

[0036] The lower insulating layer may include a distributed Bragg reflector configured to reflect red light, green light, and blue light.

[0037] The display device may further include a reflective electrode disposed between the support substrate and the first LED stack, wherein the reflective electrode includes a common line continuously disposed for the plurality of pixels.

[0038] The display device may further include a plurality of reflective electrodes disposed between the support substrate and the first LED stack, wherein each reflective electrode is disposed within a respective pixel region.

[0039] The third LED stack may include a roughened surface region on an upper surface thereof.

[0040] The first LED stack, the second LED stack, and the third LED stack of each pixel may be driven independently.

[0041] According to an exemplary embodiment, an LED pixel for a display includes: a first LED subunit having a first surface and a second surface; a second LED subunit arranged on a portion of the first surface of the first LED subunit; a third LED subunit arranged on a portion of the second LED subunit; a reflective electrode arranged on the second surface of the first LED subunit; a second transparent electrode arranged between the second LED subunit and the third LED subunit and in ohmic contact with the upper surface of the second LED subunit; and a third transparent electrode in ohmic contact with the upper surface of the third LED subunit, wherein each of the first LED subunit, the second LED subunit and the third LED subunit includes an n-type semiconductor layer and a p-type semiconductor layer, each of the n-type semiconductor layers of the first LED subunit, the second LED subunit and the third LED subunit is electrically connected to the reflective electrode, and the first LED subunit, the second LED subunit and the third LED subunit are independently drivable.

[0042] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include a first LED stack, a second LED stack, and a third LED stack, respectively.

[0043] The LED pixels may include micro-LEDs having a surface area of ​​less than about 10,000 μm2.

[0044] The first LED stack, the second LED stack, and the third LED stack may be configured to emit red light, green light, and blue light, respectively.

[0045] A first portion of the light generated in the first LED stack may be configured to be emitted to the outside without passing through the second LED stack, a second portion of the light generated in the first LED stack may be configured to be emitted to the outside by being transmitted through the second LED stack and the second transparent electrode, a third portion of the light generated in the first LED stack may be configured to be emitted to the outside by being transmitted through the second LED stack, the second transparent electrode, the third LED stack and the third transparent electrode, a first portion of the light generated in the second LED stack may be configured to be emitted to the outside without passing through the third LED stack, and a second portion of the light generated in the second LED stack may be configured to be emitted to the outside by being transmitted through the third LED stack and the third transparent electrode.

[0046] Each of the p-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack can be disposed on a corresponding n-type semiconductor layer, the reflective electrode can be in ohmic contact with the n-type semiconductor layer of the first LED stack, and the second transparent electrode and the third transparent electrode can be in ohmic contact with the p-type semiconductor layer of the second LED stack and the p-type semiconductor layer of the third LED stack, respectively.

[0047] The LED pixel for the display may also include: a first color filter placed between the first LED stack and the second LED stack; and a second color filter placed between the second LED stack and the third LED stack, wherein the first color filter is configured to transmit light generated in the first LED stack and reflect light generated in the second LED stack, and the second color filter is configured to transmit light generated in the second LED stack and reflect light generated in the third LED stack.

[0048] The first color filter may be in contact with the n-type semiconductor layer of the second LED stack, and the second color filter may be in contact with the n-type semiconductor layer of the third LED stack.

[0049] The LED pixel for the display may also include: a first bonding layer positioned between the first LED stack and the first color filter; and a second bonding layer positioned between the second LED stack and the second color filter, wherein the second bonding layer is configured to transmit light generated in the first LED stack, and the third bonding layer is configured to transmit light generated in the second LED stack.

[0050] The LED pixel for the display may also include: a first ohmic electrode in ohmic contact with the p-type semiconductor layer of the first LED stack; a second ohmic electrode in contact with the n-type semiconductor layer of the second LED stack; a third ohmic electrode in contact with the n-type semiconductor layer of the third LED stack; a second current spreading layer disposed on the second transparent electrode; and a third current spreading layer disposed on the third transparent electrode, wherein the second ohmic electrode is disposed on an area of ​​the n-type semiconductor layer of the second LED stack that does not overlap with the third LED stack, and the second current spreading layer is disposed on the second transparent electrode.

[0051] The third ohmic electrode and the third current spreading layer may include the same material.

[0052] The second ohmic electrode, the second current spreading layer, the third ohmic electrode, and the third current spreading layer may include the same material.

[0053] The LED pixel for a display may further include a first current spreading layer disposed on the first ohmic electrode, wherein the first ohmic electrode is transparent, and the first current spreading layer, the second current spreading layer, and the third current spreading layer include the same material.

[0054] A display device may include a plurality of pixels arranged on a supporting substrate, wherein at least some of the pixels include LED pixels according to example embodiments.

[0055] Each of the p-type semiconductor layers of the first, second, and third LED stacks may be electrically connected to different lines from each other.

[0056] According to an exemplary embodiment, an LED stack for a display includes: a first LED subunit having a first surface and a second surface; a second LED subunit disposed on the first surface of the first LED subunit; a third LED subunit disposed on the second LED subunit; a reflective electrode disposed on the second surface of the first LED subunit and forming an ohmic contact with the first LED subunit; and an ohmic electrode placed between the first LED subunit and the second LED subunit and forming an ohmic contact with the first LED subunit, wherein the second LED subunit and the third LED subunit are configured to transmit light generated from the first LED subunit, and the third LED subunit is configured to transmit light generated from the second LED subunit.

[0057] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include a first LED stack, a second LED stack, and a third LED stack, respectively.

[0058] The LED stack may include micro-LEDs having a surface area of ​​less than about 10,000 μm 2 .

[0059] The reflective electrode and the ohmic electrode may have different reflectivities from each other.

[0060] The first LED stack, the second LED stack, and the third LED stack may be configured to emit red light, green light, and blue light, respectively.

[0061] The LED stack for a display may also include: a first color filter placed between the first LED stack and the second LED stack and configured to transmit light generated from the first LED stack and reflect light generated from the second LED stack; and a second color filter placed between the second LED stack and the third LED stack and configured to transmit light generated from the first LED stack and the second LED stack and reflect light generated from the third LED stack.

[0062] Each of the first and second color filters may include at least one of a low-pass filter, a band-pass filter, and a band-stop filter.

[0063] Each of the first and second color filters may include a distributed Bragg reflector.

[0064] The LED stack for a display may also include: a supporting substrate; a first bonding layer positioned between the supporting substrate and the first LED stack; a second bonding layer positioned between the first LED stack and the second LED stack; and a third bonding layer positioned between the second LED stack and the third LED stack, wherein the second bonding layer is configured to transmit light generated from the first LED stack, and the third bonding layer is configured to transmit light generated from the first LED stack and the second LED stack.

[0065] The first bonding layer may be adjacent to the reflective electrode, and the second bonding layer may be adjacent to the ohmic electrode.

[0066] The LED stack for a display may further include a second transparent electrode forming an ohmic contact with the p-type semiconductor layer of the second LED stack; and a third p transparent electrode forming an ohmic contact with the p-type semiconductor layer of the third LED stack.

[0067] The second bonding layer may be adjacent to the n-type semiconductor layer of the first LED stack, and the third bonding layer may be adjacent to the n-type semiconductor layer of the second LED stack.

[0068] The LED stack for a display may also include: a first color filter, which is placed between the first LED stack and the second LED stack and is configured to transmit light generated from the first LED stack and reflect light generated from the second LED stack; and a second color filter, which is placed between the second LED stack and the third LED stack and is configured to transmit light generated from the first LED stack and the second LED stack and reflect light generated from the third LED stack, wherein the first color filter is disposed on the second bonding layer and the second color filter is disposed on the third bonding layer.

[0069] A display device may include a plurality of pixels arranged on a supporting substrate, wherein at least some of the pixels include the LED stack according to example embodiments.

[0070] Each of the first LED stack, the second LED stack, and the third LED stack may include a p-type semiconductor layer and an n-type semiconductor layer, each of the p-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack may be electrically connected to a common line, and each of the n-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack may be electrically connected to different lines from each other.

[0071] The common lines may include data lines, and the different lines may include scan lines.

[0072] The display device may further include a lower insulating layer covering side surfaces of the first, second, and third LED stacks, the lower insulating layer including openings exposing the ohmic electrode, the reflective electrode, the second, and third LED stacks.

[0073] The lower insulating layer may include a distributed Bragg reflector configured to reflect red light, green light, and blue light.

[0074] The reflective electrode may include a common line and may be continuously provided for the plurality of pixels.

[0075] A reflective electrode may be provided in each pixel region.

[0076] According to an exemplary embodiment, an LED stack for a display includes: a first LED sub-unit configured to emit light of a first color; a second LED sub-unit disposed on the first LED stack and configured to emit light of a second color; and a third LED sub-unit disposed on at least one of the first LED sub-unit and the second LED sub-unit and configured to emit light of a third color, wherein the first LED sub-unit is configured to emit light that passes through the second LED sub-unit and the third LED sub-unit, and the second LED sub-unit is configured to emit light that passes through the third LED sub-unit.

[0077] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include a first LED stack, a second LED stack, and a third LED stack, respectively.

[0078] The LED stack may include micro-LEDs having a surface area of ​​less than about 10,000 μm 2 .

[0079] The wavelength of the light of the first color may be longer than the wavelength of the light of the second color, and the wavelength of the light of the second color may be longer than the wavelength of the light of the third color.

[0080] The first color light, the second color light, and the third color light may be red light, green light, and blue light, respectively.

[0081] The first LED stack may be configured to generate light when a portion of light of the second color is incident thereon, and the second LED stack may be configured to generate light when a portion of light of the third color is incident thereon.

[0082] The intensity of the second color light emitted to the outside can be at least about 10 times the intensity of the first color light emitted due to the second color light, and the intensity of the third color light emitted to the outside can be at least about 10 times the intensity of the second color light caused by the third color light.

[0083] The LED stack for a display may further include: a supporting substrate; a reflective electrode disposed between the first LED stack and the supporting substrate and forming an ohmic contact with the first LED stack; and an ohmic electrode disposed between the first LED stack and the second LED stack and forming an ohmic contact with the first LED stack.

[0084] The LED stack for a display may also include: a first bonding layer positioned between the supporting substrate and the first LED stack; a second bonding layer positioned between the first LED stack and the second LED stack; and a third bonding layer positioned between the second LED stack and the third LED stack, wherein the second bonding layer is configured to transmit light of a first color, and the third bonding layer is configured to transmit light of the first color and light of a second color.

[0085] The first bonding layer may be adjacent to the reflective electrode, and the second bonding layer is adjacent to the ohmic electrode.

[0086] The LED stack for a display may further include a second transparent electrode forming an ohmic contact with the p-type semiconductor layer of the second LED stack; and a third transparent electrode forming an ohmic contact with the p-type semiconductor layer of the third LED stack.

[0087] The second bonding layer may be adjacent to the n-type semiconductor layer of the first LED stack, and the third bonding layer is adjacent to the n-type semiconductor layer of the second LED stack.

[0088] A display device may include a plurality of pixels arranged on a supporting substrate, wherein at least some of the pixels include the LED stack according to example embodiments.

[0089] The first LED stack may have a first region, a second region, and a third region, the first region may not be overlapped by the second LED stack and the third LED stack in a plan view, the second region may be overlapped by the second LED stack and not overlapped by the third LED stack in a plan view, and the third region may be overlapped by both the second LED stack and the third LED stack in a plan view.

[0090] The first LED stack, the second LED stack, and the third LED stack may have substantially the same width as one another in a plan view.

[0091] In a plan view, a width of the first LED stack may be greater than a width of the second LED stack or a width of the third LED stack.

[0092] The display device may further include a lower insulating layer covering side surfaces of the first, second, and third LED stacks, wherein the lower insulating layer includes openings exposing the ohmic electrode, the reflective electrode, the second, and third LED stacks.

[0093] The lower insulating layer may include a distributed Bragg reflector configured to reflect red light, green light, and blue light.

[0094] Each of the first LED stack, the second LED stack, and the third LED stack may include a p-type semiconductor layer and an n-type semiconductor layer, and each of the p-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack may be electrically connected to a common line, and each of the n-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack may be electrically connected to different lines from each other.

[0095] The reflective electrode may include a common line and may be continuously provided for the plurality of pixels.

[0096] A reflective electrode may be provided in each pixel region.

[0097] The first LED stack, the second LED stack, and the third LED stack may be configured to be driven independently.

[0098] According to an exemplary embodiment, an LED pixel for a display includes: a substrate; a first LED subunit, which is arranged on the substrate; a second LED subunit, which is arranged on the first LED subunit; a third LED subunit, which is arranged on at least one of the first LED subunit and the second LED subunit; and a via hole located in the substrate, wherein each of the first LED subunit, the second LED subunit and the third LED subunit includes a first conductive semiconductor layer and a second conductive semiconductor layer, and each of the via holes is electrically connected to at least one of the first LED subunit, the second LED subunit and the third LED subunit.

[0099] The first LED sub-unit, the second LED sub-unit, and the third LED sub-unit may include a first LED stack, a second LED stack, and a third LED stack, respectively.

[0100] The LED pixels may include micro-LEDs having a surface area of ​​less than about 10,000 μm2.

[0101] The first LED stack, the second LED stack, and the third LED stack may be configured to emit light having different wavelengths from each other.

[0102] The first LED stack, the second LED stack, and the third LED stack may be configured to emit red light, green light, and blue light, respectively.

[0103] The substrate may include a GaAs substrate, and the first LED stack includes an AlGaInP-based semiconductor layer.

[0104] The LED pixel for a display may further include a distributed Bragg reflector disposed between the substrate and the first LED stack, wherein the distributed Bragg reflector may include a semiconductor layer.

[0105] The distributed Bragg reflector may include AlAs layers and AlGaAs layers alternately arranged with each other.

[0106] The LED pixel for a display may further include a first bonding layer disposed between the first LED stack and the second LED stack; and a second bonding layer disposed between the second LED stack and the third LED stack.

[0107] The LED pixel for the display may also include: a lower second ohmic electrode, placed between the first bonding layer and the second LED stack, and forming an ohmic contact with the second LED stack; and a lower third ohmic electrode, placed between the second bonding layer and the third LED stack, and forming an ohmic contact with the third LED stack.

[0108] Each of the lower second ohmic electrode and the lower third ohmic electrode may include a reflective layer.

[0109] The vias may include a first via, a second via, and a third via, the first via being electrically connected to the second conductive semiconductor layer of the first LED stack, the second via being electrically connected to the second conductive semiconductor layer of the second LED stack, and the third via being electrically connected to the second conductive semiconductor layer of the third LED stack.

[0110] The first conductive type semiconductor layer of the first LED stack, the first conductive type semiconductor layer of the second LED stack, and the first conductive type semiconductor layer of the third LED stack may be electrically connected to each other.

[0111] The LED pixel for the display may also include: an upper first ohmic electrode, contacting the first conductive semiconductor layer of the first LED stack; a lower first ohmic electrode, contacting the second conductive semiconductor layer of the first LED stack; an upper second ohmic electrode, contacting the first conductive semiconductor layer of the second LED stack; a lower second ohmic electrode, contacting the second conductive semiconductor layer of the second LED stack; an upper third ohmic electrode, contacting the first conductive semiconductor layer of the third LED stack; and a lower third ohmic electrode, contacting the second conductive semiconductor layer of the third LED stack, wherein the first via, the second via and the third via are electrically connected to the lower first ohmic electrode, the lower second ohmic electrode and the lower third ohmic electrode, respectively, and the upper first ohmic electrode, the upper second ohmic electrode and the upper third ohmic electrode are electrically connected to each other.

[0112] The LED pixel for a display may further include bonding pads disposed on a lower surface of the substrate, wherein the vias are connected to the bonding pads, respectively.

[0113] The bonding pads may include first bonding pads insulated from the substrate and at least one second bonding pad electrically connected to the substrate, and the vias may be electrically connected to the first bonding pads, respectively.

[0114] A display device may include a circuit board and a plurality of pixels arranged on the circuit board, wherein at least some of the pixels include LED pixels according to example embodiments.

[0115] The circuit board may include at least one of a passive circuit and an active circuit, and the via is electrically connected to the circuit board.

[0116] The substrate may be continuously provided for the plurality of pixels and grounded by being electrically connected to the circuit board.

[0117] The display device may further include electrode pads interposed between the substrate and the circuit board, wherein at least one of the electrode pads is electrically connected to the substrate, and the via is electrically connected to the circuit board through the electrode pad.

[0118] 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.

[0119] Beneficial effects

[0120] Light emitting diodes constructed according to inventive principles and some exemplary embodiments and displays using the same can increase the light emitting area of ​​each LED sub-pixel without increasing the corresponding surface area of ​​the pixel region and without degrading display characteristics.

[0121] A light emitting diode constructed according to inventive principles and some exemplary embodiments and a display using the same have a sub-pixel structure in which at least two sub-pixels are vertically stacked, thereby reducing a surface area required to implement the display.

[0122] Light emitting diodes and displays using the same constructed according to the principles of the invention and some exemplary embodiments have independently drivable sub-pixels.

[0123] Light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments, and displays using the same, are particularly advantageous when constructed as micro-LEDs. For example, micro-LEDs constructed according to the principles of the invention and some exemplary embodiments can be manufactured simultaneously in multiples at the wafer level, eliminating the need for individually mounted micro-LEDs.

[0124] It is advantageous for light-emitting diodes constructed according to the principles of the invention and some exemplary embodiments, and displays using the same, to employ a local reflective layer between the red LED stack and the substrate and / or to control the band gap of the semiconductor layer of each LED stack to control the brightness of each LED stack using micro-LEDs in a pixel. BRIEF DESCRIPTION OF THE DRAWINGS

[0125] The accompanying drawings illustrate exemplary embodiments of the invention and together with the description serve to explain the inventive concept. The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification.

[0126] Figure 1 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0127] Figure 2 is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0128] Figure 3 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0129] Figure 4 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0130] Figure 5 According to an exemplary embodiment Figure 4 An enlarged plan view of a pixel of a display device.

[0131] Figure 6 It is along Figure 5 A schematic cross-sectional view taken along line AA of FIG.

[0132] Figure 7 It is along Figure 5 A schematic cross-sectional view taken along line BB of FIG.

[0133] Figure 8A 、 Figure 8B 、 Figure 8C 、 Figure 8D 、 Figure 8E 、 Figure 8F 、 Figure 8G 、 Figure 8H 、 Figure 8I 、 Figure 8J and Figure 8K is a schematic plan view illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0134] Figure 9 is a schematic circuit diagram of a display device according to another exemplary embodiment.

[0135] Figure 10 is a schematic plan view of a pixel according to another exemplary embodiment.

[0136] Figure 11 is a schematic cross-sectional view of a light emitting diode stack for a display according to yet another exemplary embodiment.

