Systems and methods for multi-color LED pixel units

Abstract

A miniature multicolor LED device includes two or more LED structures for emitting a series of colors of light. The two or more LED structures are vertically stacked to mix the light emitted by the two or more LED structures vertically and / or horizontally, and to reflect it upwards via some reflective structures. In some embodiments, each LED structure is connected to a pixel driver and / or a common electrode. The LED structures are bonded together by a bonding layer. In some embodiments, a planarization layer encloses each LED structure or miniature multicolor LED device. In some embodiments, one or more of a reflective layer, a refractive layer, a microlens, a spacer, and a reflector cup structure are implemented in the device to improve the luminous efficiency of the LEDs. A display panel including an array of miniature tricolor LED devices has high resolution and high illumination brightness.

Description

[0001] Cross-references to related applications

[0002] This application claims U.S. Provisional Patent Application No. 62 / 863,559, filed June 19, 2019, entitled "Systems and Methods for Coaxial Multi-Color LED"; U.S. Provisional Patent Application No. 63 / 013,358, filed April 21, 2020, entitled "Light-Emitting Diode Chip Structures with Reflective Elements"; U.S. Provisional Patent Application No. 63 / 013,370, filed April 21, 2020, entitled "Light-Emitting Diode Chip Structures with Reflective Elements"; and U.S. Provisional Patent Application No. 63 / 034,391, filed June 3, 2020, entitled "Systems and Methods for Multi-Color LED Pixel Unit with Vertical Priority is claimed in U.S. Provisional Patent Application No. 63 / 034,394, filed June 3, 2020, entitled "Systems and Methods for Multi-Color LED Pixel Unit with Horizontal Light Emission", each of which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to light-emitting diode (LED) display devices, and more specifically, to systems and methods of manufacturing LED semiconductor devices that emit different colors of light having high brightness and micron-sized pixels. Background Technology

[0004] With the development of mini-LED and micro-LED technologies in recent years, consumer devices and applications such as augmented reality (AR), virtual reality (VR), projection, head-up displays (HUDs), mobile device displays, wearable device displays, and automotive displays require LED panels with improved resolution and brightness. For example, an AR display integrated into goggles and positioned close to the wearer's eyes can be as small as a fingernail while still requiring HD (1280x720 pixels) or higher resolution. Many electronic devices require a certain pixel size, a certain distance between adjacent pixels, a certain brightness, and a certain viewing angle for the LED panel. Often, maintaining both resolution and brightness requirements simultaneously is challenging when attempting to achieve maximum resolution and brightness on a small display. Conversely, in some cases, pixel size and brightness are difficult to balance simultaneously because they have roughly opposite relationships. For example, achieving high brightness per pixel results in low resolution. Or, achieving high resolution results in decreased brightness.

[0005] Typically, at least red, green, and blue are superimposed to reproduce a wide range of colors. In some cases, to include at least red, green, and blue within a pixel area, individual monochrome LEDs are fabricated on different non-overlapping regions within the pixel area. Existing technologies face the challenge of increasing the effective illumination area within each pixel when the distance between adjacent LEDs is fixed. On the other hand, further improving the overall resolution of an LED panel becomes a difficult task when the illumination area of ​​a single LED is fixed, because LEDs of different colors must occupy their designated areas within a single pixel.

[0006] The combination of active-matrix liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays with thin-film transistor (TFT) technology is becoming increasingly popular in today's commercial electronic devices. These displays are widely used in personal laptops, smartphones, and personal digital assistants. Millions of pixels work together to create images on the display. TFTs act as switches to individually turn each pixel on and off, making the pixel bright or dark, allowing for convenient and efficient control of each pixel and the entire display.

[0007] However, traditional LCD displays suffer from low light efficiency, resulting in high power consumption and limited battery life. While active-matrix organic light-emitting diode (AMOLED) display panels typically consume less power than LCD panels, they remain a major power consumer in battery-powered devices. To extend battery life, it is necessary to reduce the power consumption of the display panel.

[0008] Traditional inorganic semiconductor light-emitting diodes (LEDs) have demonstrated excellent luminous efficiency, making active matrix LED displays more desirable for battery-powered devices. Driver circuits and LED arrays are used to control millions of pixels to display images on the screen. Both monochrome and full-color display panels can be manufactured using various methods.

[0009] However, integrating thousands or even millions of microLEDs with pixel driving circuit arrays is challenging. Various manufacturing methods have been proposed. In one method, the control circuitry is fabricated on a single substrate, and the LEDs are fabricated on separate substrates. The LEDs are transferred to an intermediate substrate, and the original substrate is removed. The LEDs on the intermediate substrate are then picked up, and one or more are sequentially placed onto a substrate containing the control circuitry. However, this manufacturing process is inefficient, expensive, and unreliable. Furthermore, there are no readily available production tools for the large-scale transfer of microLEDs. Therefore, new tools must be developed.

[0010] In another approach, the entire LED array with the original substrate is aligned with the control circuit and bonded to it using metal bonding. The substrate with the LEDs is retained in the final product, which can lead to optical crosstalk. Additionally, thermal mismatch between the two different substrates creates stress at the bonding interface, potentially causing reliability issues. Furthermore, multicolor display panels typically require more LEDs and different colors of LEDs grown on different substrate materials compared to monochrome display panels, making traditional manufacturing processes more complex and inefficient.