[0137] Figure 12A 、 Figure 12B 、 Figure 12C 、 Figure 12D 、 Figure 12E and Figure 12F is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to still another exemplary embodiment.

[0138] Figure 13 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0139] Figure 14 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

[0140] Figure 15 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0141] Figure 16 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0142] Figure 17 According to an exemplary embodiment Figure 16 An enlarged plan view of a pixel of a display device.

[0143] Figure 18A According to an exemplary embodiment, Figure 17A schematic cross-sectional view taken along line AA of FIG.

[0144] Figure 18B According to an exemplary embodiment, Figure 17 A schematic cross-sectional view taken along line BB of FIG.

[0145] Figure 18C According to an exemplary embodiment, Figure 17 A schematic cross-sectional view taken along line CC of FIG.

[0146] Figure 18D According to an exemplary embodiment, Figure 17 Schematic cross-sectional view taken along line DD.

[0147] Figure 19A 、 Figure 19B 、 Figure 20A 、 Figure 20B 、 Figure 21A 、 Figure 21B 、 Figure 21C 、 Figure 22A 、 Figure 22B 、 Figure 22C 、 Figure 23A 、 Figure 23B 、 Figure 24A 、 Figure 24B 、 Figure 25A 、 Figure 25B 、 Figure 26A 、 Figure 26B 、 Figure 27A 、 Figure 27B 、 Figure 28A 、 Figure 28B 、 Figure 29A 、 Figure 29B 、 Figure 30A 、 Figure 30B 、 Figure 31 、 Figure 32A 、 Figure 32B and Figure 33 are schematic plan views and cross-sectional views illustrating a method of manufacturing a display apparatus according to an exemplary embodiment.

[0148] Figure 34 is a schematic cross-sectional view of a display device according to still another exemplary embodiment.

[0149] Figure 35 is a schematic circuit diagram of a display device according to still another exemplary embodiment.

[0150] Figure 36 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0151] 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.

[0152] Figure 38 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0153] Figure 39 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0154] Figure 40 According to an exemplary embodiment Figure 39 An enlarged plan view of a pixel of a display device.

[0155] Figure 41 It is along Figure 40 A schematic cross-sectional view taken along line AA of FIG.

[0156] Figure 42 It is along Figure 40 A schematic cross-sectional view taken along line BB of FIG.

[0157] 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.

[0158] Figure 44 is a schematic circuit diagram of a display device according to another exemplary embodiment.

[0159] Figure 45 is a schematic plan view of a display device according to another exemplary embodiment.

[0160] Figure 46 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0161] 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.

[0162] Figure 48is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0163] Figure 49 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0164] Figure 50 According to an exemplary embodiment Figure 49 An enlarged plan view of a pixel of a display device.

[0165] Figure 51 According to an exemplary embodiment, Figure 50 A schematic cross-sectional view taken along line AA of FIG.

[0166] Figure 52 According to an exemplary embodiment, Figure 50 A schematic cross-sectional view taken along line BB of FIG.

[0167] 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.

[0168] Figure 54 is a schematic circuit diagram of a display device according to another exemplary embodiment.

[0169] Figure 55 is a schematic plan view of a display device according to another exemplary embodiment.

[0170] Figure 56 is a schematic plan view of a display apparatus according to an exemplary embodiment.

[0171] Figure 57 is a cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

[0172] Figure 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0173] Figure 59A and Figure 59B 1 and 2 are respectively a top view and a bottom view of one pixel of a display device according to an exemplary embodiment.

[0174] Figure 60A It is along Figure 59A A schematic cross-sectional view taken along line AA of FIG.

[0175] Figure 60B According to an exemplary embodiment, Figure 59A A schematic cross-sectional view taken along line BB of FIG.

[0176] Figure 60C According to an exemplary embodiment, Figure 59A A schematic cross-sectional view taken along line CC of FIG.

[0177] Figure 60D According to an exemplary embodiment, Figure 59A Schematic cross-sectional view taken along line DD.

[0178] 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 cross-sectional views illustrating a method of manufacturing a display apparatus according to an exemplary embodiment.

[0179] Figure 69 is a cross-sectional view of a light emitting diode pixel for a display according to another exemplary embodiment.

[0180] Figure 70 is an enlarged top plan view of one pixel of a display device according to an exemplary embodiment.

[0181] Figure 71A and Figure 71B Along Figure 70 A cross-sectional view taken along line GG and line HH. DETAILED DESCRIPTION

[0182] 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 that are non-limiting examples of the apparatus or method using 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, well-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, configuration and characteristics of the exemplary embodiment may be used or implemented in another exemplary embodiment.

[0183] 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 different embodiments may be further combined, separated, interchanged and / or rearranged without departing from the inventive concept.

[0184] 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 or absence of cross hatching or shading does 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, the 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.

[0185] When an element such as a layer is referred to as being "on" another element or layer, "connected to" or "bound to" another element or layer, the element or layer 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" another element or layer, "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 intermediate elements. 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.

[0186] 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.

[0187] 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.

[0188] 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", "a(kind / person)" and "the(s)" 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 features, integral bodies, steps, operations, elements, components and / or their groups stated are indicated, but the presence or addition of one or more other features, integral bodies, steps, operations, elements, components and / or their groups is not excluded. It should also be noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms rather than as terms of degree, and as such, 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.

[0189] 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. Accordingly, the exemplary embodiments disclosed herein should not be construed as limited to the shapes of the specifically illustrated regions, but 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 regions of the device and, as such, are not necessarily intended to be limiting.

[0190] 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.

[0191] As used herein, a light emitting diode stack or light emitting diode according to exemplary embodiments may include a micro-LED having a surface area of ​​less than about 10,000 square micrometers (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.

[0192] Reference Figure 1The light emitting diode stack 100 for a display may include a supporting substrate 51, a first LED stack 23, a second LED stack 33, a third LED stack 43, a first p-reflective electrode 25, a second p-transparent electrode 35, a third p-transparent electrode 45, a first color filter 37, a second color filter 47, a first bonding layer 53, a second bonding layer 55, and a third bonding layer 57. As used in the exemplary embodiments disclosed herein, a light emitting diode stack may be referred to as a micro-LED (or a micro-LED stack).

[0193] The support substrate 51 supports the first LED stack 23, the second LED stack 33, and the third LED stack 43. The support substrate 51 may have a circuit on its surface or in its interior, but the inventive concept is not limited thereto. The support substrate 51 may include, for example, a Si substrate or a Ge substrate.

[0194] 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 disposed between the n-type semiconductor layer and the p-type semiconductor layer. The active layer may have a multi-quantum well structure.

[0195] For example, the first LED stack 23 may be an inorganic light-emitting diode that emits red light, the second LED stack 33 may be an inorganic light-emitting diode that emits green light, and the third LED stack 43 may be an inorganic light-emitting diode that emits blue light. The first LED stack 23 may include a GaInP base well layer, and the second and third LED stacks 33 and 43 may include a GaInN base well layer. However, the inventive concept is not limited thereto, and when the light-emitting diode stack 100 includes a micro-LED, the first LED stack 23 may emit any one of red, green, and blue light, and the second and third LED stacks 33 and 43 may emit different ones of red, green, and blue light, without adversely affecting operation or requiring a color filter due to its small form factor.

[0196] The top surface and the bottom surface of each of the first LED stack 23, the second LED stack 33, and the third LED stack 43 may include an n-type semiconductor layer and a p-type semiconductor layer. Figure 1 In the embodiment, the upper surface of each of the first LED stack 23, the second LED stack 33, and the third LED stack 43 is described as including an n-type semiconductor layer, and the lower surface thereof is described as including a p-type semiconductor layer. Since the upper surface of the third LED stack 43 is n-type, a rough surface can be formed on the upper surface of the third LED stack 43 by chemical etching. 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.

[0197] The first LED stack 23 is disposed closer to the supporting base 51, the second LED stack 33 is disposed on the first LED stack 23, and the third LED stack 43 is disposed on the second LED stack 33. Since the wavelength of light emitted by the first LED stack 23 is longer than the wavelengths of light emitted by the second LED stack 33 and the third LED stack 43, light generated in the first LED stack 23 can be emitted to the outside through the second LED stack 33 and the third LED stack 43. Furthermore, since the wavelength of light emitted by the second LED stack 33 is longer than the wavelength of light emitted by the third LED stack 43, light generated in the second LED stack 33 can be emitted to the outside through the third LED stack 43.

[0198] The first p-type reflective electrode 25 makes ohmic contact with the p-type semiconductor layer of the first LED stack 23 and can reflect light generated from the first LED stack 23. For example, the first p-type reflective electrode 25 may include Au-Ti, Au-Sn, etc. In addition, the first p-type reflective electrode 25 may include a diffusion barrier layer.

[0199] The second p transparent electrode 35 makes ohmic contact with the p-type semiconductor layer of the second LED stack 33. The second p transparent electrode 35 may include a metal layer or a conductive oxide layer that is transparent to red and green light.

[0200] The third p transparent electrode 45 makes ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third p transparent electrode 45 may include a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0201] The first p reflective electrode 25 , the second p transparent electrode 35 , and the third p transparent electrode 45 make ohmic contact with the p-type semiconductor layer of each LED stack 23 , 33 , and 43 , and may facilitate current spreading.

[0202] In addition, 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 transmits light generated in the first LED stack 23 and reflects light generated in the second LED stack 33. Furthermore, the second color filter 47 transmits light generated in the first and second LED stacks 23 and 33 and reflects light generated in the third LED stack 43. Therefore, light generated in the first LED stack 23 can be emitted to the outside through the second and third LED stacks 33 and 43, and light generated in the second LED stack 33 can be emitted to the outside through the third LED stack 43. Furthermore, light generated in the second LED stack 33 can be prevented from being incident on the first LED stack 23 and being lost, and light generated in the third LED stack 43 can be prevented from being incident on the second LED stack 33 and being lost. According to exemplary embodiments, the first color filter 37 may also reflect light generated in the third LED stack 43.

[0203] Each of the first color filter 37 and the second color filter 47 can be, for example, a low-pass filter that only passes a low-frequency region (e.g., a long-wave region), a band-pass filter that only passes a predetermined wavelength band, or a band-stop filter that only blocks a predetermined wavelength band. Specifically, the first color filter 37 and the second color filter 47 can include a distributed Bragg reflector (DBR). A distributed Bragg reflector can reflect light in a specific wavelength band (stop band) while transmitting light in another wavelength region. A distributed Bragg reflector can be formed by alternately stacking insulating layers with different refractive indices, and can be formed, for example, by alternately stacking TiO2 and SiO2. In addition, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of TiO2 and SiO2. A low-pass filter and a band-pass filter can also be formed by alternately stacking insulating layers with different refractive indices one on top of the other.

[0204] The first bonding layer 53 bonds the first LED stack 23 to the supporting substrate 51. Figure 1 As shown in FIG, the first p-reflective electrode 25 may be in contact with the first bonding layer 53. The first bonding layer 53 may be a light-transmitting layer or a light-impermeable layer. The first bonding layer 53 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film.

[0205] The second bonding layer 55 bonds the second LED stack 33 to the first LED stack 23. Figure 1, the second bonding layer 55 may be in contact with the first LED stack 23 and the first color filter 37. However, the inventive concept is not limited thereto, and a transparent conductive layer may be additionally provided on the first LED stack 23. The second bonding layer 55 transmits light generated in the first LED stack 23. The second bonding layer 55 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film, and may be formed of, for example, light-transmitting spin-on glass.

[0206] The third bonding layer 57 bonds the third LED stack 43 to the second LED stack 33. Figure 1 As shown in FIG, the third bonding layer 57 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 additionally provided on the second LED stack 33. The third bonding layer 57 transmits light generated in the first LED stack 23 and the second LED stack 33. The third bonding layer 57 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film, and may be formed of, for example, light-transmitting spin-on glass.

[0207] Figure 2 is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to an exemplary embodiment.

[0208] Reference Figure 2 First, the first LED stack 23 is grown on the first substrate 21 , and the first p-reflective electrode 25 is formed on the first LED stack 23 .

[0209] The first substrate 21 can be, for example, a GaAs substrate. Furthermore, the first LED stack 23 is formed as an AlGaInP-based semiconductor layer and includes an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The first p-type reflective electrode 25 makes ohmic contact with the p-type semiconductor layer of the first LED stack 23.

[0210] Furthermore, a second LED stack 33 is grown on a second substrate 31, and a second p-type transparent electrode 35 and a first color filter 37 are formed on the second LED stack 33. The second LED stack 33 is formed of a gallium nitride-based semiconductor layer and may include a GaInN well layer. The second substrate 31 is a substrate on which a gallium nitride-based semiconductor layer can be grown, and is different from the first substrate 21. The composition ratio of GaInN is determined so that the second LED stack 33 emits green light. The second p-type transparent electrode 35 is in ohmic contact with the p-type semiconductor layer of the second LED stack 33.

[0211] Furthermore, a third LED stack 43 is grown on a third substrate 41, and a third p-type transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 is formed of a gallium nitride-based semiconductor layer and may include a GaInN well layer. The third substrate 41 is a substrate on which a gallium nitride-based semiconductor layer can be grown, and is different from the first substrate 21. The composition ratio of GaInN is determined so that the third LED stack 43 emits blue light. Furthermore, the third p-type transparent electrode 45 is in ohmic contact with the p-type semiconductor layer of the third LED stack 43.

[0212] Figure 2 The first color filter 37 and the second color filter 47 are Figure 1 The described first color filter 37 and second color filter 47 are the same, and thus, detailed descriptions thereof will be omitted to avoid redundancy.

[0213] Reference Figure 1 and Figure 2 , the first LED stack 23 is bonded to the supporting substrate 51 via the first bonding layer 53. The first bonding layer 53 may be pre-placed on the supporting substrate 51, and then the first p-reflective electrode 25 may be bonded to the first bonding layer 53, facing the supporting substrate 51. In addition, the first substrate 21 is removed from the first LED stack 23 using a chemical etching technique.

[0214] Then, the second LED stack 33 is bonded to the first LED stack 23 via the second bonding layer 55. The first color filter 37 is bonded to the second bonding layer 55, facing the first LED stack 23. The second bonding layer 55 may be pre-placed on the first LED stack 23, and then the first color filter 37 may be positioned to face and bond to the second bonding layer 55. In addition, the second substrate 31 may be separated from the second LED stack 33 using techniques such as laser lift-off, chemical lift-off, and the like.

[0215] Then, the third LED stack 43 is bonded to the second LED stack 33 via the third bonding layer 57. The second color filter 47 is bonded to the third bonding layer 57 and faces the second LED stack 33. The third bonding layer 57 may be pre-set on the second LED stack 33, and then the second color filter 47 may be positioned to face and bond to the third bonding layer 57. In addition, the third substrate 41 may be separated from the third LED stack 43 using techniques such as laser lift-off, chemical lift-off, etc. In this way, a Figure 1 , wherein the n-type semiconductor layer of the third LED stack 43 is exposed.

[0216] The display device according to the exemplary embodiment can be formed by patterning the stack of the first LED stack 23, the second LED stack 33, and the third LED stack 43 provided on the supporting substrate 51 in units of pixels and connecting the LED stacks to each other through interconnections. Hereinafter, the display device according to the exemplary embodiment will be described.

[0217] Figure 3 is a schematic circuit diagram of a display device according to an exemplary embodiment. Figure 4 is a schematic plan view of a display apparatus according to an exemplary embodiment. Figure 5 According to an exemplary embodiment Figure 4 An enlarged plan view of a pixel of a display device. Figure 6 It is along Figure 5 A schematic cross-sectional view taken along line AA of FIG. Figure 7 It is along Figure 5 A schematic cross-sectional view taken along line BB of FIG.

[0218] Reference Figure 3 and Figure 4 , the display device according to the exemplary embodiment may be implemented to be driven in a passive matrix manner.

[0219] For example, refer to Figure 1 The described light-emitting diode stack for a display has a structure in which a first LED stack 23, a second LED stack 33, and a third LED stack 43 are stacked in a vertical direction, so that one pixel includes three types of light-emitting diodes R, G, and B. Here, the first light-emitting diode R corresponds to the first LED stack 23, the second light-emitting diode G corresponds to the second LED stack 33, and the third light-emitting diode B corresponds to the third LED stack 43.

[0220] exist Figure 3 and Figure 4 In the embodiment of the present invention, 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). More specifically, in the first pixel, 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 independently.

[0221] Furthermore, each of the light emitting diodes R, G, and B may be driven in a pulse width modulation scheme or by varying current intensity, thereby adjusting the brightness of each sub-pixel.

[0222] Reference Figure 4 , through patterned reference Figure 1 The LED stack described above is used to form a plurality of pixels, and each pixel is connected to the first p reflective electrode 25 and interconnection lines 71, 73 and 75. Figure 3 As shown in FIG, the first p reflective electrode 25 may be used as a data line Vdata, and the interconnection lines 71, 73, and 75 may be used as scan lines.

[0223] The pixels may be arranged in a matrix, with the anodes of the light-emitting diodes R, G, and B of each pixel being commonly connected to the first p-reflective electrode 25, and their cathodes being respectively connected to interconnection lines 71, 73, and 75 spaced apart from each other. The interconnection lines 71, 73, and 75 may be used as scan lines Vscan.

[0224] Reference Figures 4 to 7 , a portion of the first p reflective electrode 25, a portion of the upper surface of the first LED stack 23, a portion of the second p transparent electrode 35, a portion of the upper surface of the second LED stack 33, a portion of the third p transparent electrode 45 and the upper surface of the third LED stack 43 in each pixel are exposed to the outside.

[0225] The third LED stack 43 may have a rough surface 43a on its upper surface. The rough surface 43a may be formed on the entire upper surface of the third LED stack 43, or may be formed as shown in FIG. Figure 6 is shown formed on a portion of the upper surface of the third LED stack 43 .

[0226] The first insulating layer 61 may cover the side surfaces of each pixel. The first insulating layer 61 may be formed of a light-transmitting material such as SiO2. In this case, the first insulating layer 61 may cover the entire upper surface of the third LED stack 43. Alternatively, the first insulating layer 61 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first LED stack 23, the second LED stack 33, and the third LED stack 43. In this case, the first insulating layer 61 at least partially exposes the upper surface of the third LED stack 43.

[0227] The first insulating layer 61 may have an opening 61 a exposing the upper surface of the third LED stack 43 , an opening 61 b ​​exposing the upper surface of the second LED stack 33 , an opening 61 c exposing the upper surface of the first LED stack 23 (at the top of the LED stack 23 ). Figure 8H), an opening 61d exposing the third p transparent electrode 45, an opening 61e exposing the second p transparent electrode 35, and an opening 61f exposing the first p reflective electrode 25.

[0228] Interconnection lines 71 and 75 may be formed on the support substrate 51 near the first LED stack 23, the second LED stack 33, and the third LED stack 43, and may be disposed on the first insulating layer 61 to be insulated from the first p-reflective electrode 25. Furthermore, a connector 77 a connects the third p-transparent electrode 45 to the first p-reflective electrode 25, a connector 77 b connects the second p-transparent electrode 35 to the first p-reflective electrode 25, and the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 are commonly connected to the first p-reflective electrode 25.

[0229] In addition, the connection member 71 a connects the upper surface of the third LED stack 43 to the interconnection line 71 , and the connection member 75 a connects the upper surface of the first LED stack 23 to the interconnection line 75 .

[0230] The second insulating layer 81 is disposed on the interconnection lines 71 and 75 and the first insulating layer 61 and may cover the upper surface of the third LED stack 43. The second insulating layer 81 may have an opening 81a exposing a portion of the upper surface of the second LED stack 33.

[0231] The interconnection line 73 may be disposed on the second insulating layer 81, and the connector 73a may connect the upper surface of the second LED stack 33 to the interconnection line 73. The connector 73a may pass over the upper portion of the interconnection line 75 and be insulated from the interconnection line 75 by the second insulating layer 81.

[0232] As described above, the electrode of each pixel according to the exemplary embodiment may be connected to the data line and the scan line. Specifically, Figures 4 to 7 Interconnections 71 and 75 are shown formed on first insulating layer 61, and interconnection 73 is formed on second insulating layer 81. However, the inventive concept is not limited thereto. For example, each of interconnections 71, 73, and 75 may be formed on first insulating layer 61 and covered by second insulating layer 81, and second insulating layer 81 may have an opening exposing interconnection 73. In this case, connector 73a may connect the upper surface of second LED stack 33 to interconnection 73 through the opening of second insulating layer 81.

[0233] In addition, interconnections 71, 73 and 75 can be formed in the supporting substrate 51, and connectors 71a, 73a and 75a can connect the upper surfaces of the first LED stack 23, the second LED stack 33 and the third LED stack 43 to the interconnections 71, 73 and 75 on the first insulating layer 61.

[0234] Figures 8A to 8K is a schematic plan view illustrating a method of manufacturing a display device according to an exemplary embodiment.

[0235] First, provide Figure 1 The light emitting diode stack 100 is shown in FIG.

[0236] Next, refer to Figure 8A , a rough surface 43a may be formed on the upper surface of the third LED stack 43. The rough surface 43a may be formed corresponding to each pixel region on the upper surface of the third LED stack 43. The rough surface 43a may be formed by a chemical etching technique (e.g., by a photo-enhanced chemical etching (PEC) technique).

[0237] Considering the area of ​​the third LED stack 43 to be further etched, the rough surface 43 a may be partially formed within each pixel area, but the inventive concept is not limited thereto and the rough surface 43 a may be formed over the entire upper surface of the third LED stack 43 .

[0238] Reference Figure 8B , and then the peripheral area of ​​the third LED stack 43 is etched in each pixel area to expose the third p transparent electrode 45. The remaining third LED stack 43 may have a rectangular shape or a square shape, and a plurality of recessed portions may be formed along its edge.

[0239] Reference Figure 8C Then, except for a portion of the third p transparent electrode 45 corresponding to one recessed portion formed in the third LED stack 43, the exposed third p transparent electrode 45 is removed to expose the upper surface of the second LED stack 33. Except for the remaining recessed portion of the third p transparent electrode 45, the upper surface of the second LED stack 33 is exposed around the third LED stack 43 and in the other recessed portions of the third LED stack 43.

[0240] Reference Figure 8D , except for a portion of the second LED stack 33 corresponding to another recessed portion of the third LED stack 43 , the exposed second LED stack 33 is removed, thereby exposing the second p transparent electrode 35 .

[0241] Reference Figure 8E Then, the exposed second p transparent electrode 35 is removed except for a portion of the second p transparent electrode 35 corresponding to another recessed portion formed in the third LED stack 43 to expose the first LED stack 23. Therefore, the upper surface of the first LED stack 23 is exposed around the third LED stack 43, and the upper surface of the first LED stack 23 is also exposed to at least one recessed portion of the third LED stack 43.

[0242] Reference Figure 8F The exposed first LED stack 23 is removed except for a portion of the first LED stack 23 corresponding to another recessed portion of the third LED stack 43 to expose the first p reflective electrode 25. The first p reflective electrode 25 is exposed around the third LED stack 43.

[0243] Reference Figure 8G The first p reflective electrode 25 is patterned to form a linear interconnection line, thereby exposing the supporting substrate 51. The first p reflective electrode 25 may be as follows Figure 4 Pixels arranged in a column are connected to each other as shown in .

[0244] Reference Figure 8H , forming a first insulating layer ( Figure 6 and Figure 7 61 in the figure) to cover the pixels. Specifically, the first insulating layer 61 covers the side surfaces of the first LED stack 23, the second LED stack 33, and the third LED stack 43, while covering the first p-reflective electrode 25. In addition, the first insulating layer 61 can at least partially cover the upper surface of the third LED stack 43. When the first insulating layer 61 is a transparent layer such as SiO2, the first insulating layer 61 can cover the entire upper surface of the third LED stack 43. Optionally, when the first insulating layer 61 includes a distributed Bragg reflector, the first insulating layer 61 can expose at least a portion of the upper surface of the third LED stack 43, so that light is emitted to the outside.

[0245] In addition, the first insulating layer 61 may include an opening 61a exposing the third LED stack 43, an opening 61b exposing the second LED stack 33, an opening 61c exposing the first LED stack 23, an opening 61d exposing the third p transparent electrode 45, an opening 61e exposing the second p transparent electrode 35, and an opening 61f exposing the first p reflective electrode 25. At least two openings 61f exposing the first p reflective electrode 25 may be formed.

[0246] Reference Figure 8I Then, interconnects 71 and 75 and connectors 71a, 75a, 77a, and 77b are formed using a lift-off technique or the like. Interconnects 71 and 75 are insulated from the first p-reflective electrode 25 by the first insulating layer 61. Connector 71a electrically connects the third LED stack 43 to interconnect 71, and connector 75a electrically connects the first LED stack 23 to interconnect 75. Furthermore, connector 77a electrically connects the third p-transparent electrode 45 to the first p-reflective electrode 25, and connector 77b electrically connects the second p-transparent electrode 35 to the first p-reflective electrode 25.

[0247] Reference Figure 8J , and then make the second insulating layer ( Figure 6 and Figure 7 The second insulating layer 81 covers the interconnect lines 71 and 75 and the connectors 71a, 75a, 77a, and 77b. The second insulating layer 81 can also cover the entire upper surface of the third LED stack 43. In addition, the second insulating layer 81 has an opening 81a that exposes the upper surface of the second LED stack 33. The second insulating layer 81 can be formed of, for example, a silicon oxide film or a silicon nitride film, and can also include a distributed Bragg reflector. When the second insulating layer 81 includes a distributed Bragg reflector, the second insulating layer 81 can at least partially expose the upper surface of the third LED stack 43 to allow light to be emitted to the outside.

[0248] Reference Figure 8K , then, by using a lift-off technique or the like, interconnection line 73 and connector 73a are formed. Interconnection line 73 is disposed on the second insulating layer 81 and is insulated from the first p-type reflective electrode 25 and interconnections 71 and 75. Connector 73a electrically connects the second LED stack 33 to interconnection line 73. Connector 73a may extend over the upper portion of interconnection line 75 and be insulated from interconnection line 75 by the second insulating layer 81.

[0249] In this way, it is possible to form Figure 5 In addition, as shown in the pixel area Figure 4 As shown in FIG, a plurality of pixels may be formed on a supporting substrate 51 and connected to each other through a first p reflective electrode 25 and interconnection lines 71, 73 and 75, thereby being driven in a passive matrix manner.

[0250] As described above, the manufacturing method of the display device driven in a passive matrix manner has been described according to the exemplary embodiment. However, the inventive concept is not limited to the above-mentioned specific manufacturing method, and can be also used by using Figure 1 The LED stack shown in FIG. 3 can be used to manufacture a display device driven in a passive matrix manner in various ways. For example, interconnection line 73 has been described as being formed on second insulating layer 81, but interconnection line 73 can be formed on first insulating layer 61 together with interconnections 71 and 75, and connector 73a can be formed on first insulating layer 61 to connect second LED stack 33 to interconnection line 73. In addition, interconnections 71, 73, and 75 can be provided in support substrate 51.

[0251] Figure 9 is a schematic circuit diagram of a display device according to another exemplary embodiment. Figure 3 The display device described up to FIG. 8 is configured to be driven in a passive matrix manner, but the display device according to the illustrated embodiment is driven in an active matrix manner.

[0252] Reference Figure 9 According to an exemplary embodiment, the driving circuit includes two or more transistors Tr1 and Tr2 and a capacitor. When the power supply is connected to the selection lines Vrow1 to Vrow3 and the data voltage is applied to the data lines Vdata1 to Vdata3, a voltage is applied to the corresponding light-emitting diode. In addition, a charge is charged in the corresponding capacitor according to the value of Vdata1 to Vdata3. The transistor Tr2 can remain in the on state due to the charged voltage of the capacitor. Therefore, even when the power supply is cut off for the selection line Vrow1, the voltage of the capacitor can be maintained and the voltage can be applied to the light-emitting diodes LED1 to LED3. In addition, the current flowing through LED1 to LED3 can be changed according to the value of Vdata1 to Vdata3. Since the current can always be supplied by Vdd, continuous light emission can be achieved.

[0253] The transistors Tr1 and Tr2 and the capacitor may be formed in the supporting substrate 51. For example, a thin film transistor formed on a silicon substrate may be used for active matrix driving.

[0254] The light emitting diodes LED1, LED2, and LED3 may correspond to the first LED stack 23, the second LED stack 33, and the third LED stack 43 stacked in one pixel. Anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 may be connected to the transistor Tr2, and cathodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43 may be grounded.

[0255] Although Figure 9 A driving circuit for an active matrix driven display device is shown, but the inventive concept is not limited thereto, and other circuits may 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 grounded, alternatively, the anodes of the light emitting diodes may be connected to the current source Vdd, and their cathodes may be connected to different transistors.

[0256] Figure 10 is a schematic plan view of a pixel of a display device according to still another exemplary embodiment. Hereinafter, one pixel among a plurality of pixels arranged on a supporting substrate 151 will be described.

[0257] Reference Figure 10 , except that the supporting substrate 151 is a thin film transistor panel including transistors and capacitors and the first p reflective electrode 25 is defined in the lower region of the first LED stack 23, the pixel according to the exemplary embodiment is substantially similar to the reference 100 . Figures 4 to 7 Described pixels.

[0258] The cathode of the third LED stack 43 is connected to the support base 151 through the connection member 171a. Figure 9 As shown in FIG, the cathode of the third LED stack 43 (e.g., LED3) can be electrically connected to the support base 151 and grounded. The cathodes of the second LED stack 33 (e.g., LED2) and the first LED stack 23 (e.g., LED1) can also be connected to the support base 151 and grounded through connectors 173a and 175a, respectively.

[0259] In addition, the first p reflective electrode 25 is connected to the transistor ( Figure 9 The third p-type transparent electrode 45 and the second p-type transparent electrode 35 are also connected to the transistor ( Tr2 ) provided in the supporting substrate 151 through the connecting members 177 a and 173 b , respectively. Figure 9 Tr2 in ).

[0260] By connecting the first LED stack 23, the second LED stack 33, and the third LED stack 43 as described above, it is possible to construct Figure 9 The circuit for active matrix driving is shown in FIG.

[0261] Although Figure 10 A pixel of a display device for active matrix driving is illustrated, but the inventive concept is not limited thereto, and various modifications may be made to various circuits for active matrix driving.

[0262] In addition, return to reference Figure 1 The first p-type reflective electrode 25, the second p-type transparent electrode 35, and the third p-type transparent electrode 45 are described as being in ohmic contact with the p-type semiconductor layer of the first LED stack 23, the p-type semiconductor layer of the second LED stack 33, and the p-type semiconductor layer of the third LED stack 43, respectively. However, no separate ohmic contact layer is provided in the n-type semiconductor layer. This is because, when the pixel size is as small as 200 microns or less, current diffusion is less difficult even without forming a separate ohmic contact layer in the n-type semiconductor layer. However, for current diffusion, a transparent electrode layer can still be provided on the n-type semiconductor layer of each LED stack if desired.

[0263] The first LED stack 23 , the second LED stack 33 , and the third LED stack 43 may be combined with each other through various configurations.

[0264] Figure 11 is a schematic cross-sectional view of a light emitting diode stack for a display according to yet another exemplary embodiment.

[0265] Reference Figure 11 , similar to Figure 1The light-emitting diode stack 100 may include a supporting substrate 51, a first LED stack 23, a second LED stack 33, a third LED stack 43, a second p transparent electrode 35, a third p transparent electrode 45, a first color filter 137, a second color filter 47, a first bonding layer 153, a second bonding layer 155, and a third bonding layer 157. The light-emitting diode stack 101 may also include a first n reflective electrode 129, a first p transparent electrode 125, and a second n transparent electrode 139.

[0266] The support substrate 51 supports the LED stacks 23, 33, and 43. The support substrate 51 may have a circuit on its surface or in its interior, but the inventive concept is not limited thereto. The support substrate 51 may include, for example, a Si substrate or a Ge substrate.

[0267] The first LED stack 23, the second LED stack 33, and the third LED stack 43 are similar to the reference Figure 1 The first LED stack 23, the second LED stack 33, and the third LED stack 43 are similar, and therefore, detailed descriptions thereof will be omitted to avoid redundancy. Figure 1 The difference between the LED stack 100 and the first LED stack 23 is that the lower surface of the second LED stack 33 is n-type, while their upper surfaces are p-type. The lower surface of the third LED stack 43 is p-type, while the upper surface of the third LED stack 43 is n-type, which is different from the above. Figure 1 The third LED stack 43 is substantially the same.

[0268] Since the upper surface of the first LED stack 23 is p-type, the first p transparent electrode 125 makes ohmic contact with the upper surface of the first LED stack 23. The first p transparent electrode 125 transmits light (eg, red light) generated in the first LED stack 23.

[0269] The first n reflective electrode 129 makes ohmic contact with the lower surface of the first LED stack 23. The first n reflective electrode 129 makes ohmic contact with the first LED stack 23 and reflects light generated in the first LED stack 23. The first n reflective electrode 129 can be formed of, for example, Au—Ti, Au—Sn, or the like. Furthermore, the first n reflective electrode 129 can include a diffusion barrier layer.

[0270] The second p-type transparent electrode 35 makes ohmic contact with the p-type semiconductor layer of the second LED stack 33. Since the upper surface of the second LED stack 33 is p-type, the second p-type transparent electrode 35 is provided on the second LED stack 33. The second p-type transparent electrode 35 may be formed of a metal layer or a conductive oxide layer that is transparent to red and green light.

[0271] The second n-type transparent electrode 139 makes ohmic contact with the lower surface of the second LED stack 33. The second n-type transparent electrode 139 can also be formed of a metal layer or a conductive oxide layer that is transparent to red and green light. The second n-type transparent electrode 139 is partially exposed by patterning the second LED stack 33 to provide a connection terminal for electrically connecting to the n-type semiconductor layer of the second LED stack 33.

[0272] The third p transparent electrode 45 makes ohmic contact with the p-type semiconductor layer of the third LED stack 43. The third p transparent electrode 45 may be formed of a metal layer or a conductive oxide layer that is transparent to red, green, and blue light.

[0273] A first color filter 137 is provided between the first LED stack 23 and the second LED stack 33. Furthermore, a second color filter 47 is provided between the second LED stack 33 and the third LED stack 43. The first color filter 137 transmits light generated in the first LED stack 23 and reflects light generated in the second LED stack 33. The second color filter 47 transmits light generated in the first LED stack 23 and the second LED stack 33 and reflects light generated in the third LED stack 43. Therefore, light generated in the first LED stack 23 can pass through the second LED stack 33 and the third LED stack 43 to be emitted to the outside, and light generated in the second LED stack 33 can pass through the third LED stack 43 to be emitted to the outside. Furthermore, light generated in the second LED stack 33 can be prevented from being incident on the first LED stack 23 and being lost, and light generated in the third LED stack 43 can be prevented from being incident on the second LED stack 33 and being lost.

[0274] According to some exemplary embodiments, the first color filter 137 may reflect light generated in the third LED stack 43 .

[0275] Each of the first color filter 137 and the second color filter 47 can be, for example, a low-pass filter that only passes a low-frequency region (i.e., a long-wave region), a band-pass filter that only passes a predetermined wavelength band, or a band-stop filter that only blocks a predetermined wavelength band. Specifically, the first color filter 137 and the second color filter 47 can be a band-stop filter including a distributed Bragg reflector (DBR). A distributed Bragg reflector can be formed by alternately stacking insulating layers with different refractive indices, for example, by alternately stacking TiO2 and SiO2. In addition, the stop band of the distributed Bragg reflector can be controlled by adjusting the thickness of TiO2 and SiO2. A low-pass filter and a band-pass filter can also be formed by alternately stacking insulating layers with different refractive indices.

[0276] The first bonding layer 153 bonds the first LED stack 23 to the support substrate 51. Figure 11 As shown in FIG, the first n-reflective electrode 129 may be in contact with the first bonding layer 153. The first bonding layer 153 may be light-transmissive or light-impermeable. The first bonding layer 153 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film.

[0277] The second bonding layer 155 bonds the second LED stack 33 to the first LED stack 23. Figure 11 As shown in FIG, the second bonding layer 155 may be provided on the first color filter 137 and may be in contact with the second n transparent electrode 139. The second bonding layer 155 transmits light generated in the first LED stack 23. The second bonding layer 155 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film, and may be formed of, for example, light-transmitting spin-on glass.

[0278] The third bonding layer 157 bonds the third LED stack 43 to the second LED stack 33. Figure 11 , the third bonding layer 157 may be in contact with the second p transparent electrode 35 and in contact with the second color filter 47. The third bonding layer 157 transmits light generated in the first LED stack 23 and the second LED stack 33. The third bonding layer 157 may be, for example, a transparent inorganic insulating film, a transparent organic insulating film, or a transparent conductive film, and may be formed of, for example, light-transmitting spin-on glass.

[0279] 12A to 12F is a schematic cross-sectional view illustrating a method of manufacturing a light emitting diode stack for a display according to still another exemplary embodiment.

[0280] Reference Figure 12A A third LED stack 43 is grown on a third substrate 41, and a third p-type transparent electrode 45 and a second color filter 47 are formed on the third LED stack 43. The third LED stack 43 can be formed of a gallium nitride-based semiconductor layer and can include a GaInN well layer. The third substrate 41 is a substrate on which a gallium nitride-based semiconductor layer can be grown, such as a sapphire substrate. The composition ratio of GaInN can be determined so that the third LED stack 43 emits blue light. The third p-type transparent electrode 45 is in ohmic contact with the p-type semiconductor layer of the third LED stack 43.