[0011] Display technology is becoming increasingly popular in today's commercial electronic devices. These display panels are widely used in fixed large screens such as LCD TVs and OLED TVs, as well as in portable electronic devices such as personal laptops, smartphones, tablets, and wearable devices. The development direction of fixed large screen technology is to achieve wide viewing angles to accommodate and enable multiple viewers to see the screen from various angles. For example, various liquid crystal materials such as super-twisted nematic (STN) and thin-film compensated super-twisted nematic (FSTN) have been developed to achieve wide viewing angles for all pixel light sources in the display panel.

[0012] However, most portable electronic devices are designed primarily for a single user, and the screen orientation of these devices should be adjusted to provide the optimal viewing angle for the individual user, rather than a wide viewing angle to accommodate multiple viewers. For example, the appropriate viewing angle for a user could be perpendicular to the screen surface. In this case, most of the light emitted at a wide viewing angle is wasted compared to a fixed large screen. Furthermore, a wide viewing angle raises privacy concerns when using portable electronic devices in public areas.

[0013] Furthermore, in conventional projection systems based on passive imaging devices such as liquid crystal displays (LCDs), digital mirror devices (DMDs), and liquid crystal on silicon (LCOS), the passive imaging devices themselves do not emit light. Specifically, conventional projection systems project an image by optically modulating a portion of the parallel light emitted from a light source—for example, a portion emitted at the pixel level by an LCD panel or reflected at the pixel level by a DMD panel. However, the portion of light that is not emitted or reflected is lost, reducing the efficiency of the projection system. Moreover, to provide parallel light, complex illumination optics are required to collect the diverging light emitted by the light source. These illumination optics not only make the system bulky but also introduce additional light loss into the system, further impacting its performance. In conventional projection systems, typically less than 10% of the illumination light generated by the light source is used to form the projected image.

[0014] Light-emitting diodes (LEDs), made of semiconductor materials, can be used in monochrome or full-color displays. In current displays employing LEDs, LEDs are typically used as a light source to provide light that is optically modulated by, for example, an LCD or DMD panel. That is, the light emitted by the LED itself does not form an image. LED displays that include LED panels comprising multiple LED dies as imaging devices have also been studied. In such LED displays, the LED panel is a self-emitting imaging device, where each pixel may include one LED die (monochrome display) or multiple LED dies, each die representing a primary color (full-color display).

[0015] However, the light emitted by an LED chip is spontaneously emitted and therefore non-directional, resulting in a large divergence angle. A large divergence angle can cause various problems for micro-LED displays. On the one hand, due to the large divergence angle, only a small portion of the light emitted by a micro-LED can be utilized. This significantly reduces the efficiency and brightness of the micro-LED display system. On the other hand, due to the large divergence angle, the light emitted by one micro-LED pixel can illuminate its adjacent pixels, causing inter-pixel crosstalk, loss of sharpness, and loss of contrast. Traditional solutions to reduce the large divergence angle may not effectively handle the overall light emitted by a micro-LED, utilizing only the central portion of the emitted light, leaving the remaining portion, emitted at a more oblique angle, unused.

[0016] In summary, there is a need to provide an LED structure for display panels that addresses, in particular, the aforementioned drawbacks and other defects. Summary of the Invention

[0017] There is a need to improve the design of multi-color LEDs, which would improve upon and help address the aforementioned shortcomings of conventional display systems. In particular, there is a need for LED device structures that can simultaneously improve brightness and resolution while effectively maintaining low power consumption. Furthermore, there is a need for display panels that reduce viewing angles to better protect user privacy and / or reduce light waste to lower power consumption, as well as reduce light interference between pixels to provide a better image.

[0018] The multicolor LED device described herein integrates at least three micro-LED structures arranged in different layers to form a vertically stacked device structure, and utilizes individual electrodes to receive control current. By arranging at least three LED structures aligned along the same axis as disclosed herein, the system effectively improves the light illumination efficiency within a single pixel area while simultaneously increasing the resolution of the LED panel.

[0019] Pitch refers to the distance between the centers of adjacent pixels on a display panel. In some embodiments, the pitch can vary from about 40 micrometers to about 20 micrometers, about 10 micrometers, and / or preferably about 5 micrometers or less. Many efforts have been made to reduce the pitch. Once the pitch size is determined, the area of ​​a single pixel is fixed.

[0020] The multicolor coaxial LED system described in this paper enables the emission of light mixed with different colors from a single pixel region without using additional areas to accommodate LED structures with different colors. Therefore, the footprint of a single pixel is significantly reduced, and the resolution of the micro-LED panel can be improved. Simultaneously, the concentration of different colors of light at the boundary of a micro-LED device greatly enhances the brightness within a single pixel region.

[0021] Compared to conventional manufacturing processes for micro-LED display chips that rely on inefficient pick-and-place processes or unreliable multi-substrate methods, the multi-color micro-LED manufacturing process disclosed herein effectively improves the efficiency and reliability of micro-LED device fabrication. For example, the LED structure can be directly bonded to a substrate with pixel drivers without the introduction of intermediate substrates, simplifying the manufacturing process and thus improving the reliability and performance of the LED chip. Furthermore, no substrate for the micro-LED structure is retained in the final multi-color device, thereby reducing crosstalk and mismatch. Additionally, planarization is applied to each LED structure within the multi-color micro-LED or to the entire multi-color micro-LED, allowing different LED structures and / or other layers to be directly bonded or formed together within the planarization layer with minimal disruption to the existing structure.

[0022] The multicolor microLED devices described herein may include vertical emission and horizontal emission, or any combination thereof. Vertical emission refers to light emitted, for example, from stacked individual LED structures, generally vertically relative to the surface of a substrate. Horizontal emission refers to light emitted, for example, from stacked individual LED structures, generally horizontally relative to the surface of a substrate and then reflected, generally vertically, by some reflective structures. Since vertically emitted light needs to pass through all the different layers within the multicolor microLED device, improved light propagation and reflection at each layer are achieved. Compared to vertical emission, horizontally emitted light from stacked individual LED structures does not need to pass through all the layers above a particular structure. Therefore, horizontal emission can have better light propagation efficiency and produce better light saliency.

[0023] Various embodiments include display panels with integrated microlens arrays. The display panel typically includes an array of pixel light sources (e.g., LED, OLED) electrically coupled to corresponding pixel driving circuitry (e.g., FET). The microlens array is aligned with the pixel light sources and reduces the divergence of light generated by the pixel light sources. The display panel may also include integrated optical spacers to maintain gaps between the microlenses and the pixel driving circuitry.

[0024] Microlens arrays reduce the divergence angle of light generated by pixel light sources and the usable viewing angle of the display panel. This, in turn, reduces power waste, increases brightness, and / or better protects user privacy in public areas.

[0025] Display panels integrating microlens arrays can be manufactured using various production methods, resulting in a wide range of device designs. In one approach, the microlens array is directly fabricated as a protrusion or mesa of a substrate with pixel light sources. In other approaches, techniques such as self-assembly, high-temperature reflow, grayscale photolithography, molding / imprinting / stamping, and dry etching pattern transfer can be used to fabricate microlens arrays.

[0026] Other aspects include components, devices, systems, improvements, methods and processes including manufacturing methods, applications, and other technologies related to any of the above aspects.

[0027] Some exemplary embodiments include a reflector disposed on a semiconductor substrate and surrounding a light-emitting region, such as an area from which light is emitted from a multicolor microLED device. The reflector reduces the divergence of light emitted from the light-emitting region and suppresses optical crosstalk between adjacent pixel units. For example, the reflector can utilize light at an angle, which is more efficient in collecting and converging the light to achieve a display with higher brightness and higher power efficiency than conventional solutions. Additionally, the reflector can block light emitted by microLEDs in adjacent pixel units, which can effectively suppress inter-pixel optical crosstalk and improve color contrast and sharpness. Exemplary embodiments of this disclosure can improve projection brightness and contrast, thus reducing power consumption in projection applications. Exemplary embodiments of this disclosure also improve the directionality of light emission from the display, thus providing users with better image quality and protecting user privacy in direct-view applications. Exemplary embodiments of this disclosure can provide several advantages. One advantage is that exemplary embodiments of this disclosure can suppress inter-pixel optical crosstalk and improve brightness. Exemplary embodiments of this disclosure can suppress inter-pixel optical crosstalk at smaller pitches while improving brightness within a single pixel in a power-efficient manner.

[0028] In some exemplary embodiments, a single-pixel multicolor LED device may include one or more top electrodes integrated with a reflector. The top electrodes may be electrically connected to a top electrode layer. The top electrodes integrated with the reflector allow for a more compact structure of the single-pixel multicolor LED device and simplify the manufacturing process. By employing top electrodes, the reflector can serve as a common P-electrode or N-electrode for the single-pixel multicolor LED device, and thus can provide a compact structure for the single-pixel multicolor LED device.

[0029] In some exemplary embodiments, in addition to the reflector, the microLED pixel unit may also include a microlens. The microlens can be aligned with the light-emitting area and reduce the divergence of light emitted by the light source, thereby reducing the usable viewing angle of the single-pixel multicolor LED device. For example, the microlens may be coaxially aligned with the light-emitting area and positioned on the light-emitting area and on top of the reflector. A portion of the light emitted by the light-emitting area can directly reach and pass through the microlens; another portion can reach and be reflected by the reflector, then reach and pass through the microlens. Therefore, light divergence can be reduced, and the usable viewing angle can be reduced to a level that allows a display and panel using the single-pixel multicolor LED device to be seen by a user perpendicular to the surface of the display and panel. In turn, power waste can be reduced and brightness increased, and / or user privacy can be better protected in public areas. In another example, the microlens may be coaxially aligned with the light-emitting area, located on the light-emitting area, and surrounded by the reflector. A portion of the light emitted from the light-emitting area reaches and passes directly through the microlens; another portion reaches the reflector, is reflected, and then reaches and passes through the microlens; the remaining light reaches and is reflected without passing through the microlens. Therefore, divergence can be reduced, and the usable viewing angle can be reduced to a level that allows several users to see the display and panel using this single-pixel multicolor LED device. This also reduces power waste, increases brightness, and / or properly protects user privacy in public areas.

[0030] In some exemplary embodiments, the single-pixel multicolor LED device may further include spacers. The spacers may be optically transparent layers formed to provide appropriate spacing between the microlens and the light-emitting region. For example, when the microlens is positioned above a reflector, the spacers may be positioned between the top of the microlens and the reflector. Thus, light emitted from the light-emitting region can pass through the spacers and then through the microlens. The spacers may also fill the area surrounded by the reflector to increase the refractive index of the medium surrounding the light-emitting region. Therefore, the spacers can alter the optical path of the light emitted from the light-emitting region. By employing microlenses, the light extraction efficiency of the single-pixel multicolor LED device can be improved, further enhancing the brightness of, for example, a microLED display panel.