[0281] Reference Figure 12BA second LED stack 33 is grown on the second substrate 31, and a second p-type transparent electrode 35 is formed on the second LED stack 33. The second LED stack 33 can be formed of a gallium nitride-based semiconductor layer and can include a GaInN well layer. The second substrate 31 is a substrate on which a gallium nitride-based semiconductor layer can be grown and can be the same as the third substrate 41. The composition ratio of GaInN can be determined so that the second LED stack 33 emits green light. The second p-type transparent electrode 35 is in ohmic contact with the p-type semiconductor layer of the second LED stack 33.

[0282] A third bonding layer 157 is provided on the second color filter 47, and the second substrate 31 is disposed so that the second p transparent electrode 35 is in contact with the third bonding layer 157. The third bonding layer 157 can be formed of, for example, spin-on glass. In this manner, the second LED stack 33 is bonded to the third LED stack 43.

[0283] Reference Figure 12C , and then the second substrate 31 is separated from the second LED stack 33. The second substrate 31 and the second LED stack 33 can be separated using techniques such as laser lift-off or chemical lift-off. When the second substrate 31 is separated, the second LED stack 33 is exposed. Then, a second n transparent electrode 139 is formed on the exposed second LED stack 33. The second n transparent electrode 139 can be formed of a metal layer or a conductive oxide layer. Depending on the exemplary embodiment, the second n transparent electrode 139 can be omitted.

[0284] Reference Figure 12D , a first LED stack 23 is grown on the first substrate 21 , a first p transparent electrode 125 is formed on the first LED stack 23 , and a first color filter 137 is formed on the first p transparent electrode 125 .

[0285] The first substrate 21 may be, for example, a GaAs substrate. Furthermore, 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. The first p-type transparent electrode 125 makes ohmic contact with the p-type semiconductor layer of the first LED stack 23.

[0286] The first color filter 137 and the reference Figure 1 The described first color filter 37 is substantially the same, and thus, a detailed description thereof will be omitted to avoid redundancy.

[0287] A second bonding layer 155 is provided on the second n transparent electrode 139, and the first substrate 21 is disposed so that the first color filter 137 is in contact with the second bonding layer 155. The second bonding layer 155 can be formed of, for example, spin-on glass. Thus, the first LED stack 23 is bonded to the second LED stack 33.

[0288] Reference Figure 12E After the first LED stack 23 is bonded on the second LED stack 33 , the first substrate 21 is removed from the first LED stack 23 by using a chemical etching technique. Thus, the first LED stack 23 is exposed.

[0289] Reference Figure 12F , a first n reflective electrode 129 is formed on the exposed first LED stack 23. The first n reflective electrode 129 includes a metal layer that reflects light generated in the first LED stack 23. Then, a first bonding layer 153 is provided on the first n reflective electrode 129, and the support substrate 51 is bonded to the first bonding layer 153. Then, the third substrate 41 can be separated from the third LED stack 43 by using a technique such as laser lift-off, chemical lift-off, etc. In this way, a structure such as Figure 11 In the light emitting diode stack 101 for a display shown in FIG, the n-type semiconductor layer of the third LED stack 43 in the light emitting diode stack 101 is exposed.

[0290] The display device can be formed by patterning a light-emitting diode stack 101 including a first LED stack 23, a second LED stack 33 and a third LED stack 43 arranged on a supporting substrate 51 in units of pixels, and connecting the first LED stack 23, the second LED stack 33 and the third LED stack 43 through interconnection lines.

[0291] According to exemplary embodiments, multiple pixels can be formed at the wafer level using the LED stack 100 or 101 for a display, which can avoid the process of individually mounting LEDs. Furthermore, because the first LED stack 23, the second LED stack 33, and the third LED stack 43 have a vertically stacked structure, the area of ​​the sub-pixels can be ensured within a limited pixel area. Furthermore, because the light generated by the first LED stack 23 is transmitted through the second LED stack 33 and the third LED stack 43 and emitted to the outside, light loss can be reduced.

[0292] Figure 13 is a schematic plan view of a display device according to an exemplary embodiment, Figure 14 is a schematic cross-sectional view of a light emitting diode pixel for a display according to an exemplary embodiment.

[0293] Reference Figure 13 , the display device 200 includes a supporting substrate 251 and a plurality of pixels 20 arranged on the supporting substrate 251. Each pixel 20 includes a first sub-pixel R, a second sub-pixel G, and a third sub-pixel B.

[0294] Reference Figure 14The support substrate 251 supports the LED stacks 223, 233, and 243. The support substrate 251 may have a circuit on its surface or inside, but the inventive concept is not limited thereto. The support substrate 251 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

[0295] The first subpixel R includes a first LED stack 223, the second subpixel G includes a second LED stack 233, and the third subpixel B includes a third LED stack 243. The first subpixel R is configured to emit light using the first LED stack 223, the second subpixel G is configured to emit light using the second LED stack 233, and the third subpixel B is configured to emit light using the third LED stack 243. The first LED stack 223, the second LED stack 233, and the third LED stack 243 can be driven independently of each other.

[0296] The first LED stack 223, the second LED stack 233, and the third LED stack 243 are stacked vertically and overlap each other. Specifically, the second LED stack 233 is disposed on a portion of the first LED stack 223. The second LED stack 233 may be formed toward (or, referred to as, close to) one side of the first LED stack 223. In addition, the third LED stack 243 is disposed on a portion of the second LED stack 233 and may be formed toward one side of the second LED stack 233. Figure 14 The third LED stack 243 is shown disposed adjacent to the right side of the second LED stack 233 , but the inventive concept is not limited thereto and may be disposed adjacent toward the left side of the second LED stack 233 .

[0297] A portion of the light R generated in the first LED stack 223 may be emitted in an area not covered by the second LED stack 233, another portion of the light R may be emitted through the second LED stack 233, and the remaining portion may be emitted through each of the second LED stack 233 and the third LED stack 243. A portion of the light G generated in the second LED stack 233 may be emitted in an area not covered by the third LED stack 243, and the remaining portion may be emitted through the third LED stack 243. The light B generated in the third LED stack 243 may be emitted through the top surface of the third LED stack 243.

[0298] Generally, in the first LED stack 223, the area covered by the second LED stack 233 may experience light loss, and therefore, light with a higher intensity per unit area may be emitted in the area not covered by the second LED stack 233. In this manner, the area of ​​the area covered by the second LED stack 233 and the area of ​​the area not covered by the second LED stack 233 in the first LED stack 223 can be adjusted to control the intensity of light emitted from the first LED stack 223. Similarly, the area of ​​the area covered by the third LED stack 243 and the area not covered by the third LED stack 243 in the second LED stack 233 can be adjusted to control the intensity of light emitted from the second LED stack 233.

[0299] For example, when the first LED stack 223 emits red light, the second LED stack 233 emits green light, and the third LED stack 243 emits blue light, it may be necessary to reduce the intensity of green light because green light has high visibility. In this case, the area of ​​the second LED stack 233 not covered by the third LED stack 243 can be smaller than the area of ​​the third LED stack 243. Furthermore, since red light has low visibility, it may be necessary to increase the intensity of red light. In this case, the area of ​​the first LED stack 223 not covered by the second LED stack 233 can be larger than the area of ​​the third LED stack 243.

[0300] The first LED stack 223, the second LED stack 233, and the third LED stack 243 each include an n-type semiconductor layer, a p-type semiconductor layer, and an active layer disposed between the n-type semiconductor layer and the p-type semiconductor layer. The active layer may have a multi-quantum well structure. The first LED stack 223, the second LED stack 233, and the third LED stack 243 may include different active layers and thus may emit light of different wavelengths. For example, the first LED stack 223 may be an inorganic light-emitting diode that emits red light, the second LED stack 233 may be an inorganic light-emitting diode that emits green light, and the third LED stack 243 may be an inorganic light-emitting diode that emits blue light. To this end, the first LED stack 223 may include a GaInP base well layer, and the second LED stack 233 and the third LED stack 243 may include a GaInN base well layer.

[0301] Figure 15 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0302] Reference Figure 15 , the display device according to the exemplary embodiment can be implemented to be driven in a passive matrix manner. Figure 13 and Figure 14As depicted, one pixel includes a first subpixel R, a second subpixel G, and a third subpixel B. The first LED stack 223 of the first subpixel R emits light of a first wavelength, the second LED stack 233 of the second subpixel G emits light of a second wavelength, and the third LED stack 243 of the third subpixel B emits light of a third wavelength. The cathodes of the first subpixel R, the second subpixel G, and the third subpixel B can be connected to a common line (e.g., data line Vdata 225), while their anodes can be connected to different lines (e.g., scan lines Vscan 271, 273, and 275).

[0303] More specifically, the cathodes of the first subpixel R, the second subpixel G, and the third subpixel B of the first pixel are commonly connected to the data line Vdata1, while their anodes are connected to the scan lines Vscan1-1, Vscan1-2, and Vscan1-3. Therefore, the subpixels R, G, and B in the same pixel can be driven independently.

[0304] Furthermore, each of the LED stacks 223, 233, and 243 can be driven in a pulse width modulation scheme or by varying the current intensity, thereby adjusting the brightness of each sub-pixel. Figure 14 As shown in , brightness can be adjusted by adjusting the areas of the first LED stack 223 , the second LED stack 233 , and the third LED stack 243 and the areas of regions where the LED stacks 223 , 233 , and 243 do not overlap.

[0305] Figure 16 is a schematic plan view of a display device according to an exemplary embodiment. The display device 200A includes a display device according to Figure 15 A circuit diagram of a plurality of pixels 20A aligned on a supporting substrate 251. Figure 17 yes Figure 16 FIG. 1 is an enlarged plan view of one pixel 20A of a display device. 18A to 18D Along Figure 17 Schematic cross-sectional views taken along lines AA, BB, CC and DD.

[0306] Reference Figure 16 、 Figure 17 、 Figure 18A 、 Figure 18B 、 Figure 18C and Figure 18DThe display device 200A may include a supporting substrate 251 and a plurality of pixels 20A disposed on the supporting substrate 251. Each pixel 20A includes a first subpixel R, a second subpixel G, and a third subpixel B. More specifically, the pixel 20A includes a first LED stack 223, a second LED stack 233, a third LED stack 243, a reflective electrode 225, a first ohmic electrode 229, a second transparent electrode 236, a second ohmic electrode 237, a second current spreading layer 239, a third transparent electrode 246, a third ohmic electrode 247, a third current spreading layer 249, a first color filter 235, a second color filter 245, a first bonding layer 253, a second bonding layer 255, a third bonding layer 257, an insulating layer 227, a lower insulating layer 261, an upper insulating layer 263, interconnection lines 271, 273, and 275, and connectors 271a, 273a, 275a, 277a, and 277b.

[0307] Each sub-pixel R, G, and B is connected to the reflective electrode 225 and the interconnection lines 271, 273, and 275. Figure 15 As shown in FIG, the reflective electrode 225 may be used as a data line Vdata, and the interconnection lines 271, 273, and 275 may be used as a scan line Vscan.

[0308] like Figure 16 As shown in FIG, the pixels 20A may be arranged in a matrix, with the cathodes of the sub-pixels R, G, and B of each pixel 20A commonly connected to the reflective electrode 225, and their anodes respectively connected to interconnection lines 271, 273, and 275 spaced apart from each other. Connectors 271a, 273a, and 275a may connect the interconnection lines 271, 273, and 275 to the sub-pixels R, G, and B, respectively.

[0309] The support substrate 251 supports the LED stacks 223, 233, and 243. The support substrate 251 may have a circuit on its surface or in its interior, but the inventive concept is not limited thereto. The support substrate 251 may include, for example, a glass substrate, a sapphire substrate, a Si substrate, or a Ge substrate.

[0310] The first LED stack 223 includes a first conductive type semiconductor layer 223a and a second conductive type semiconductor layer 223b, the second LED stack 233 includes a first conductive type semiconductor layer 233a and a second conductive type semiconductor layer 233b, and the third LED stack 243 includes a first conductive type semiconductor layer 243a and a second conductive type semiconductor layer 243b. Furthermore, although not shown, active layers may be interposed between the first conductive type semiconductor layer 223a and the second conductive type semiconductor layer 223b, between the first conductive type semiconductor layer 233a and the second conductive type semiconductor layer 233b, and between the first conductive type semiconductor layer 243a and the second conductive type semiconductor layer 243b, respectively.

[0311] According to an exemplary embodiment, the first conductive type semiconductor layers 223a, 233a, and 243a are all n-type semiconductor layers, and the second conductive type semiconductor layers 223b, 233b, and 243b are all p-type semiconductor layers. A rough surface may be formed on at least one surface of the first conductive type semiconductor layers 223a, 233a, and 243a by surface texturing.

[0312] The first LED stack 223 is positioned closer to the support base 251, the second LED stack 233 is positioned on the first LED stack 223, and the third LED stack 243 is positioned on the second LED stack 233. Furthermore, the second LED stack 233 is positioned on a portion of the first LED stack 223, so that the first LED stack 223 and the second LED stack 233 partially overlap. Furthermore, the third LED stack 243 is positioned on a portion of the second LED stack 233, so that the second LED stack 233 and the third LED stack 243 partially overlap. In this manner, at least a portion of the light generated in the first LED stack 223 can be emitted to the outside without passing through the second LED stack 233 and the third LED stack 243. Furthermore, at least a portion of the light generated in the second LED stack 233 can be emitted to the outside without passing through the third LED stack 243.

[0313] The first LED stack 223 , the second LED stack 233 , and the third LED stack 243 may include Figure 14 The materials of the LED stacks 223 , 233 , and 243 are substantially the same material, and thus, a detailed description thereof will be omitted to avoid redundancy.

[0314] The reflective electrode 225 makes ohmic contact with the lower surface of the first LED stack 223 (more specifically, the first conductive semiconductor layer 223a). The reflective electrode 225 includes a reflective layer to reflect light emitted from the first LED stack 223. The reflective electrode 225 may substantially overlap the entire lower surface of the first LED stack 223. Furthermore, the reflective electrode 225 may be commonly connected to a plurality of pixels 20A and serve as a data line Vdata.

[0315] The reflective electrode 225 may be formed of a material layer forming an ohmic contact with the first conductive type semiconductor layer 223 a of the first LED stack 223 , and may further include a reflective layer reflecting light (eg, red light) generated in the first LED stack 223 .

[0316] The reflective electrode 225 may include an ohmic reflective layer and may be formed of, for example, Au-Te alloy, Au-Ge alloy, etc. These alloys have high reflectivity to light in the red region and form an ohmic contact with the first conductive type semiconductor layer 223a.

[0317] The first ohmic electrode 229 is in ohmic contact with the second conductive semiconductor layer 223b of the first sub-pixel R. The first ohmic electrode 229 can be formed of, for example, an Au-Zn alloy, an Au-Be alloy, etc. The first ohmic electrode 229 can include a pad region and an extension portion. Figure 18B As shown in FIG, the connection member 275a may be connected to a pad region of the first ohmic electrode 229. The first ohmic electrode 229 may be spaced apart from the second LED stack 233.

[0318] The second ohmic electrode 237 makes ohmic contact with the first conductive semiconductor layer 233a of the second LED stack 233. The second ohmic electrode 237 may be disposed on the first conductive semiconductor layer 233a. For example, the second conductive semiconductor layer 233b and the active layer disposed on the first conductive semiconductor layer 233a may be partially removed to expose the first conductive semiconductor layer 233a, and the second ohmic electrode 237 may be disposed on the exposed first conductive semiconductor layer 233a.

[0319] like Figure 18C As shown in FIG, the connector 277b may electrically connect the second ohmic electrode 237 to the reflective electrode 225. The second ohmic electrode 237 may be spaced apart from the third LED stack 243.

[0320] The second transparent electrode 236 makes ohmic contact with the second conductive semiconductor layer 233 b on the upper surface of the second LED stack 233. The second transparent electrode 236 may substantially cover the entire area of ​​the second conductive semiconductor layer 233 b. Thus, the second transparent electrode 236 may surround the third LED stack 243 in a plan view and be positioned between the second and third LED stacks 233 and 243. The second transparent electrode 236 may be formed of a transparent oxide layer or a transparent metal layer.

[0321] The second transparent electrode 236 according to an exemplary embodiment is provided on the upper surface side of the second LED stack 233 that is relatively spaced further away from the support substrate 251. In this manner, the second transparent electrode 236 can be formed on the second LED stack 233 after the growth substrate of the second LED stack 233 is removed. In this manner, the second transparent electrode 236 is prevented from being damaged during the removal of the growth substrate.

[0322] The second current spreading layer 239 may be disposed on the second transparent electrode 236 and may be electrically connected to the second conductive type semiconductor layer 233b through the second transparent electrode 236. The second current spreading layer 239 may be spaced apart from the third LED stack 243. The second current spreading layer 239 may be as shown in FIG. Figure 17 , the second current spreading layer 239 includes a pad region and an extension portion, and the connection member 273 a may be connected to the pad region of the second current spreading layer 239 .

[0323] The second ohmic electrode 237 and the second current spreading layer 239 may be formed together using the same material layer during the same process. Therefore, the second ohmic electrode 237 and the second current spreading layer 239 may have substantially the same layer structure.

[0324] The third ohmic electrode 247 is in ohmic contact with the first conductive semiconductor layer 243a of the third LED stack 243. The third ohmic electrode 247 may be disposed on the first conductive semiconductor layer 243a. For example, the second conductive semiconductor layer 243b and the active layer disposed on the first conductive semiconductor layer 243a may be partially removed to expose the first conductive semiconductor layer 243a, and the third ohmic electrode 247 may be disposed on the exposed first conductive semiconductor layer 243a. Figure 18D As shown in FIG, the connector 277 a may electrically connect the third ohmic electrode 247 to the reflective electrode 225 .

[0325] The third transparent electrode 246 may be in ohmic contact with the second conductive semiconductor layer 243b of the third LED stack 243. The third transparent electrode 246 may substantially cover the entire area of ​​the second conductive semiconductor layer 243b. The third transparent electrode 246 may be formed of a transparent oxide layer or a transparent metal layer.

[0326] The third transparent electrode 246 according to an exemplary embodiment is disposed on an upper surface of the third LED stack 243 relatively spaced further away from the support substrate 251. In this manner, the third transparent electrode 246 can be formed on the third LED stack 243 after the growth substrate of the third LED stack 243 is removed, thereby preventing the third transparent electrode 246 from being damaged during the removal of the growth substrate.

[0327] The third current spreading layer 249 may be disposed on the third transparent electrode 246 and may be electrically connected to the second conductive type semiconductor layer 243b through the third transparent electrode 246. The third current spreading layer 249 may include a pad region and an extension portion, and may be electrically connected to the second conductive type semiconductor layer 243b through the third transparent electrode 246. Figure 18D As shown in , the connection member 271 a may be connected to the pad region of the third current spreading layer 249 .