[0031] In some exemplary embodiments, a single-pixel multicolor LED device may include a stepped reflector. The stepped reflector may include a cavity surrounding a light-emitting region. This cavity may be formed from multiple inclined surfaces surrounding the light-emitting region. Sub-cavities may be formed from multiple inclined surfaces and may have different dimensions in the horizontal direction. The stepped reflector may be disposed on a semiconductor substrate. The stepped reflector can reduce the divergence of light emitted from the light-emitting region and suppress optical crosstalk between adjacent pixel units. For example, the stepped reflector can utilize light at an inclined angle by reflecting light along different reflection directions. Furthermore, the stepped reflector can block light emitted from micro-LEDs in adjacent pixel units, which effectively suppresses optical crosstalk between pixels and improves color contrast and sharpness. Exemplary embodiments of this disclosure can improve projection brightness and contrast, and thus reduce power consumption in projection applications. Exemplary embodiments of this disclosure can also improve the directionality of light emission from the display, and thus provide users with better image quality and protect user privacy in direct-view applications.

[0032] The multicolor micro-LED devices described in this article can simultaneously improve brightness and resolution and are suitable for current display panels, especially for high-definition AR devices and virtual reality (VR) glasses.

[0033] Some exemplary embodiments provide a multicolor micro light-emitting diode (LED) pixel unit for a display panel, comprising: a first color LED structure formed on an IC substrate, wherein the first color LED structure includes a first light-emitting layer and a first reflective structure is formed at the bottom of the first light-emitting layer; a first dielectric bonding layer having a planar top surface and covering the first color LED structure; a second color LED structure formed on the planar top surface of the first dielectric bonding layer, wherein the second color LED structure includes a second light-emitting layer and a second reflective structure is formed at the bottom of the second light-emitting layer; a second dielectric bonding layer having a planar top surface and covering the second color LED structure; a top electrode layer covering the micro LED pixel unit and electrically contacting the first color LED structure and the second color LED structure; and an IC substrate electrically connected to the first color LED structure and the second LED structure.

[0034] Some exemplary embodiments provide a micro LED pixel unit, comprising: a first color LED structure formed on an IC substrate, wherein the first color LED structure includes a first light-emitting layer and a first reflective structure is formed on the bottom of the first light-emitting layer; a first dielectric bonding layer having a planar top surface and covering the first color LED structure; a second color LED structure formed on the planar top surface of the first dielectric bonding layer, wherein the second color LED structure includes a second light-emitting layer and a second reflective structure is formed on the bottom of the second light-emitting layer; a second dielectric bonding layer having a planar top surface and covering the second color LED structure; a third color LED structure formed on the top surface of the second dielectric bonding layer, wherein the third color LED structure includes a third light-emitting layer and a third reflective structure is formed on the bottom of the third light-emitting layer; a third dielectric bonding layer having a planar top surface and covering the third color LED structure; a top electrode layer covering the micro LED pixel unit and electrically contacting the first color LED structure, the second color LED structure, and the third color LED structure; and an IC substrate electrically connected to the first color LED structure, the second color LED structure, and the third color LED structure.

[0035] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first dielectric bonding layer is transparent and the second dielectric bonding layer is transparent.

[0036] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first reflective structure includes at least one first high reflectivity layer, the second reflective structure includes at least one second high reflectivity layer, and the third reflective structure includes at least one third high reflectivity layer; the reflectivity of the first high reflectivity layer, the second high reflectivity layer, or the third high reflectivity layer is greater than 60%.

[0037] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the material of the first high reflectivity layer, the second high reflectivity layer or the third high reflectivity layer is one or more metals selected from Rh, Al, Ag and Au.

[0038] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure includes at least two first high reflectivity layers with different refractive indices; the second reflective structure includes at least two second high reflectivity layers with different refractive indices; and the third reflective structure includes at least two third high reflectivity layers with different refractive indices.

[0039] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure further includes a first transparent layer on a first high reflectivity layer; the second reflective structure further includes a second transparent layer on a second high reflectivity layer; and the third reflective structure further includes a second transparent layer on a third high reflectivity layer.

[0040] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first transparent layer is selected from one or more of ITO and SiO2; the second transparent layer is selected from one or more of ITO and SiO2; and the third transparent layer is selected from one or more of ITO and SiO2.

[0041] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure further includes a first bottom electrode conductive contact layer, the second color LED structure further includes a second bottom electrode conductive contact layer, and the third color LED structure further includes a third bottom electrode conductive contact layer; the first bottom electrode conductive contact layer is electrically connected to the IC substrate through a first contact via at the bottom of the first bottom electrode conductive contact layer; the second bottom electrode conductive contact layer is electrically connected to the IC substrate through a second contact via passing through the first dielectric bonding layer; and the third bottom electrode conductive contact layer is electrically connected to the IC substrate through a third contact via passing through the second dielectric layer and the first dielectric bonding layer.

[0042] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first bottom electrode conductive contact layer is transparent, the second bottom electrode conductive contact layer is transparent, and the third bottom electrode conductive contact layer is transparent.

[0043] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a first extension portion extends from one side of the first light-emitting layer; a second extension portion extends from one side of the second light-emitting layer; a third extension portion extends from one side of the second light-emitting layer; and a top contact via passes through the second dielectric bonding layer and the third dielectric bonding layer to connect the first extension portion, the second extension portion and the third extension portion to the top electrode layer.

[0044] Some exemplary embodiments provide a micro LED pixel unit, including at least: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; and a reflective optical isolation structure formed around the light-emitting region, wherein the top of the reflective optical isolation structure is higher than the top of the light-emitting region.

[0045] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the microlens is located on top of the light-emitting area.

[0046] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the top of the reflective optical isolation structure is higher than the top of the microlens.

[0047] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the reflective optical isolation structure has a top opening, and the lateral area of ​​the microlens is smaller than the lateral area of ​​the top opening.

[0048] In some exemplary embodiments of the micro-LED pixel unit or any combination of the aforementioned exemplary embodiments, the lateral dimension of the microlens is larger than the effective light-emitting area of ​​the first color LED structure; the lateral dimension of the microlens is larger than the effective light-emitting area of ​​the second color LED structure; and the lateral dimension of the microlens is larger than the effective light-emitting area of ​​the third color LED structure.

[0049] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the lateral dimensions of the first color LED structure, the second color LED structure, and the third color LED structure are the same.

[0050] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure have the same central axis.

[0051] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first dielectric bonding layer is transparent, the second dielectric bonding layer is transparent, and the third dielectric bonding layer is transparent.

[0052] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the thickness of the first reflective structure is 5 nm to 10 nm; the thickness of the second reflective structure is 5 nm to 10 nm; the thickness of the third reflective structure is 5 nm to 10 nm; the thickness of the first LED structure is no more than 300 nm; the thickness of the second LED structure is no more than 300 nm; and the thickness of the third LED structure is no more than 300 nm.

[0053] Some exemplary embodiments provide a multicolor micro-LED pixel unit for a display panel, comprising: a first LED structure formed on an IC substrate that emits a first color light; a first transparent dielectric bonding layer having a first planar top surface and covering the first LED structure; a second LED structure formed on the first planar top surface of the first transparent dielectric bonding layer that emits a second color light; a second transparent dielectric bonding layer having a second planar top surface and covering the second LED structure; and a top electrode layer covering the multicolor micro-LED pixel unit and electrically contacting the first LED structure and the second LED structure; wherein the IC substrate is electrically connected to the first LED structure and the second LED structure.

[0054] Some exemplary embodiments provide a micro LED pixel unit, including: a first color LED structure formed on an IC substrate; a first transparent dielectric bonding layer having a planar top surface and covering the first color LED structure; a second color LED structure formed on the planar top surface of the first transparent dielectric bonding layer; a second transparent dielectric bonding layer having a planar top surface and covering the second color LED structure; a third color LED structure formed on the planar top surface of the second transparent dielectric bonding layer; a third dielectric bonding layer having a planar top surface and covering the third color LED structure; a top electrode layer covering the micro LED pixel unit and electrically contacting the first color LED structure, the second color LED structure, and the third color LED structure; and an IC substrate electrically connected to the first color LED structure, the second LED structure, and the third LED structure.

[0055] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a first reflective structure is formed at the bottom of the first color LED structure; a second reflective structure is formed at the bottom of the second color LED structure; and a third reflective structure is formed at the bottom of the third color LED structure.

[0056] Some exemplary embodiments provide a micro LED pixel unit, comprising: an IC substrate; a light-emitting region formed on the IC substrate and including at least one LED structure and at least one dielectric bonding layer, wherein each dielectric bonding layer has a planar top surface covering the surface of each LED structure; a top electrode layer covering the micro LED pixel unit and electrically connected to each color LED structure, wherein the IC substrate is electrically connected to each color LED structure; and a stepped reflector cup structure having a cavity and surrounding the light-emitting region.

[0057] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; a reflective optical isolation structure formed around the light-emitting region; and a refractive structure formed between the reflective optical isolation structure and the light-emitting region.

[0058] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, the light-emitting region including at least one LED structure and at least one transparent dielectric bonding layer, wherein each transparent dielectric bonding layer has a planar top surface covering the surface of each LED structure; a top electrode layer covering the micro LED pixel unit and electrically contacting each color LED structure, wherein an IC substrate is electrically connected to each color LED structure; a stepped reflector structure formed around the light-emitting region; and a refractive structure formed between the stepped reflector structure and the light-emitting region.

[0059] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflector cup structure has a top opening, and the lateral area of ​​the microlens is smaller than the lateral area of ​​the top opening.

[0060] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; and a floating reflective optical isolation structure surrounding the light-emitting region, wherein the floating reflective optical isolation structure is positioned at a certain distance above the semiconductor substrate.

[0061] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; a reflective optical isolation structure surrounding the light-emitting region; and a top electrode layer covering the light-emitting region and electrically connected to the reflective optical isolation structure, wherein the top electrode layer is in electrical contact with the reflective optical isolation structure.

[0062] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the edge of the top electrode layer touches the reflective optical isolation structure.

[0063] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the light-emitting region includes: at least one LED structure and at least one dielectric bonding layer; a top electrode layer covering the micro LED pixel unit and in electrical contact with each color LED structure, wherein a semiconductor substrate is electrically connected to each color LED structure.

[0064] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective optical isolation structure is a floating reflective structure.

[0065] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the reflective optical isolation structure is a stepped reflector cup structure.