[0328] Each of the first ohmic electrode 229 , the second current spreading layer 239 , and the third current spreading layer 249 may include an extension portion to facilitate current spreading within each LED stack.

[0329] The third ohmic electrode 247 and the third current spreading layer 249 can be formed together using the same material layer during the same process. Therefore, the third ohmic electrode 247 and the third current spreading layer 249 can have substantially the same layer structure. In addition, all of the second ohmic electrode 237, the second current spreading layer 239, the third ohmic electrode 247, and the third current spreading layer 249 can be formed in the same process and have substantially the same structure.

[0330] A first color filter 235 may be provided between the first LED stack 223 and the second LED stack 233. Furthermore, a second color filter 245 may be provided between the second LED stack 233 and the third LED stack 243. The first color filter 235 transmits light generated in the first LED stack 223 and reflects light generated in the second LED stack 233. Furthermore, the second color filter 245 transmits light generated in the first LED stack 223 and the second LED stack 233 and reflects light generated in the third LED stack 243. Therefore, light generated in the first LED stack 223 can be emitted to the outside through the second LED stack 233 and the third LED stack 243, and light generated in the second LED stack 233 can be emitted to the outside through the third LED stack 243. Furthermore, light generated in the second LED stack 233 can be prevented from being incident on the first LED stack 223 and being lost, and light generated in the third LED stack 243 can be prevented from being incident on the second LED stack 233 and being lost.

[0331] According to some exemplary embodiments, the first color filter 235 may reflect light generated in the third LED stack 243 .

[0332] Each of the first color filter 235 and the second color filter 245 can be, for example, a low-pass filter that only passes a low-frequency region (i.e., a long-wave region), a band-pass filter that only passes a predetermined band, or a band-stop filter that only blocks a predetermined band. Specifically, the first color filter 235 and the second color filter 245 can be formed by alternately stacking insulating layers with different refractive indices. For example, the first color filter 235 and the second color filter 245 can be formed by alternately stacking TiO2 and SiO2. Specifically, the first color filter 235 and the second color filter 245 can include a distributed Bragg reflector (DBR). The stop band of 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 alternately stacking insulating layers with different refractive indices.

[0333] The first bonding layer 253 bonds the first LED stack 223 to the supporting substrate 251. The reflective electrode 225 may be in contact with the first bonding layer 253. The first bonding layer 253 may be light-transmissive or opaque. The first bonding layer 253 may be formed of an organic material layer or an inorganic material layer. Examples of the organic material layer may include SU8, poly(methyl methacrylate) (PMMA), polyimide, polyparaxylene, benzocyclobutene (BCB), etc. Examples of the inorganic material layer may include Al2O3, SiO2, SiN x Etc. The organic material layer can be bonded under high vacuum and high pressure. The inorganic material layer can be surface-planarized by, for example, a chemical mechanical polishing process, and then the surface energy of the inorganic material layer can be controlled by using plasma, etc., and the surface energy can be used to bond the inorganic material layer under high vacuum. Specifically, when a light-absorbing adhesive layer (such as black epoxy resin) is used in the first bonding layer 253, the contrast of the display device can be improved. The first bonding layer 253 can also be formed of spin-on glass.

[0334] The second bonding layer 255 bonds the first LED stack 223 to the second LED stack 233. The second bonding layer 255 may be disposed between the first LED stack 223 and the first color filter 235. The second bonding layer 255 may transmit light generated in the first LED stack 223 and may be formed of the light-transmitting bonding material described above with reference to the first bonding layer 253.

[0335] The insulating layer 227 may be interposed between the second bonding layer 255 and the first LED stack 223. The insulating layer 227 may be in contact with the second conductive type semiconductor layer 223b. The insulating layer 227 may be formed of, for example, SiO2, thereby improving the bonding strength of the second bonding layer 255.

[0336] The third bonding layer 257 bonds the second LED stack 233 and the third LED stack 243. The third bonding layer 257 may be provided between the second LED stack 233 and the second color filter 245 to bond the second LED stack 233 and the second color filter 245. The third bonding layer 257 may transmit light generated in the first LED stack 223 and light generated in the second LED stack 233, and may be formed of the light-transmitting bonding material described above with reference to the first bonding layer 253.

[0337] The lower insulating layer 261 may cover the first LED stack 223, the second LED stack 233, and the third LED stack 243. Specifically, the lower insulating layer 261 covers the reflective electrode 225 exposed around the first LED stack 223. In addition, the lower insulating layer 261 may have an opening for providing an electrical connection path.

[0338] The upper insulating layer 263 covers the lower insulating layer 261. The upper insulating layer 263 may also have openings for providing electrical connection paths.

[0339] The lower insulating layer 261 and the upper insulating layer 263 are not particularly limited as long as they have insulating properties, and may be formed of, for example, silicon oxide or silicon nitride.

[0340] like Figure 16 and Figure 17 As shown in FIG, interconnection lines 271, 273, and 275 may be arranged in a plan view to be orthogonal to the exposed reflective electrode 225. The interconnection lines 271 and 275 may be provided on the upper insulating layer 263 and may be connected to the third current spreading layer 249 and the first ohmic electrode 229 through connectors 271a and 275a, respectively. To this end, the upper insulating layer 263 and the lower insulating layer 261 may have openings that expose the third ohmic electrode 247 and the first ohmic electrode 229.

[0341] The interconnection line 273 is disposed on the lower insulating layer 261 and is insulated from the reflective electrode 225. The interconnection line 273 may be disposed between the lower insulating layer 261 and the upper insulating layer 263 and may be connected to the second current spreading layer 239 through a connector 273a. To this end, the lower insulating layer 261 has an opening that exposes the second current spreading layer 239.

[0342] Connectors 277a and 277b are disposed between the lower insulating layer 261 and the upper insulating layer 263. Thus, the third ohmic electrode 247 and the second ohmic electrode 237 are electrically connected to the reflective electrode 225. To this end, the lower insulating layer 261 may have openings exposing the third ohmic electrode 247 and the second ohmic electrode 237.

[0343] The interconnection lines 271 and 273 may be insulated from each other by the upper insulating layer 263 , and thus, the interconnection lines 271 and 273 may be arranged to overlap each other in a vertical direction.

[0344] Figures 16 to 18D The display device 200A has a structure in which the electrode of each pixel is connected to the data line and the scan line. Specifically, Figure 16 The interconnection lines 271 and 275 are provided on the upper insulating layer 263, and the interconnection line 273 is provided between the lower insulating layer 261 and the upper insulating layer 263. However, the inventive concept is not limited thereto. For example, the interconnection lines 271 and 275 may be formed on the lower insulating layer 261 together with the interconnection line 273 and may be covered by the upper insulating layer 263, and the connectors 271a and 275a may be formed on the upper insulating layer 263.

[0345] Hereinafter, a method of manufacturing the display device 200A according to the above-described exemplary embodiment will be described.

[0346] Figures 19A to 33 1 is a schematic plan view and a cross-sectional view illustrating a method of manufacturing a display device according to an exemplary embodiment. Figures 19A to 33 , each cross-sectional view is taken along line AA of the corresponding plan view.

[0347] Reference Figure 19A and Figure 19B The first LED stack 223 is grown on the first substrate 221. The first substrate 221 may be, for example, a GaAs substrate. The first LED stack 223 is formed of an AlGaInP-based semiconductor layer and includes a first conductive semiconductor layer 223a, an active layer, and a second conductive semiconductor layer 223b.

[0348] An insulating layer 227 is formed on the first LED stack 223. The insulating layer 227 is patterned to have an opening exposing the second conductive type semiconductor layer 223b. The insulating layer 227 may be formed of a hydrophilic material (eg, SiO2) layer. According to an exemplary embodiment, the insulating layer 227 may be omitted.

[0349] A first ohmic electrode 229 may be formed in the opening of the insulating layer 227. The first ohmic electrode 229 may be formed of, for example, an Au-Zn alloy, an Au-Be alloy, or the like. The first ohmic electrode 229 may be formed to have a pad region and an extension portion. The first ohmic electrode 229 may be formed by a lift-off technique and may be formed in each pixel region. Figure 19A As shown in FIG, the first ohmic electrode 229 is disposed toward a side of the pixel region.

[0350] Next, refer to Figure 20A , the initial substrate 321a can be attached to the first LED stack 223 via the bonding layer 323a. The initial substrate 321a is not particularly limited and can be any substrate capable of supporting the first LED stack 223. In addition, the first substrate 221 is removed from the first LED stack 223 using a chemical etching technique to expose the first conductive semiconductor layer 223a of the first LED stack 223. The exposed surface of the first conductive semiconductor layer 223a is roughened by surface texturing.

[0351] A reflective electrode 225 is formed on the exposed first LED stack 223. The reflective electrode 225 can be formed of, for example, an Au-Te alloy, an Au-Ge alloy, or the like. The reflective electrode 225 can be formed using a lift-off technique and can be patterned to have a specific shape. For example, the reflective electrode 225 can be patterned to have a shape that vertically connects multiple pixels. However, the inventive concept is not limited thereto, and the reflective electrode 225 can be formed substantially over the entire surface of the first LED stack 223 without patterning, and then patterned in a subsequent step. The reflective electrode 225 can be in ohmic contact with the first conductive semiconductor layer 223a of the first LED stack 223, which can be an n-type semiconductor layer.

[0352] Reference Figure 20B , the support substrate 251 is bonded to the first LED stack 223 via the first bonding layer 253. The reflective electrode 225 on the first LED stack 223 may be disposed to face the support substrate 251 so as to be bonded to the support substrate 251. Therefore, the first bonding layer 253 may be in contact with the reflective electrode 225 and the first conductive type semiconductor layer 223a.

[0353] After bonding the support substrate 251, the preliminary substrate 321a and the bonding layer 323a may be removed, thereby exposing the insulating layer 227 and the first ohmic electrode 229.

[0354] Reference Figure 21A A second LED stack 233 is grown on a second substrate 231. The second LED stack 233 may be formed of a gallium nitride-based semiconductor layer and may include a first conductivity-type semiconductor layer 233a, a GaInN well layer, and a second conductivity-type semiconductor layer 233b. The second substrate 231 is a substrate on which a gallium nitride-based semiconductor layer may be grown and may be different from the first substrate 221. The composition ratio of GaInN may be determined so that the second LED stack 233 emits green light.

[0355] Reference Figure 21B The initial substrate 321b is attached to the second LED stack 233 via the bonding layer 323b. The initial substrate 321b is not particularly limited, but may be any substrate capable of supporting the second LED stack 233.

[0356] Reference Figure 21C , and then remove the second substrate 231. The second substrate 231 can be separated from the second LED stack 233 by using a technique such as laser lift-off or chemical lift-off to expose the first conductive semiconductor layer 233a of the second LED stack 233. The exposed surface of the first conductive semiconductor layer 233a can be roughened by surface texturing.

[0357] A first color filter 235 may be formed on the exposed first conductive type semiconductor layer 233a. The first color filter 235 may be in contact with the first conductive type semiconductor layer 233a. The material of the first color filter 235 may be the same as that of the first conductive type semiconductor layer 233a. Figure 18A The materials of the first color filters 235 are substantially the same, and a detailed description thereof will be omitted to avoid redundancy.

[0358] Reference Figure 22A A third LED stack 243 is grown on a third substrate 241. The third LED stack 243 may be formed of a gallium nitride-based semiconductor layer and may include a first-conductivity-type semiconductor layer 243a, a GaInN well layer, and a second-conductivity-type semiconductor layer 243b. The third substrate 241 is a substrate on which a gallium nitride-based semiconductor layer may be grown and may be different from the first substrate 221. The composition ratio of GaInN may be determined so that the third LED stack 243 emits blue light.

[0359] Reference Figure 22B The preliminary substrate 321c is attached to the third LED stack 243 via the bonding layer 323c. The preliminary substrate 321c is not particularly limited, but may be any substrate capable of supporting the third LED stack 243.

[0360] Reference Figure 22C , and then remove the third substrate 241. The third substrate 241 can be separated from the third LED stack 243 by using a technique such as laser lift-off or chemical lift-off to expose the first conductive semiconductor layer 243a of the third LED stack 243. The exposed surface of the first conductive semiconductor layer 243a can be roughened by surface texturing.

[0361] A second color filter 245 may be formed on the exposed first conductive type semiconductor layer 243a. The second color filter 245 may be in contact with the first conductive type semiconductor layer 243a. The material of the second color filter 245 may be the same as that of the first conductive type semiconductor layer 243a. Figure 18A The materials of the second color filter 245 are substantially the same, and thus, a detailed description thereof will be omitted to avoid redundancy.

[0362] In addition, since the first LED stack 223 , the second LED stack 233 , and the third LED stack 243 are grown on different substrates, the order in which the LED stacks are formed is not particularly limited.

[0363] Reference Figure 23A and Figure 23B First, Figure 21C The second LED stack 233 is bonded to the Figure 20B The insulating layer 227 and the first ohmic electrode 229 are exposed.

[0364] The first color filter 235 may be disposed to face the support substrate 251 and bonded to the insulating layer 227 through the second bonding layer 255. The second bonding layer 255 may be formed of a light-transmitting material.

[0365] Subsequently, the initial substrate 321b and the bonding layer 323b are removed to expose the second conductive type semiconductor layer 233b, and a second transparent electrode 236 is formed on the exposed second conductive type semiconductor layer 233b. The second transparent electrode 236 is in ohmic contact with the second conductive type semiconductor layer 233b. The second transparent electrode 236 can substantially cover the entire area of ​​the second conductive type semiconductor layer 233b.

[0366] Since the second transparent electrode 236 is formed after the second substrate 231 is removed from the second LED stack 233 , the second transparent electrode 236 may be prevented from being damaged during the process of removing the second substrate 231 .

[0367] Reference Figure 24A and Figure 24B ,Will Figure 22C The third LED stack 243 is bonded to the second LED stack 233 having the second transparent electrode 236 formed thereon via a third bonding layer 257 .

[0368] The second color filter 245 may be disposed to face the second LED stack 233, and bonded to the second transparent electrode 236 through a third bonding layer 257. The third bonding layer 257 may be formed of a light-transmitting material.

[0369] Subsequently, the initial substrate 321c and the bonding layer 323c are removed to expose the second conductive type semiconductor layer 243b, and a third transparent electrode 246 is formed on the exposed second conductive type semiconductor layer 243b. The third transparent electrode 246 is in ohmic contact with the second conductive type semiconductor layer 243b. The third transparent electrode 246 can substantially cover the entire area of ​​the second conductive type semiconductor layer 243b.

[0370] Reference Figure 25A and Figure 25B , patterning the third transparent electrode 246, the second conductive type semiconductor layer 243b and the active layer to expose the first conductive type semiconductor layer 243a in each pixel region. The third transparent electrode 246 may be left while being defined in the third sub-pixel region and may be as Figure 25A The diagram shown includes a recessed portion.

[0371] Then, a third current spreading layer 249 and a third ohmic electrode 247 are formed on the third transparent electrode 246 and the first conductive semiconductor layer 243a, respectively. The third ohmic electrode 247 can be formed in the recessed portion. The third ohmic electrode 247 and the third current spreading layer 249 can be formed from the same material layer during the same process, and thus, the third ohmic electrode 247 and the third current spreading layer 249 can have substantially the same structure. However, the inventive concept is not limited thereto, and the third ohmic electrode 247 and the third current spreading layer 249 can be formed in separate processes. For example, the third current spreading layer 249 can be formed before the third transparent electrode 246 is patterned, and can be formed after the first conductive semiconductor layer 243a is exposed, or vice versa. Furthermore, the third ohmic electrode 247 and the third current spreading layer 249 can be formed together with the second current spreading layer 239, which will be described below.

[0372] Reference Figure 26A and Figure 26B The second transparent electrode 236 is exposed by sequentially patterning the first conductive semiconductor layer 243a, the second color filter 245, and the third bonding layer 257. In this way, the third sub-pixel B is defined, and the second transparent electrode 236 is exposed around the third sub-pixel region B.

[0373] Reference Figure 27A and Figure 27B The second transparent electrode 236, the second conductive type semiconductor layer 233b and the active layer are patterned to expose the first conductive type semiconductor layer 233a. The second transparent electrode 236 can be left while being defined in the second sub-pixel region and can be as Figure 27A The diagram shown includes a recessed portion.

[0374] Then, a second current spreading layer 239 and a second ohmic electrode 237 are formed on the second transparent electrode 236 and the first conductive type semiconductor layer 233a, respectively. The second ohmic electrode 237 may be formed in the recessed portion. The second ohmic electrode 237 and the second current spreading layer 239 may be formed from the same material layer during the same process, and thus, the second ohmic electrode 237 and the second current spreading layer 239 may have substantially the same structure.

[0375] In addition, the third ohmic electrode 247 and the third current spreading layer 249 may also be formed together with the second ohmic electrode 237 and the second current spreading layer 239 during the same process and from the same material layer.

[0376] However, the inventive concept is not limited thereto, and the second ohmic electrode 237 and the second current spreading layer 239 may be formed in different processes. For example, the second current spreading layer 239 may be formed first before the second transparent electrode 236 is patterned, and the second ohmic electrode 237 may be formed after the first conductive type semiconductor layer 233a is exposed, or vice versa.

[0377] Reference Figure 28A and Figure 28B The second conductive semiconductor layer 223b is exposed by sequentially patterning the first conductive semiconductor layer 233a, the first color filter 235, the second bonding layer 255, and the insulating layer 227. In this manner, a second sub-pixel G is defined, and the second conductive semiconductor layer 223b is exposed around the second sub-pixel region G. Furthermore, the first ohmic electrode 229 is exposed on the outer side of the second LED stack 233, and the second LED stack 233 partially overlaps the third LED stack 243. Specifically, the third LED stack 243 is configured to be confined within a region of the second LED stack 233.

[0378] Reference Figure 29A and Figure 29B The first LED stack 223 is patterned to remove the first LED stack 223 from a portion other than the first sub-pixel R region. Furthermore, the first ohmic electrode 229 may remain in the first sub-pixel R region. The first LED stack 223 partially overlaps the second LED stack 233 and the third LED stack 243. Specifically, the second LED stack 233 and the third LED stack 243 are arranged to be confined within a region of the first LED stack 223.

[0379] In addition, by patterning the first LED stack 223, the reflective electrode 225 may be exposed, and the surface of the first bonding layer 253 may also be partially exposed. According to another exemplary embodiment, an insulating layer may be provided on the first bonding layer 253, and thus, the insulating layer may be exposed instead of the first bonding layer 253.

[0380] According to exemplary embodiments, each of the first ohmic electrode 229, the second current spreading layer 239, and the third current spreading layer 249 may include a pad region and an extension portion, and the extension portion may extend along a length direction of the exposed reflective electrode 225. However, the inventive concept is not limited thereto.