[0066] Some exemplary embodiments provide a micro LED pixel unit, comprising at least: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; a floating reflective optical isolation structure surrounding the light-emitting region, wherein the floating reflective optical isolation structure is located at a certain distance above the semiconductor substrate; and a top electrode layer formed on top of the light-emitting region, wherein the top electrode layer is in contact with the floating reflective optical isolation structure.

[0067] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the light-emitting region includes at least one LED structure and a bonding layer located at the bottom of each LED structure.

[0068] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first color LED structure further includes a first bottom electrode conductive contact layer, and the second color LED structure further includes a second bottom electrode conductive contact layer; the first bottom electrode conductive contact layer is electrically connected to the IC substrate through a first contact via located at the bottom of the first bottom electrode conductive contact layer; the second bottom electrode conductive contact layer is electrically connected to the IC substrate through a second contact via passing through the first dielectric bonding layer.

[0069] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate; a top electrode layer covering the light-emitting region and in electrical contact with the light-emitting region; a reflector structure formed around the light-emitting region, wherein the top electrode layer is electrically connected to the reflector structure, the semiconductor substrate is electrically connected to the reflector structure; and a refractive structure formed between the reflector structure and the light-emitting region.

[0070] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, the light-emitting region including at least one LED structure and a bonding layer located at the bottom of each LED structure, wherein each LED structure includes a light-emitting layer and a bottom reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering the micro LED pixel unit and electrically contacting each color LED structure, wherein the semiconductor substrate is electrically connected to each color LED structure; a reflector structure formed around the light-emitting region; and a refractive structure formed between the reflector structure and the light-emitting region.

[0071] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, the light-emitting region including at least one LED structure and a bonding layer located at the bottom of each LED structure, wherein the LED structure includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering the LED structure pixel unit and electrically contacting each color LED structure, wherein the semiconductor substrate is electrically connected to each color LED structure; and a stepped reflector structure surrounding the light-emitting region, wherein light emitted from the sidewalls of the first and second light-emitting layers along a horizontal plane reaches the stepped reflector structure and is reflected upward by the stepped reflector structure, wherein the top of the stepped reflector structure is higher than the top of the light-emitting region.

[0072] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, the light-emitting region including at least one LED structure and a metal bonding layer located at the bottom of each LED structure, wherein the LED structure includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering the micro LED pixel unit and electrically contacting each color LED structure, wherein the semiconductor substrate is electrically connected to each color LED structure; and a floating reflector structure surrounding the light-emitting region, wherein the floating reflector structure is positioned at a certain distance from the semiconductor substrate, and light emitted from the sidewalls of the first and second light-emitting layers along a horizontal plane reaches the floating reflector structure and is reflected upward by the floating reflector structure.

[0073] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the bottom of the floating reflector structure is higher than the top surface of the semiconductor substrate.

[0074] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the floating reflector structure is a stepped reflector structure.

[0075] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first LED structure is embedded within a first planarized transparent dielectric layer.

[0076] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first planarized transparent dielectric layer is composed of a solid inorganic material or a plastic material.

[0077] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the second LED structure is embedded within a second planarized transparent dielectric layer.

[0078] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the second planarized transparent dielectric layer is composed of a solid inorganic material or a plastic material.

[0079] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first transparent dielectric bonding layer is composed of a solid inorganic material or a plastic material.

[0080] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first LED structure includes a first bottom electrode conductive contact layer formed at the bottom of the first LED structure; the second LED structure includes a second bottom electrode conductive contact layer formed at the bottom of the second LED structure; the first bottom electrode conductive contact layer is electrically connected to the IC substrate through a first contact in a first via located at the bottom of the first bottom electrode conductive contact layer; and the second bottom electrode conductive contact layer is electrically connected to the IC substrate through a second contact in a second via passing through a first transparent dielectric bonding layer.

[0081] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first bottom electrode conductive contact layer is transparent, and the second bottom electrode conductive contact layer is transparent.

[0082] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first LED structure includes a first light-emitting layer; a first side extending from one side of the first light-emitting layer; the second LED structure includes a second light-emitting layer; a second side extending from one side of the second light-emitting layer; and a third contact in a third via through a second transparent dielectric bonding layer connecting the first side and the second side to a top electrode layer.

[0083] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the optical isolation structure is formed around the micro-LED pixel unit.

[0084] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the optical isolation structure is a reflector.

[0085] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the lateral dimension of the first LED structure is the same as the lateral dimension of the second LED structure.

[0086] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first LED structure and the second LED structure have the same central axis.

[0087] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a first reflective layer is formed at the bottom of the first LED structure; and a second reflective layer is formed at the bottom of the second LED structure.

[0088] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the thickness of the first reflective layer is 5 to 10 nm; the thickness of the second reflective layer is 5 to 10 nm; the thickness of the first LED structure is no greater than 300 nm; and the thickness of the second LED structure is no greater than 300 nm.

[0089] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a bonding metal layer is formed at the bottom of the first LED structure.

[0090] Some exemplary embodiments provide a miniature LED pixel unit, comprising: a first color LED structure formed on an IC substrate, wherein the first color LED structure includes a first light-emitting layer and a first reflective structure formed on the bottom of the first light-emitting layer; a first bonding metal layer formed on the bottom of the first color LED structure and configured to bond the IC substrate and the first color LED structure; a second bonding metal layer formed on top of the first color LED structure; a second color LED structure formed on the second bonding metal layer, wherein the second color LED structure includes a second light-emitting layer and a second reflective structure formed on the bottom of the second light-emitting layer; a top electrode layer covering the first color LED structure and the second color LED structure and in electrical contact with the first color LED structure and the second color LED structure, wherein the IC substrate is electrically connected to the first color LED structure and the second color LED structure; and a reflector cup surrounding the first color LED structure and the second color LED structure, wherein light emitted from the first light-emitting layer and the second light-emitting layer in a horizontal direction reaches the reflector cup and is reflected upward by the reflector cup.

[0091] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure includes at least one first reflective layer, the second reflective structure includes at least one second reflective layer, and the reflectivity of the first reflective layer or the second reflective layer is greater than 60%.

[0092] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the material of the first reflective layer or the second reflective layer includes one or more of Rh, Al, Ag or Au.

[0093] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure includes two first reflective layers with different refractive indices, and wherein the second reflective structure includes two second reflective layers with different refractive indices.

[0094] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the two first reflective layers comprise SiO2 and Ti3O5, respectively, and the two second reflective layers comprise SiO2 and Ti3O5, respectively.

[0095] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure further includes a first transparent layer on the first reflective layer, and the second reflective structure further includes a second transparent layer on the second reflective layer.

[0096] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first transparent layer comprises one or more of indium tin oxide (ITO) or SiO2, and the second transparent layer comprises one or more of ITO or SiO2.

[0097] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first color LED structure further includes a first bottom conductive contact layer and a first top conductive contact layer, and the second color LED structure further includes a second bottom conductive contact layer and a second top conductive contact layer; a first light-emitting layer is located between the first bottom conductive contact layer and the first top conductive contact layer, and a second light-emitting layer is located between the second bottom conductive contact layer and the second top conductive contact layer; the first bottom conductive contact layer is electrically connected to the IC substrate through a first contact via, passing through the first reflective structure and the first bonding metal layer, and the second bottom conductive contact layer is electrically connected to the IC substrate through a second contact via; and the edge of the first top conductive contact layer contacts the top electrode layer, and the top surface of the second top conductive contact layer contacts the top electrode layer.

[0098] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflector cup is made of metal.

[0099] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, a microlens is formed above the top electrode layer.

[0100] In some exemplary embodiments of the microLED pixel unit or any combination of the aforementioned exemplary embodiments, a spacer is formed between the microlens and the top electrode layer.

[0101] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the spacer material includes silicon oxide.

[0102] In some exemplary embodiments of the micro-LED pixel unit or any combination of the aforementioned exemplary embodiments, the lateral dimension of the microlens is greater than the lateral dimension of the effective light-emitting area of ​​the first LED structure; the lateral dimension of the microlens is greater than the lateral dimension of the effective light-emitting area of ​​the second LED structure.

[0103] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first color LED structure and the second color LED structure have the same lateral dimension.

[0104] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the first color LED structure and the second color LED structure have the same central axis.

[0105] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the thickness of at least one first reflective layer is in the range of 5 nm to 10 nm, and the thickness of at least one second reflective layer is in the range of 5 nm to 10 nm, wherein the thickness of the first color LED structure is not greater than 300 nm, and the thickness of the second color LED structure is not greater than 300 nm.

[0106] Some exemplary embodiments provide a micro LED pixel unit, including: an IC substrate; a light-emitting region formed on the IC substrate, including a plurality of color LED structures, the bottom of each of the plurality of color LED structures being connected to a corresponding bonding metal layer in the light-emitting region, wherein each of the plurality of color LED structures includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering each of the plurality of color LED structures and electrically contacting each of the plurality of color LED structures, wherein the IC substrate is electrically connected to each of the plurality of color LED structures; and a stepped reflector cup forming a cavity, around the light-emitting region, light emitted horizontally from the sidewalls of the light-emitting layer of each of the plurality of color LED structures reaches the reflector cup and is reflected upward by the reflector cup.

[0107] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the inner wall of the cavity includes a plurality of inclined surfaces.

[0108] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the angles of the plurality of tilted surfaces relative to the surface of the IC substrate decrease from the bottom of the cavity to the top of the cavity.

[0109] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the sub-cavities formed by multiple inclined surfaces have different dimensions in the horizontal direction.

[0110] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the inner walls of the sub-cavities are not arranged in the same plane.

[0111] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the height of each sub-cavity is different.

[0112] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the height of the sub-cavity located in the middle of the cavity is less than the height of the other sub-cavities.

[0113] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the height of the sub-cavity located at the top of the cavity is greater than the height of the sub-cavity located at the bottom of the cavity.

[0114] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the plurality of color LED structures also include a top color LED structure.

[0115] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the top of the cavity is higher than the top of the top color LED structure.

[0116] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the cavity includes a plurality of sub-cavities, and each of the plurality of color LED structures is located in a different sub-cavity within the plurality of sub-cavities.

[0117] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a transparent dielectric bonding layer covers at least one of the plurality of colored LED structures, wherein the transparent dielectric bonding layer comprises a solid inorganic material or a plastic material.

[0118] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the solid inorganic material includes one or more of SiO2, Al2O3, Si3N4, phosphate silicate glass (PSG), and borosilicate glass (BPSG).

[0119] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the plastic material includes one or more polymers of SU-8, PermiNex, benzocyclobutene (BCB), and spin-coated glass (SOG).