[0381] Reference Figure 30A and Figure 30B, and then a lower insulating layer 261 is formed to cover the first LED stack 223, the second LED stack 233, the third LED stack 243, the reflective electrode 225, and the first bonding layer 253. The second transparent electrode 236 and the third transparent electrode 246 are also covered by the lower insulating layer 261. The lower insulating layer 261 can be patterned to form openings that expose the first ohmic electrode 229, the second ohmic electrode 237, the second current spreading layer 239, the third ohmic electrode 247, the third current spreading layer 249, and the reflective electrode 225.

[0382] Reference Figure 31 , an interconnection line 273 and connectors 273a, 277a, and 277b are formed on the lower insulating layer 261. The connector 273a connects the second current spreading layer 239 to the interconnection line 273, the connector 277a connects the third ohmic electrode 247 to the reflective electrode 225, and the connector 277b connects the second ohmic electrode 237 to the reflective electrode 225. Figure 31 The cross-sectional view taken along line AA is Figure 30B same.

[0383] Reference Figure 32A and Figure 32B Then, an upper insulating layer 263 is formed to cover the interconnection line 273 and the connectors 273a, 277a, and 277b. The upper insulating layer 263 may be patterned to expose the pad region of the first ohmic electrode 229 and the pad region of the third current spreading layer 249.

[0384] Reference Figure 33 Then, interconnection lines 271 and 275 and connectors 271a and 275a are formed on the upper insulating layer 263. The connector 271a connects the interconnection line 271 to the third current spreading layer 249, and the connector 275a connects the interconnection line 275 to the first ohmic electrode 229.

[0385] Thus, creating a reference Figure 16 and Figure 17 Display device 200A is described.

[0386] Figure 34 is a schematic cross-sectional view of a display device according to another exemplary embodiment.

[0387] Reference Figure 34 , except that a transparent electrode 226 is provided on an upper surface of the first LED stack 223 and a first current spreading layer 229 is provided on the transparent electrode 226, the display device according to the exemplary embodiment is similar to Figure 16 and Figure 17A display device. Specifically, a transparent electrode 226 is provided on the second conductive semiconductor layer 223b to make ohmic contact therewith. The transparent electrode 226 can substantially cover the entire upper surface of the first LED stack 223 and, therefore, can be positioned between the first LED stack 223 and the second LED stack 233 and outside the second LED stack 233.

[0388] In forming a reference Figure 19A Before forming the insulating layer 227 as described above, a transparent electrode 226 may be formed to cover most of the second conductive type semiconductor layer 223b. In addition, the insulating layer 227 may be omitted. In addition, the first current spreading layer 229 may be formed directly on the transparent electrode 226. Alternatively, as described with reference to FIG. Figure 28A and Figure 28B As described, the first current spreading layer 229 may be formed after the first conductive semiconductor layer 233 a , the first color filter 235 , the second bonding layer 255 , and the insulating layer 227 are patterned to expose the transparent electrode 226 , thereby defining the second sub-pixel region G.

[0389] In this manner, since the first current spreading layer 229 does not need to be in ohmic contact with the second conductive semiconductor layer 223 b by forming the transparent electrode 226, the first current spreading layer 229 can be formed of the same material layer as the second current spreading layer 239 or the third current spreading layer 249. Therefore, when forming the second ohmic electrode 237, the second current spreading layer 239, the third ohmic electrode 247, and the third current spreading layer 249, the first current spreading layer 229 can also be formed of the same material layer during the same process.

[0390] in addition, Figure 34 The display device is described as including pixels driven in a passive matrix driving manner, however, the inventive concept is not limited thereto, and the pixels may be driven in an active matrix driving manner.

[0391] Figure 35 FIG. 1 is a schematic circuit diagram of a display device according to another exemplary embodiment. Here, the circuit diagram of the display device is driven in an active matrix manner.

[0392] Reference Figure 35According to an exemplary embodiment, the driving circuit includes two or more transistors Tr1 and Tr2 and a capacitor. When the power supply is connected to the selection lines Vrow1 to Vrow3 and the data voltage is applied to the data lines Vdata1 to Vdata3, a voltage is applied to the corresponding light-emitting diode. In addition, a charge is charged in the corresponding capacitor according to the value of Vdata1 to Vdata3. The transistor Tr2 can be kept in an on state by the charge voltage of the capacitor. Therefore, even when the power supply is cut off for the selection line Vrow1, the voltage of the capacitor can be maintained and the voltage can be applied to the light-emitting diodes LED1 to LED3. In addition, the current flowing through LED1 to LED3 can be changed according to the value of Vdata1 to Vdata3. Since the current can always be supplied by Vdd, light can be emitted continuously.

[0393] The transistors Tr1 and Tr2 and the capacitors may be formed in the support substrate 251. The support substrate 251 may also have connection pads on its surface to connect the transistors to the capacitors. In addition, the select lines and data lines may be provided in (or on) the support substrate 251, and thus the interconnect lines 271, 273, and 275 described above may be omitted.

[0394] The light-emitting diodes LED1 to LED3 may correspond to the first LED stack 223, the second LED stack 233, and the third LED stack 243, respectively, in one pixel. The anodes of the first LED stack 223, the second LED stack 233, and the third LED stack 243 are connected to the transistor Tr2, while their cathodes are grounded. The first ohmic electrode 229, the second current spreading layer 239, and the third current spreading layer 249 may be connected to connection pads on the support substrate 251 via connectors connected to the transistor Tr2, and the reflective electrode 225 may be connected to the connection pads of the support substrate 251 and grounded.

[0395] The first LED stack 223, the second LED stack 233, and the third LED stack 243 can be connected to a reflective electrode 225 and grounded. Furthermore, the reflective electrode 225 can be disposed continuously in two or more pixels, or in all pixels. Thus, the reflective electrode 225 can be connected to all LED stacks in the display device. In this manner, by disposing the reflective electrode 225 between the pixel and the support substrate 251, noise in the active matrix drive circuit can be eliminated.

[0396] Although Figure 35 A circuit diagram of an active matrix according to an exemplary embodiment is shown, but the inventive concept is not limited thereto and other circuits may be used.

[0397] According to exemplary embodiments, a plurality of pixels may be formed at a wafer level by using wafer bonding, and thus a display device may be formed without separately mounting light emitting diodes.

[0398] Figure 36 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0399] 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 1350, a third p-transparent electrode 1450, an insulating layer 1270, a first color filter 1370, a second color filter 1470, a first bonding layer 1530, a second bonding layer 1550, and a third bonding layer 1570. In addition, the first LED stack 1230 may include an ohmic contact portion 1230a for ohmic contact.

[0400] The support substrate 1510 supports the LED stacks 1230, 1330, and 1430. The support substrate 1510 may include a circuit on its surface or therein, but the inventive concept is not limited thereto. The support substrate 1510 may include, for example, a Si substrate or a Ge substrate.

[0401] Each of the first LED stack 1230 , the second LED stack 1330 , and the third LED stack 1430 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multi-quantum well structure.

[0402] 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. However, the inventive concept is not limited thereto, and when the light-emitting diode stack 1000 includes a micro-LED, the first LED stack 1230 may emit any one of red, green, and blue light, and the second LED stack 1330 and the third LED stack 1430 may emit different lights among red, green, and blue light, without adversely affecting operation or requiring a color filter due to its small form factor.

[0403] Furthermore, both surfaces of each of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 are an n-type semiconductor layer and a p-type semiconductor layer, respectively. In the illustrated exemplary embodiment, each of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 has an n-type upper surface and a p-type lower surface. Since 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 by chemical etching. However, the inventive concept is not limited thereto, and the semiconductor types of the upper and lower surfaces of each LED stack may be alternately arranged.

[0404] 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. Since the wavelength of light emitted by the first LED stack 1230 is longer than the wavelengths of light emitted by the second LED stack 1330 and the third LED stack 1430, light generated from the first LED stack 1230 can pass through the second LED stack 1330 and the third LED stack 1430 and be emitted to the outside. Furthermore, since the wavelength of light emitted by the second LED stack 1330 is longer than the wavelength of light emitted by the third LED stack 1430, light generated from the second LED stack 1330 can pass through the third LED stack 1430 and be emitted to the outside.

[0405] 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.

[0406] 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 36 As 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.

[0407] Since 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 can cover most of the first LED stack 1230, thereby improving luminous efficiency.

[0408] 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 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 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 generated from the second LED stack 1330 and the third LED stack 1430 and traveling toward the support substrate 1510.

[0409] 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.

[0410] 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.

[0411] 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.

[0412] 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.

[0413] 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.

[0414] A first color filter 1370 may be positioned between the first LED stack 1230 and the second LED stack 1330. A second color filter 1470 may be positioned between the second LED stack 1330 and the third LED stack 1430. The first color filter 1370 transmits light generated from the first LED stack 1230, while reflecting light generated from the second LED stack 1330. The second color filter 1470 transmits light generated from the first LED stack 1230 and the second LED stack 1330, while reflecting 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.

[0415] In some exemplary embodiments, the first color filter 1370 may reflect light generated from the third LED stack 1430 .

[0416] 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. 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 one on top of the other. 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 one on top of the other.

[0417] 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 a light-impermeable layer.

[0418] 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.

[0419] The third bonding layer 1570 bonds the third LED stack 1430 to the second LED stack 1330. Figure 36 As shown in FIG, the third bonding layer 1570 may be adjacent to the second LED stack 1330 and the second color filter 1470. However, the inventive concept is not limited thereto. For example, a transparent conductive layer may be provided on the second LED stack 1330. The third bonding layer 1570 transmits light generated by 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.

[0420] 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.

[0421] 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.

[0422] An insulating layer 1270 is formed on the first LED stack 1230 and patterned to form an opening. For example, a SiO2 layer is formed on the first LED stack 1230, and a photoresist is deposited on the SiO2 layer. A photoresist pattern is then formed by photolithography and development. The SiO2 layer is then patterned using the photoresist pattern as an etching mask, thereby forming the insulating layer 1270.

[0423] 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, etc. 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, etc. The reflective layer 1250b may cover a portion of the ohmic contact layer 1250a or the entirety thereof, as shown in FIG. Figure 37AThe ohmic contact layer 1250 a and the reflective layer 1250 b form a reflective electrode 1250 .

[0424] The reflective electrode 1250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 1230 , and thus, the reflective electrode 1250 will be referred to as a first p-reflective electrode 1250 hereinafter.

[0425] 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 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 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.

[0426] 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 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.

[0427] The first color filter 1370 and the second color filter 1470 are Figure 36 The described first color filter 1370 and the second color filter 1470 are substantially the same, and thus, detailed descriptions thereof will be omitted to avoid redundancy.

[0428] As such, the first LED stack 1230 , the second LED stack 1330 , and the third LED stack 1430 may be grown on different substrates, so their formation order is not limited to a specific order.

[0429] Reference Figure 37D, the first LED stack 1230 is bonded to the supporting substrate 1510 via the first bonding layer 1530. The first bonding layer 1530 may be formed on the supporting substrate 1510 in advance, and the reflective electrode 1250 may be bonded to the first bonding layer 1530 so as to face the supporting substrate 1510. The first substrate 1210 is removed from the first LED stack 1230 by chemical etching or the like. Thus, the upper surface of the n-type semiconductor layer of the first LED stack 1230 is exposed.

[0430] Then, an ohmic electrode 1290 is formed in the exposed region of the first LED stack 1230. To reduce the ohmic contact resistance of the ohmic electrode 1290, the ohmic electrode 1290 may be heat-treated. The ohmic electrode 1290 may be formed in each pixel region to correspond to the pixel region.

[0431] 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 formed on the first LED stack 1230 in advance 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 process or a chemical lift-off process.

[0432] 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 provided on the second LED stack 1330 in advance 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 process or a chemical lift-off process. In this way, a structure such as Figure 36 The light emitting diode stack for a display shown in FIG. 1 has an n-type semiconductor layer of a third LED stack 1430 exposed to the outside.

[0433] A display device according to an exemplary embodiment can be provided by patterning a stack of first LED stack 1230, second LED stack 1330, and third LED stack 1430 on a supporting substrate 1510 in units of pixels, and then connecting the first to third LED stacks to each other through interconnections. Hereinafter, a display device according to an exemplary embodiment will be described.

[0434] Figure 38 is 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.

[0435] Reference Figure 38 and Figure 39 , the display device according to the exemplary embodiment may operate in a passive matrix manner.

[0436] For example, due to Figure 36 The light-emitting diode stack for a display includes a first LED stack 1230, a second LED stack 1330, and a third LED stack 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.

[0437] exist Figure 38 and Figure 39 In the embodiment of the present invention, a pixel includes a first light-emitting diode R, a second light-emitting diode G, and a third light-emitting diode B, each corresponding 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). More specifically, in the first pixel, 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. In this way, the light-emitting diodes R, G, and B in each pixel can be driven independently.

[0438] Furthermore, each of the light emitting diodes R, G, and B may be driven by pulse width modulation or by varying the magnitude of the current, thereby controlling the brightness of each sub-pixel.

[0439] Reference Figure 39 , through patterning Figure 36The light emitting diode stack 1000 is used to form a plurality of pixels, and each pixel is 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.

[0440] The pixels may be arranged in a matrix form, wherein 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 connected to interconnection lines 1710, 1730, and 1750 separated from each other. Here, the interconnection lines 1710, 1730, and 1750 may be used as scan lines Vscan.

[0441] 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.

[0442] 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 ), a portion of the second p transparent electrode 1350 (see also Figure 43H ), a portion of the upper surface of the second LED stack 1330 (see Figure 43J ), a portion of the third p transparent electrode 1450 (see Figure 43H ) and the upper surface of the third LED stack 1430 are exposed to the outside.

[0443] 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.

[0444] The lower insulating layer 1610 may cover the side surface of each pixel. The lower insulating layer 1610 may be formed of a light-transmitting material (e.g., SiO2). In this case, the lower insulating layer 1610 may cover the entire upper surface of the third LED stack 1430. Optionally, the lower insulating layer 1610 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430. In this case, the lower insulating layer 1610 partially exposes the upper surface of the third LED stack 1430.

[0445] 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 (see FIG. Figure 43H ), exposing the ohmic electrode 1290 on the first LED stack 1230; an opening 1610d, exposing the third p transparent electrode 1450; an opening 1610e, exposing the second p transparent electrode 1350; and an opening 1610f, exposing the first p reflective electrode 1250.

[0446] Interconnection lines 1710 and 1750 may be formed on the support substrate 1510 near the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430, and may be disposed on the lower insulating layer 1610 to be insulated from the first p-reflective electrode 1250. A connection portion 1770a connects the third p-transparent electrode 1450 to the reflective electrode 1250, and a connection 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.

[0447] 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 .

[0448] An upper insulating layer 1810 may be disposed on the interconnection lines 1710 and 1750 and the lower insulating layer 1610 to cover the upper surface of the third LED stack 1430. The upper insulating layer 1810 may have an opening 1810a partially exposing the upper surface of the second LED stack 1330.

[0449] 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 cross the upper portion of the interconnection line 1750 and be insulated from the interconnection line 1750 by the upper insulating layer 1810.

[0450] Although the electrodes of each pixel according to the illustrated exemplary embodiment are described as being connected to a data line and a scan line, various embodiments are possible. Furthermore, although interconnects 1710 and 1750 are described as being formed on lower insulating layer 1610 and interconnect 1730 is formed on upper insulating layer 1810, the inventive concept is not limited thereto. For example, each of interconnects 1710, 1730, and 1750 may be formed on lower insulating layer 1610 and covered by upper insulating layer 1810, which may have an opening exposing interconnect 1730. In this structure, connection portion 1730a may pass through the opening of upper insulating layer 1810 to connect the upper surface of second LED stack 1330 to interconnect 1730.

[0451] Optionally, interconnect lines 1710, 1730 and 1750 can be formed inside the supporting substrate 1510, and the connecting portions 1710a, 1730a and 1750a on the lower insulating layer 1610 can 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 interconnect lines 1710, 1730 and 1750.

[0452] 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.

[0453] First, prepare Figure 36 The light emitting diode stack 1000 described in .

[0454] 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.

[0455] By considering the area of ​​the third LED stack 1430 to be etched in a subsequent process, the rough surface 1430 a may be partially formed in each pixel area, but is not limited thereto. Alternatively, the rough surface 1430 a may be formed over the entire upper surface of the third LED stack 1430 .

[0456] 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 43B As shown in , the third LED stack 1430 may be left with a rectangular shape or a square shape. The third LED stack 1430 may have a plurality of recesses along its edges.

[0457] Reference Figure 43C , the upper surface of the second LED stack 1330 is exposed by removing the exposed third p transparent electrode 1450 in the area except for one recess of the third LED stack 1430. Therefore, the upper surface of the second LED stack 1330 is exposed around the third LED stack 1430 and in the recesses except for the remaining recess of the third p transparent electrode 1450 portion.

[0458] Reference Figure 43D , the second p transparent electrode 1350 is exposed by removing the exposed second LED stack 1330 in a region other than another recess of the third LED stack 1430 .

[0459] Reference Figure 43E By removing the exposed second p-type transparent electrode 1350 in a region other than the recess of the third LED stack 1430, the ohmic electrode 1290 is exposed along with the upper surface of the first LED stack 1230. 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.

[0460] 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.

[0461] Reference Figure 43G , by patterning the reflective electrode 1250 to form a linear interconnection line. Here, the supporting substrate 1510 may be exposed. The reflective electrode 1250 may connect pixels arranged in a column among pixels arranged in a matrix to each other (see FIG. Figure 39 ).

[0462] 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 first LED stack 1230, the second LED stack 1330, and the third LED stack 1430, as well as the reflective electrode 1250. 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. Optionally, when the lower insulating layer 1610 includes a distributed Bragg reflector, the lower insulating layer 1610 may at least partially expose the upper surface of the third LED stack 1430 so that light can be emitted to the outside.

[0463] 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.

[0464] Reference Figure 43I , interconnects 1710, 1750 and connectors 1710a, 1750a, 1770a, and 1770b are formed. These can be formed using a lift-off process, for example. Interconnects 1710 and 1750 are insulated from reflective electrode 1250 by lower insulating layer 1610. Connector 1710a electrically connects third LED stack 1430 to interconnect 1710, and connector 1750a electrically connects ohmic electrode 1290 to interconnect 1750, thereby electrically connecting first LED stack 1230 to interconnect 1750. Connector 1770a electrically connects third p-type transparent electrode 1450 to first p-type reflective electrode 1250, and connector 1770b electrically connects second p-type transparent electrode 1350 to first p-type reflective electrode 1250.

[0465] Reference Figure 43J , so that the 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, allowing light to be emitted to the outside.

[0466] Reference Figure 43K , forming interconnection line 1730 and connection portion 1730a. Interconnection line 1730 and connection portion 1730a can be formed using a lift-off process, etc. Interconnection line 1730 is disposed 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 extend over the upper portion of interconnection line 1750 and be insulated from interconnection line 1750 by upper insulating layer 1810.

[0467] In this way, it can form Figure 40 In addition, as shown in the pixel area Figure 39 As shown in FIG, a plurality of pixels may be formed on a supporting substrate 1510 and 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.

[0468] 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 stack shown in FIG. 1 is fabricated in various ways so as to operate in a passive matrix manner.

[0469] 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 lower insulating layer 1610 to connect the second LED stack 1330 to the interconnection line 1730. Alternatively, the interconnection lines 1710, 1730, and 1750 may be disposed inside the support substrate 1510.

[0470] Figure 44is 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.

[0471] 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, a voltage is applied to the corresponding light-emitting diode. In addition, the corresponding capacitor is charged according to the value of Vdata1 to Vdata3. Since the on state of transistor Tr2 can be maintained by the charging voltage of the capacitor, the voltage of the capacitor can be maintained even when the power supplied to Vrow1 is cut off, and the voltage of the capacitor 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 continuously supplied by Vdd, so that continuous light emission can be achieved.

[0472] 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.

[0473] The light emitting diodes LED1 to LED3 may respectively correspond to the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 stacked in one pixel. Anodes of the first to third LED stacks are connected to the transistor Tr2, and cathodes thereof are grounded.

[0474] 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 their cathodes as being grounded, the inventive concept is not limited thereto, and the anodes of the light-emitting diodes may be connected to the current source Vdd, and their cathodes may be connected to different transistors.

[0475] 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 pixel among a plurality of pixels arranged on a supporting substrate 1511.

[0476] 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 substantially similar to the reference Figures 39 to 42Described pixels.

[0477] The cathode of the third LED stack is connected to the support base 1511 through the connection portion 1711a. Figure 45 As shown in , the cathode of the third LED stack can be grounded by being electrically connected to the support substrate 1511. The cathodes of the second and first LED stacks can also be grounded by being electrically connected to the support substrate 1511 via the connection portions 1731a and 1751a.

[0478] The reflective electrode is connected to the transistor Tr2 located inside the supporting substrate 1511 (see FIG. Figure 44 The third p-type transparent electrode and the second p-type transparent electrode are also connected to the transistor Tr2 located inside the supporting substrate 1511 through the connecting portions 1771a and 1731b (see FIG. Figure 44 ).

[0479] In this way, as Figure 44 As shown in , the first to third LED stacks are connected to each other, thereby configuring a circuit for active matrix driving.

[0480] 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.

[0481] In addition, although Figure 36 Reflective electrode 1250, second p-transparent electrode 1350, and third p-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 size is 200 μm or less, even if a separate ohmic contact layer is not formed 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.

[0482] In addition, although the first LED stack 1230, the second LED stack 1330 and the third LED stack 1430 are combined with each other via the bonding layers 1530, 1550 and 1570, the inventive concept is not limited thereto, and the first LED stack 1230, the second LED stack 1330 and the third LED stack 1430 can be connected to each other in various orders and using various structures.

[0483] According to exemplary embodiments, since multiple pixels can be formed at the wafer level using the light-emitting diode stack 1000 for a display, it is possible to avoid individually mounting light-emitting diodes. Furthermore, the light-emitting diode stack according to exemplary embodiments has a structure in which the first LED stack 1230, the second LED stack 1330, and the third LED stack 1430 are stacked vertically, thereby ensuring the area of ​​the 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.

[0484] Figure 46 is a schematic cross-sectional view of a light emitting diode stack for a display according to an exemplary embodiment.

[0485] 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 2350, a third p-transparent electrode 2450, an insulating layer 2270, a first bonding layer 2530, a second bonding layer 2550, and a third bonding layer 2570. In addition, the first LED stack 2230 may include an ohmic contact portion 2230a for ohmic contact.

[0486] In general, light emitted from the second LED stack may generate light from the first LED stack, and light emitted from the third LED stack may generate light from the second LED stack. Thus, color filters may be provided between the second LED stack and the first LED stack, and between the third LED stack and the second LED stack.

[0487] However, although color filters can prevent interference of light, forming the color filters increases manufacturing complexity. A display device according to an exemplary embodiment can suppress generation of secondary light between LED stacks without disposing a color filter therebetween.

[0488] Thus, in some exemplary embodiments, interference of light between LED stacks may be reduced by controlling the bandgap of each LED stack, as will be described in more detail below.

[0489] The support substrate 2510 supports the semiconductor stacks 2230, 2330, and 2430. The support substrate 2510 may include a circuit on or in its surface, 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.

[0490] Each of the first LED stack 2230 , the second LED stack 2330 , and the third LED stack 2430 includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer interposed therebetween. The active layer may have a multi-quantum well structure.

[0491] The wavelength of light L1 generated from the first LED stack 2230 is longer than the wavelength of light L2 generated from the second LED stack 2330, and the wavelength of light L2 generated from the second LED stack 2330 is longer than the wavelength of light L3 generated from the third LED stack 2430. However, the inventive concept is not limited thereto, and when the light emitting diode stacks include micro-LEDs, the light generated from the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 may have any wavelength range without adversely affecting operation due to their small form factors.

[0492] 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 LED stack 2330 and the third LED stack 2430 may include a GaInN base well layer.

[0493] 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.

[0494] Both surfaces of each of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 are respectively an n-type semiconductor layer and a p-type semiconductor layer. Figure 46 , each of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 is described as having an n-type upper surface and a p-type lower surface. Since 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 may be alternately formed.

[0495] 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 pass through the second and third LED stacks 2330, 2430, and be emitted to the outside. 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 pass through the third LED stack 2430 and be emitted to the outside. Light L3 generated in the third LED stack 2430 is emitted directly from the third LED stack 2430.

[0496] In an exemplary embodiment, the band gap of the n-type semiconductor layer of the first LED stack 2230 may be 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 due to the light generated from the second LED stack 2330.

[0497] Furthermore, the band gap of the n-type semiconductor layer of the second LED stack 2330 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 is 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 is 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 is reduced by the light generated from the third LED stack 2430.

[0498] 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.

[0499] According to an exemplary embodiment, it is possible to reduce interference of light between the LED stacks 2230, 2330, and 2430 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, which can avoid the need for other components (such as color filters). For example, the intensity of light generated and emitted to the outside from the second LED stack 2330 can 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 and emitted to the outside from the third LED stack 2430 can 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 and emitted to the outside from the third LED stack 2430 can 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, a display device free from color contamination caused by interference of light can be realized.

[0500] 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.

[0501] The ohmic contact layer 2250a partially contacts the p-type semiconductor layer of the first LED stack 2230. To prevent light from being absorbed by the ohmic contact layer 2250a, the area where the ohmic contact layer 2250a contacts the p-type semiconductor layer may not exceed approximately 50% of the 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.

[0502] Since the reflective layer 2250b covers the insulating layer 2270, an omnidirectional reflector can be formed by the stacked structure of the reflective layer 2250b, the first LED stack 2230 having a relatively high refractive index, and the insulating layer 2270 having a relatively low refractive index. The reflective layer 2250b may cover approximately 50% or more of the area of ​​the first LED stack 2230, or may cover most of the first LED stack 2230, thereby improving luminous efficiency.

[0503] 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 LED stack 2330 and the third LED stack 2430 and traveling toward the support substrate 2510.

[0504] 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.

[0505] 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.

[0506] 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.

[0507] 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.

[0508] 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.

[0509] The first bonding layer 2530 bonds the first LED stack 2230 to the supporting 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 a light-impermeable layer.

[0510] The second bonding layer 2550 bonds the second LED stack 2330 to the first LED stack 2230. Figure 46 As 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, etc.

[0511] 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 by the first LED stack 2230 and the second LED stack 2330 and may be formed of, for example, light-transmitting spin-on glass.

[0512] 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 .

[0513] 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.

[0514] 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.

[0515] An insulating layer 2270 is formed on the first LED stack 2230 and patterned to form an opening therein. For example, a SiO2 layer is formed on the first LED stack 2230, and a photoresist is deposited on the SiO2 layer, followed by photolithography and development 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 opening.

[0516] 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 a portion or all of the ohmic contact layer 2250a. The ohmic contact layer 2250a and the reflective layer 2250b form the reflective electrode 2250.

[0517] The reflective electrode 2250 forms an ohmic contact with the p-type semiconductor layer of the first LED stack 2230 , and thus, the reflective electrode 2250 will be referred to as a first p-reflective electrode 2250 hereinafter.

[0518] 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 may 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.

[0519] Reference Figure 47CA third LED stack 2430 is formed 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 can 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.

[0520] As such, the first LED stack 2230 , the second LED stack 2330 , and the third LED stack 2430 are grown on different substrates, so their formation order is not limited to a specific order.

[0521] Reference Figure 47D , the first LED stack 2230 is bonded to the supporting substrate 2510 via the first bonding layer 2530. The first bonding layer 2530 may be formed on the supporting substrate 2510 in advance, and the reflective electrode 2250 may be bonded to the first bonding layer 2530 so as to face the supporting substrate 2510. The first substrate 2210 is removed from the first LED stack 2230 by chemical etching or the like. Thus, the upper surface of the n-type semiconductor layer of the first LED stack 2230 is exposed.

[0522] Then, an ohmic electrode 2290 is formed in the exposed region of the first LED stack 2230. To reduce the ohmic contact resistance of the ohmic electrode 2290, the ohmic electrode 2290 may be heat-treated. The ohmic electrode 2290 may be formed in each pixel region to correspond to the pixel region.

[0523] Reference Figure 47E The second LED stack 2330 is bonded to the first LED stack 2230 having the ohmic electrode 2290 formed thereon via the second bonding layer 2550. The second p-type 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 formed in advance on the first LED stack 2230 so that the second p-type transparent electrode 2350 can face and bond 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.

[0524] 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 formed on the second LED stack 2330 in advance so that the third p transparent electrode 2450 may face and bond 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 The light emitting diode stack for a display shown in FIG. 1 has an n-type semiconductor layer of a third LED stack 2430 exposed to the outside.

[0525] The display device can be formed by patterning a stack of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 provided on the supporting substrate 2510 in a pixel unit, and then connecting the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 to each other through interconnection. However, the inventive concept is not limited thereto. For example, the display device can be manufactured by dividing the stack of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 into separate units and transferring the stack of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430 to another supporting substrate (such as a printed circuit board).

[0526] 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.

[0527] 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.

[0528] Figure 46 The light-emitting diode stack for a display shown in FIG has a structure including a first LED stack 2230, a second LED stack 2330, and a third LED stack 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.

[0529] Reference Figure 48 and Figure 49 , a pixel includes a first light-emitting diode R, a second light-emitting diode G, and a third light-emitting diode B, each of which can correspond 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 example, in a first pixel, 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. In this way, the light-emitting diodes R, G, and B in each pixel can be driven independently.

[0530] Furthermore, each of the light emitting diodes R, G, and B may be driven with pulse width modulation or by varying the magnitude of current, thereby controlling the brightness of each sub-pixel.

[0531] Reference Figure 49 , through patterning Figure 46 A plurality of pixels are formed by stacking the components, 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.

[0532] The pixels may be arranged in a matrix form, wherein the anodes of the light emitting diodes R, G, and B of each pixel are commonly connected to the reflective electrode 2250, and their cathodes are connected to interconnection lines 2710, 2730, and 2750 spaced apart from each other. Here, the interconnection lines 2710, 2730, and 2750 may be used as scan lines Vscan.

[0533] 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.

[0534] 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 ), a portion of the second p transparent electrode 2350 (see Figure 53H ), a portion of the upper surface of the second LED stack 2330 (see Figure 53J ), a portion of the third p transparent electrode 2450 (see Figure 53H) and the upper surface of the third LED stack 2430 are exposed to the outside.

[0535] 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 .

[0536] The lower insulating layer 2610 may cover the side surface 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. Optionally, the lower insulating layer 2610 may include a distributed Bragg reflector to reflect light traveling toward the side surfaces of the first LED stack 2230, the second LED stack 2330, and the third LED stack 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-like insulating layer that absorbs light. In addition, an electrically floating metal reflective layer may be formed on the lower insulating layer 2610 to reflect light emitted through the side surfaces of the first LED stack 2230, the second LED stack 2330, and the third LED stack 2430.

[0537] 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 FIG. Figure 53H ), exposing the ohmic electrode 2290 on the first LED stack 2230; an opening 2610d, exposing the third p transparent electrode 2450; an opening 2610e, exposing the second p transparent electrode 2350; and an opening 2610f, exposing the first p reflective electrode 2250.

[0538] Interconnection lines 2710 and 2750 may be formed on the supporting substrate 2510 near the first LED stack 2230, the second LED stack 2330, and the third LED stack 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.

[0539] 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 .

[0540] An upper insulating layer 2810 may be disposed on the interconnection lines 2710 and 2750 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.

[0541] 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 cross the upper portion of the interconnection line 2750 and be insulated from the interconnection line 2750 by the upper insulating layer 2810.

[0542] 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 interconnects 2710 and 2750 are described as being formed on lower insulating layer 2610, and interconnect 2730 is described as being formed on upper insulating layer 2810, the inventive concept is not limited thereto. For example, all of interconnects 2710, 2730, and 2750 may be formed on lower insulating layer 2610 and may be covered by upper insulating layer 2810, which may have an opening exposing interconnect 2730. In this manner, connection portion 2730a may pass through the opening of upper insulating layer 2810, connecting the upper surface of second LED stack 2330 to interconnect 2730.

[0543] Optionally, interconnect lines 2710, 2730 and 2750 can be formed inside the supporting substrate 2510, and the connecting 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 interconnect lines 2710, 2730 and 2750.

[0544] 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.

[0545] 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.

[0546] First, prepare Figure 46 The light emitting diode stack 2000 described in .

[0547] 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.

[0548] 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 .

[0549] 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 FIG, the third LED stack 2430 may be retained to have a rectangular shape or a square shape. The third LED stack 2430 may have a plurality of recesses formed along its edge.

[0550] 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 area 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 remaining recess of the third p transparent electrode 2450 portion.

[0551] 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.

[0552] Reference Figure 53E By removing the exposed second p-type transparent electrode 2350 in the region other than 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.

[0553] 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.

[0554] Reference Figure 53G , a linear interconnection line is formed by patterning the reflective electrode 2250. Here, the supporting substrate 2510 may be exposed. The reflective electrode 2250 may connect pixels arranged in a column among pixels arranged in a matrix to each other (see FIG. Figure 49 ).

[0555] 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 can 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 can substantially cover the entire upper surface of the third LED stack 2430. Optionally, the lower insulating layer 2610 can include a distributed Bragg reflector. In this case, the lower insulating layer 2610 can partially expose the upper surface of the third LED stack 2430, so that light is emitted to the outside.

[0556] The lower insulating layer 2610 may include an opening 2610a exposing the third LED stack 2430, an opening 2610b exposing the second LED stack 2330, an opening 2610c exposing the ohmic electrode 2290, an opening 2610d exposing the third p-transparent electrode 2450, an opening 2610e exposing the second p-transparent electrode 2350, and an opening 2610f exposing the reflective electrode 2250. The opening 2610f exposing the reflective electrode 2250 may be formed individually or in plurality.

[0557] Reference Figure 53I Interconnections 2710 and 2750 and connectors 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. Connector 2710a electrically connects third LED stack 2430 to interconnection 2710, and connector 2750a electrically connects ohmic electrode 2290 to interconnection 2750, thereby electrically connecting first LED stack 2230 to interconnection 2750. Connector 2770a electrically connects third p-type transparent electrode 2450 to first p-type reflective electrode 2250, and connector 2770b electrically connects second p-type transparent electrode 2350 to first p-type reflective electrode 2250.

[0558] Reference Figure 53J , so that the upper insulating layer 2810 (see Figure 51 and Figure 52 ) covers the interconnect lines 2710, 2750 and the connection portions 2710a, 2750a, 2770a, and 2770b. The upper insulating layer 2810 can 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 can be formed of, for example, silicon oxide or silicon nitride, and can include a distributed Bragg reflector. When the upper insulating layer 2810 includes a distributed Bragg reflector, the upper insulating layer 2810 can expose at least a portion of the upper surface of the third LED stack 2430, thereby emitting light to the outside.

[0559] Reference Figure 53K , forming interconnection line 2730 and connection portion 2730a. Interconnection line 2730 and connection portion 2730a can be formed by a lift-off process, etc. Interconnection line 2730 is disposed 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 extend over the upper portion of interconnection line 2750 and be insulated from interconnection line 2750 by upper insulating layer 2810.

[0560] 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.

[0561] Although the method of manufacturing a display device that can operate in a passive matrix manner is described above, the inventive concept is not limited thereto. More specifically, a display device according to an exemplary embodiment can be operated using a passive matrix. Figure 46 The light emitting diode stack shown in FIG. 1 is fabricated in various ways so as to operate in a passive matrix manner.

[0562] 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 lower insulating layer 2610 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.

[0563] Figure 54 is a schematic circuit diagram of a display device according to another exemplary embodiment. Figure 54 The circuit diagram relates to a display device driven in an active matrix manner.

[0564] 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, a voltage is applied to the corresponding light-emitting diode. In addition, the corresponding capacitor is charged according to the value of Vdata1 to Vdata3. Since the conductive state of transistor Tr2 can be maintained by the charging voltage of the capacitor, the voltage of the capacitor can be maintained even when the power supply to Vrow1 is cut off, and the voltage of the capacitor 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 continuously supplied by Vdd, so that continuous light emission can be achieved.

[0565] 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.

[0566] 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.

[0567] 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.

[0568] Figure 55 25 is a schematic plan view 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.

[0569] 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 a 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.

[0570] The cathode of the third LED stack 2430 is connected to the support base 2511 through the connection portion 2711a. Figure 54 As shown in FIG, the cathode of the third LED stack 2430 can 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 can also be grounded by being electrically connected to the support substrate 2511 via the connection portions 2731a and 2751a.

[0571] The reflective electrode is connected to the transistor Tr2 located inside the supporting substrate 2511 (see FIG. Figure 54 The third p-type transparent electrode and the second p-type transparent electrode are also connected to the transistor Tr2 located inside the supporting substrate 2511 through the connecting portions 2771a and 2731b (see FIG. Figure 54 ).

[0572] In this way, as Figure 54 As shown in , the first to third LED stacks are connected to each other, thereby forming a circuit for active matrix driving.

[0573] Although Figure 55 Pixels having electrical connections for active matrix driving according to exemplary embodiments are illustrated, 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.

[0574] In addition, although 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 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, and the ohmic electrode 2290 is described as forming ohmic contact with the n-type semiconductor layer of the first LED stack 2230, but no separate ohmic contact layer is provided for the n-type semiconductor layer of each of the second LED stack 2330 and the third LED stack 2430. Although current diffusion is less difficult even without forming a separate ohmic contact layer in the n-type semiconductor layer when the pixel has a small size of 200 μm or less, 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.

[0575] In addition, although Figure 46 It is shown that the first LED stack 2230, the second LED stack 2330 and the third LED stack 2430 are bonded to each other via a bonding layer, but the inventive concept is not limited thereto, and 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.

[0576] According to exemplary embodiments, because multiple pixels can be formed at the wafer level using the LED stack 2000 for a display, the need to individually mount LEDs can be avoided. Furthermore, the LED 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 the area of ​​sub-pixels within a limited pixel area. Furthermore, the LED stack according to exemplary embodiments allows 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.

[0577] 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 according to an exemplary embodiment.

[0578] 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.

[0579] 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.

[0580] 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.

[0581] 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 emit light from the first LED stack 3230, the second subpixel G is configured to emit light from the second LED stack 3330, and the third subpixel B is configured to emit light from the third LED stack 3430. The first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 can be driven independently.

[0582] 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 .

[0583] A portion of 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 a portion of 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, a portion of 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 a portion of the light generated from the second LED stack 3330 may be emitted to the outside without passing through the third LED stack 3430.

[0584] The area through which light R of the first LED stack 3230 is emitted, the area through which light G of the second LED stack 3330 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.

[0585] However, the inventive concept is not limited thereto. Optionally, 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.

[0586] 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.

[0587] 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 by being absorbed 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.

[0588] Figure 58 is a schematic circuit diagram of a display device according to an exemplary embodiment.

[0589] 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.

[0590] For example, the driving circuit may include at least two transistors Tr1 and 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, a voltage is applied to the corresponding light-emitting diode. In addition, the corresponding capacitor is charged according to the value of Vdata1 to Vdata3. Since the on-state of transistor Tr2 can be maintained by the charging voltage of the capacitor, the voltage of the capacitor can be maintained even when the power supplied to Vrow1 is cut off, and the voltage of the capacitor 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. Current can be continuously supplied by Vdd, and therefore, light can be continuously emitted.

[0591] Transistors Tr1 and Tr2 and a capacitor may be formed within the support substrate 3510. Here, the light-emitting diodes LED1 to LED3 may correspond to the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430, respectively, stacked in one pixel. The anodes of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 are connected to the transistor Tr2, while their cathodes are grounded. The cathodes of the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430 may be commonly grounded, for example.

[0592] 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.

[0593] 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, while their cathodes may be connected to the scan line in common. In another 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 scan lines, while their cathodes may be connected to the data line in common.

[0594] Furthermore, each of the LED stacks 3230, 3330, and 3430 can be driven by 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 light R, G, and B from 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 3430, thereby emitting light with higher intensity at the same current density. Furthermore, since 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 .

[0595] 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 Figure 59A Schematic cross-sectional views taken along lines AA, BB, CC and DD.

[0596] 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.

[0597] Reference Figure 59A 、 Figure 59B 、 Figure 60A 、 Figure 60B 、 Figure 60C and Figure 60DThe pixel includes a substrate 3210, a distributed Bragg reflector 3220, an insulating layer 3250, through holes 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.

[0598] 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.

[0599] 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.

[0600] 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.

[0601] 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 conductive type and the second conductive type may be reversely changed.

[0602] 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 some areas on the first LED stack 3230 so that the first LED stack 3230 partially overlaps the second LED stack 3330. The third LED stack 3430 is disposed in some areas on the second LED stack 3330 so that the second LED stack 3330 partially overlaps the third LED stack 3430. Therefore, a portion of the 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, a portion of the light generated from the second LED stack 3330 can be emitted to the outside without passing through the third LED stack 3430.

[0603] 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.

[0604] 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.

[0605] Through holes 3270a, 3270b, 3270c are formed through the substrate 3210. The through holes 3270a, 3270b, 3270c may be formed through the first LED stack 3230. The through holes 3270a, 3270b, 3270c may be formed of a conductive paste or by electroplating.

[0606] The insulating layer 3250 is disposed between the through holes 3270 a , 3270 b , and 3270 c and sidewalls of the through hole 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 .

[0607] 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.

[0608] 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 .

[0609] 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.

[0610] The first -2 ohm electrode 3290 b may be connected to the through hole 3270 a so that the through hole 3270 a may be electrically connected to the second conductive type semiconductor layer 3230 b .

[0611] 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 59A As 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.

[0612] 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.

[0613] 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 .

[0614] 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 may include a reflective layer 3450a and a barrier layer 3450b. The reflective layer 3450a reflects light generated from the third LED stack 3430 to improve the luminous efficiency of the third LED stack 3430. The barrier layer 3450b 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 may be formed of a transparent conductive oxide (such as a conductive oxide semiconductor layer).

[0615] 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.

[0616] The first bonding layer 3530 bonds the second LED stack 3330 to the first LED stack 3230. As shown in the drawings, 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 a light-impermeable 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, polyparaxylene, benzocyclobutene (BCB), etc., and examples of inorganic materials may include Al2O3, SiO2, SiN x Etc. 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.

[0617] 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-ohm electrode 3450 to bond the second LED stack 3330 to the third 2-ohm 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.

[0618] 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, a 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.

[0619] In this case, 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, 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 light generated from the first LED stack 3230 may be longer than that of light generated from the second LED stack 3330.

[0620] 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 .

[0621] When the first bonding layer 3530 and the second bonding layer 3550 are formed of a light-impermeable material, reflective layers are respectively 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 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.

[0622] 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 .

[0623] The upper insulating layer 3610 has openings exposing the first through hole 3270a, the second through hole 3270b, the third through hole 3270c, and 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.

[0624] The upper insulating layer 3610 may be formed of any insulating material, such as silicon oxide or silicon nitride, but is not limited thereto.

[0625] 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.

[0626] 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.

[0627] The connector 3720 can electrically connect the second 2-ohm electrode 3350 (e.g., the barrier layer 3350b) to the second through-hole 3270b. The connector 3730 can electrically connect the third 2-ohm electrode (e.g., the barrier layer 3450b) to the third through-hole 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.

[0628] 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 from 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 from 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.

[0629] 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 exposing the first through hole 3270a, the second through hole 3270b, and the third through hole 3270c, and may further include an opening exposing the lower surface of the substrate 3210.

[0630] 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 through holes 3270a, 3270b, and 3270c through the openings of the lower insulating layer 3750, and the electrode pad 3770d is connected to the substrate 3210.

[0631] 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 to provide an electrode pad 3770d for each pixel.

[0632] The electrode pads 3770a, 3770b, 3770c, and 3770d are coupled to the circuit board 3510, thereby improving the display device.

[0633] Next, a method of manufacturing a display apparatus according to an exemplary embodiment will be described.

[0634] Figures 61A to 68B 1 and 2 are 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 a line shown in each corresponding plan view.

[0635] 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.

[0636] 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 .

[0637] Then, an insulating layer 3250 is formed to cover the sidewalls of the groove, and through holes 3270a, 3270b, and 3270c are formed to fill the groove. The through holes 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.

[0638] Reference Figure 62A and Figure 62B , the second LED stack 3330 and the second -2 ohm electrode 3350 may be bonded to the first LED stack 3230 via the first bonding layer 3530 .

[0639] 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 (e.g., a GaAs substrate) on which an AlGaInP-based semiconductor layer may be grown, or a substrate (e.g., a sapphire substrate) on which an AlGaInN-based semiconductor layer may be grown. 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 barrier layer 3350b and a reflective layer 3350a that reflects light generated by the second LED stack 3330.

[0640] The second -2 ohm electrode 3350 is positioned 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.

[0641] 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 .

[0642] Reference Figure 63A and Figure 63B, the third LED stack 3430 and the third -2 ohm electrode 3450 may be bonded to the second LED stack 3330 via the second bonding layer 3550 .

[0643] 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 may be grown and is different from the first substrate 3210. The composition ratio of AlGaInN used in the third LED stack 3430 may 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 barrier layer 3450b and a reflective layer 3450a that reflects light generated by the third LED stack 3430.

[0644] The third -2 ohmic 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.

[0645] According to exemplary embodiments, an insulating layer and a reflective layer may be further formed on the second LED stack 3330 before forming the second bonding layer 3550 .

[0646] 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, a recess is formed on the third LED stack 3430 to expose the blocking layer 3450 b through the recess.

[0647] 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.

[0648] 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 .

[0649] The second-2 ohmic electrode 3350 is exposed by patterning the second LED stack 3330. The second LED stack 3330 may include a recess, and the second-2 ohmic electrode 3350 (eg, the barrier layer 3350b) may be exposed through the recess.

[0650] 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 through hole 3270a, the second through hole 3270b, and the third through hole 3270c are also exposed together with the first LED stack 3230.

[0651] 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.

[0652] Furthermore, the pixel regions are separated from each other by patterning the first LED stack 3230. This defines the region of the first subpixel R. The distributed Bragg reflector 3220 may also be separated. Alternatively, the distributed Bragg reflector 3220 may be provided continuously for multiple pixels without being separated. Furthermore, the first conductive type semiconductor layer 3230a may also be provided continuously for multiple pixels.

[0653] 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 of, 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 of, 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 through hole 3270a. On the other hand, 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 through hole 3270a.

[0654] 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 extended 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.

[0655] 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.

[0656] The upper insulating layer 3610 may have: an opening 3610a exposing the first -1 ohm electrode 3290a; openings 3610b, 3610c exposing the blocking layers 3350b, 3450b; openings 3610d, 3610e exposing the second through hole 3270b and the third through hole 3270c; and openings 3610f, 3610g exposing 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.

[0657] 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.

[0658] 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 can 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.

[0659] The connector 3720 electrically connects the second-2 ohm electrode 3350 to the second through hole 3270b, and the connector 3730 electrically connects the third-2 ohm electrode 3450 to the third through hole 3270c. The connectors 3720 and 3730 are provided on the upper insulating layer 3610 to prevent short circuits with the first LED stack 3230, the second LED stack 3330, and the third LED stack 3430.

[0660] 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 using 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 using different processes.

[0661] 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 through hole 3270a, the second through hole 3270b, and the third through hole 3270c, and may further have an opening exposing the lower surface of the substrate 3210.

[0662] 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 through hole 3270a, the second through hole 3270b, and the third through hole 3270c, respectively, and the electrode pad 3770d is connected to the substrate 3210.

[0663] Thus, the electrode pad 3770a is electrically connected to the second conductive semiconductor layer 3230b of the first LED stack 3230 through the first through-hole 3270a, the electrode pad 3770b is electrically connected to the second conductive semiconductor layer 3330b of the second LED stack 3330 through the second through-hole 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 through-hole 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 electrically connected in common to the electrode pad 3770d.

[0664] 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.

[0665] Figure 69 is a cross-sectional view of a light emitting diode pixel for a display according to another exemplary embodiment.

[0666] 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.

[0667] 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.

[0668] 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 Figure 70 A cross-sectional view taken along line GG and line HH.

[0669] Reference Figure 70 、 Figure 71A and Figure 71B 59, 51 and 52, 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. Figure 60A 、 Figure 60B and Figure 60CThe first through hole 3270 a , the second through hole 3270 b , and the third through hole 3270 c may be provided outside the second LED stack 3330 and the third LED stack 3430 .

[0670] 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.

[0671] 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.

[0672] On the other hand, Figure 71A and Figure 71B As shown in FIG, a recess may be formed on the third LED stack 3430 to expose the third-2 ohmic electrode 3450, and recesses 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 through hole 3270b and the third through hole 3270c through connectors 3720 and 3730, respectively.

[0673] Furthermore, a recess 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 recesses 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.

[0674] 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.

[0675] According to example embodiments, a plurality of pixels may be formed at a wafer level through wafer bonding, and thus, a process of individually mounting light emitting diodes may be avoided or significantly reduced.

[0676] Furthermore, since the through holes 3270a, 3270b, and 3270c are formed in the substrate 3210 and used as current paths, it is not necessary to remove the substrate 3210. Therefore, the growth substrate used to grow the first LED stack 3230 can be used as the substrate 3210 without being removed from the first LED stack 3230.

[0677] Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concept is not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements that will be apparent to those skilled in the art.

Claims

1. A light emitting diode stack for a display, comprising: Support substrate; A first LED stack is located on the supporting substrate; A second LED stack, located on the first LED stack; A third LED stack, located on the second LED stack; A first color filter disposed between the first LED stack and the second LED stack; a second color filter disposed between the second LED stack and the third LED stack; A first bonding layer disposed between the support substrate and the first LED stack; a second bonding layer disposed between the first LED stack and the first color filter; a third bonding layer disposed between the second LED stack and the second color filter; A first p reflective electrode is located between the first bonding layer and the first LED stack and is in ohmic contact with the p-type semiconductor layer of the first LED stack; A second p transparent electrode is located between the first color filter and the second LED stack and is in ohmic contact with the p-type semiconductor layer of the second LED stack; a third p transparent electrode, located between the second color filter and the third LED stack, and in ohmic contact with the p-type semiconductor layer of the third LED stack; a lower insulating layer covering the first LED stack, the second LED stack, and the third LED stack, and having an opening exposing the first p reflective electrode, the second p transparent electrode, and the third p transparent electrode; a connecting member, disposed on the lower insulating layer and electrically connected to the first p reflective electrode, the second p transparent electrode and the third p transparent electrode through the opening, so as to connect the first p reflective electrode with the second p transparent electrode and connect the first p reflective electrode with the third p transparent electrode, wherein 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 toward the outside through the third LED stack.

2. The light emitting diode stack for a display 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 light emitting diode stack for a display according to claim 1, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. The first color filter and the second color filter are respectively low-pass filters, band-pass filters or band-stop filters.

4. The light emitting diode stack for a display according to claim 3, wherein: The first color filter and the second color filter are both distributed Bragg reflectors.

5. The light emitting diode stack for a display according to claim 1, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. The second bonding layer transmits light generated from the first LED stack, The third bonding layer transmits light generated from the first LED stack and the second LED stack.

6. The light emitting diode stack for a display according to claim 5, wherein: The first bonding layer, the second bonding layer and the third bonding layer are transparent inorganic insulating films, transparent organic insulating films or transparent conductive films.

7. The light emitting diode stack for a display according to claim 5, wherein: Light generated from the first LED stack is emitted to the outside through the second p transparent electrode and the third p transparent electrode. Light generated from the second LED stack is emitted toward the outside through the third p transparent electrode.

8. The light emitting diode stack for a display according to claim 7, wherein: The second bonding layer contacts the n-type semiconductor layer of the first LED stack, The third bonding layer contacts the n-type semiconductor layer of the second LED stack.

9. A light emitting diode stack for a display, comprising: Support substrate; A first LED stack is located on the supporting substrate; A second LED stack, located on the first LED stack; A third LED stack, located on the second LED stack; A first color filter disposed between the first LED stack and the second LED stack; a second color filter disposed between the second LED stack and the third LED stack; A first bonding layer disposed between the support substrate and the first LED stack; a second bonding layer disposed between the first color filter and the second LED stack; a third bonding layer disposed between the second LED stack and the second color filter; A first n-type reflective electrode is located between the first bonding layer and the first LED stack and is in ohmic contact with the n-type semiconductor layer of the first LED stack. a first p transparent electrode, located between the first LED stack and the first color filter and in ohmic contact with the p-type semiconductor layer of the first LED stack; A second p transparent electrode is located between the second LED stack and the third bonding layer and is in ohmic contact with the p-type semiconductor layer of the second LED stack; a third p transparent electrode, located between the second color filter and the third LED stack, and in ohmic contact with the p-type semiconductor layer of the third LED stack; a lower insulating layer covering the first LED stack, the second LED stack, and the third LED stack, and having an opening exposing the first p transparent electrode, the second p transparent electrode, and the third p transparent electrode; a connecting member, disposed on the lower insulating layer and electrically connected to the first p transparent electrode, the second p transparent electrode and the third p transparent electrode through the opening, so as to connect the first p transparent electrode with the second p transparent electrode and connect the first p transparent electrode with the third p transparent electrode, wherein 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 toward the outside through the third LED stack.

10. The light emitting diode stack for a display according to claim 9, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. The second bonding layer and the third bonding layer transmit light generated from the first LED stack and the second LED stack.

11. The light emitting diode stack for a display according to claim 10, wherein: Light generated from the first LED stack is emitted to the outside through the first p-transparent electrode, the second p-transparent electrode, and the third p-transparent electrode. Light generated from the second LED stack is emitted to the outside through the second p transparent electrode and the third p transparent electrode.

12. The light emitting diode stack for a display according to claim 11, further comprising: The second n transparent electrode is located between the second bonding layer and the second LED stack and is in ohmic contact with the n-type semiconductor layer of the second LED stack.

13. The light emitting diode stack for a display according to claim 9, wherein: The first LED stack, the second LED stack, and the third LED stack emit red light, green light, and blue light, respectively.

14. The light emitting diode stack for a display according to claim 9, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. The first color filter and the second color filter are respectively low-pass filters, band-pass filters or band-stop filters.

15. The light emitting diode stack for a display according to claim 14, wherein: The first color filter and the second color filter are both distributed Bragg reflectors.

16. A display device comprising a plurality of pixels arranged on a supporting substrate, wherein: Each pixel includes the light emitting diode stack for a display as claimed in claim 1 .

17. The display device according to claim 16, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. The first color filter and the second color filter are respectively low-pass filters, band-pass filters or band-stop filters.

18. The display device according to claim 17, wherein: The p-type semiconductor layers of the first LED stack, the second LED stack, and the third LED stack of each pixel are electrically connected to a common line, and the n-type semiconductor layers are electrically connected to lines different from each other.

19. The display device according to claim 18, wherein: The common lines are data lines and the different lines are scan lines.

20. The display device according to claim 19, wherein: The lower insulating layer includes a distributed Bragg reflector that reflects red light, green light, and blue light.

21. The display device according to claim 19, in, The first p reflective electrode adjacent to the first LED stack is continuously disposed across a plurality of pixels so as to be applied as a common line.

22. The display device according to claim 16, wherein: The first p reflective electrode is limitedly disposed in each pixel region.

23. The display device according to claim 16, wherein: The first color filter transmits light generated from the first LED stack and reflects light generated from the second LED stack, The second color filter transmits light generated from the first LED stack and the second LED stack and reflects light generated from the third LED stack. the second bonding layer transmits light generated from the first LED stack, The third bonding layer transmits light generated from the first LED stack and the second LED stack.

24. The display device according to claim 23, wherein: The first bonding layer, the second bonding layer and the third bonding layer are transparent inorganic insulating films, transparent organic insulating films or transparent conductive films.

25. The display device according to claim 16, wherein: The third LED stack includes a surface region where an upper surface is rough.

26. The display device according to claim 16, wherein: The first LED stack, the second LED stack, and the third LED stack of each pixel can be driven independently.

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