[0120] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, each of the plurality of color LED structures includes a bottom conductive contact layer and a top conductive contact layer, and a light-emitting layer is formed between the bottom conductive contact layer and the top conductive contact layer; wherein the bottom conductive contact layer is electrically connected to the IC substrate through a contact via through a reflective structure and a corresponding bonding metal layer, and the top surface of the top conductive contact layer of the top color LED structure contacts the top electrode layer, and the edge of the top conductive contact layer of the color LED structure below the top color LED structure contacts the top electrode layer.

[0121] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, an extension portion extends from one side of the light-emitting layer of the color LED structure below the top color LED structure, and a contact via connects the extension portion to the top electrode layer.

[0122] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the lateral dimension of the microlens is larger than the luminous size of each of the plurality of color LED structures.

[0123] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the plurality of colored LED structures have the same central axis.

[0124] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective structure includes a reflective layer with a thickness ranging from 5 nm to 10 nm, and the thickness of each of the plurality of color LED structures does not exceed 300 nm.

[0125] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the material of the top electrode layer is selected from the following materials: graphene, indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO).

[0126] Some exemplary embodiments provide a micro LED pixel unit, the micro LED pixel unit comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, including a plurality of color LED structures, the bottom of each of the plurality of color LED structures being connected to a corresponding bonding metal layer in the light-emitting region, wherein each of the plurality of color LED structures includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering each of the plurality of color LED structures and electrically contacting each of the plurality of color LED structures, wherein the semiconductor substrate is electrically connected to each of the plurality of color LED structures; a reflector surrounding the light-emitting region; and a refractive structure formed between the reflector and the light-emitting region.

[0127] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a microlens is formed on the top surface of the refractive structure.

[0128] In some exemplary embodiments of the microLED pixel unit or any combination of the aforementioned exemplary embodiments, the lateral dimension of the microlens is not less than the lateral dimension of the light-emitting area.

[0129] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the reflector cup has a top opening region, and the lateral dimension of the microlens is smaller than the lateral dimension of the top opening region.

[0130] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a bottom dielectric layer is formed between the bottom of the reflector cup and the semiconductor substrate.

[0131] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a top conductive layer is formed on the top of the light-emitting area, and the top conductive layer is electrically connected to the reflector.

[0132] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the top conductive layer is in direct contact with the top or bottom of the reflector.

[0133] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the top of the refractive structure is higher than the top of the reflector.

[0134] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the semiconductor substrate is an IC substrate.

[0135] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflector is a stepped reflector that forms a cavity surrounding the light-emitting area.

[0136] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the sub-cavities formed by multiple inclined surfaces have different dimensions in the horizontal direction.

[0137] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, each of the plurality of color LED structures includes a respective extension portion extending from one side of the respective color LED structure, and the respective extension portion is electrically connected to the top electrode layer via a respective first contact via, and the bottom of each of the plurality of color LED structures is electrically connected to the semiconductor substrate via a respective second contact via.

[0138] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, including a plurality of color LED structures, the bottom of each of the plurality of color LED structures being connected to a corresponding bonding metal layer in the light-emitting region, wherein each of the plurality of color LED structures includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering each of the plurality of color LED structures and electrically contacting each of the plurality of color LED structures, wherein the semiconductor substrate is electrically connected to each of the plurality of color LED structures; and a reflector cup surrounding the light-emitting region, light emitted horizontally from the sidewall of the light-emitting layer of each of the plurality of color LED structures reaching the reflector cup and being reflected upward by the reflector cup, the top of the reflector cup being higher than the top of the light-emitting region.

[0139] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a microlens is formed above the light-emitting area.

[0140] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the top of the reflector cup is higher than the top of the microlens.

[0141] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a refractive structure is formed at the bottom of the microlens, between the reflector cup and the light-emitting area.

[0142] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the bottom of the light-emitting region is electrically connected to the semiconductor substrate.

[0143] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting region formed on the semiconductor substrate, including a plurality of color LED structures, the bottom of each of the plurality of color LED structures being connected to a corresponding bonding metal layer in the light-emitting region, wherein each of the plurality of color LED structures includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer; a top electrode layer covering each of the plurality of color LED structures and electrically contacting each of the plurality of color LED structures, wherein the semiconductor substrate is electrically connected to each of the plurality of color LED structures; and a floating reflector cup surrounding the light-emitting region, wherein the bottom of the floating reflector cup is located above the semiconductor substrate, and light emitted horizontally from the sidewall of the light-emitting layer of each of the plurality of color LED structures reaches the suspended floating reflector cup and is reflected upward by the suspended floating reflector cup.

[0144] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the bottom of the floating reflector cup is higher than the top surface of the corresponding bonding metal layer at the bottom of one of the multiple color LED structures.

[0145] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the floating reflector is stepped.

[0146] In some exemplary embodiments of the microLED pixel unit or any combination of the foregoing exemplary embodiments, the top of the floating reflector cup is higher than the top of the microlens.

[0147] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a refractive structure is formed at the bottom of the microlens, between the floating reflector and the light-emitting area.

[0148] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the floating reflector has a top opening region, and the lateral dimension of the microlens is smaller than the lateral dimension of the top opening region.

[0149] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a bottom dielectric layer is formed between the floating reflector and the semiconductor substrate.

[0150] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the top electrode layer directly contacts the top or bottom of the floating reflector.

[0151] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, a stepped floating reflector forms a cavity surrounding the light-emitting area.

[0152] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the material of the floating reflector cup includes metal.

[0153] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective structure includes a reflective layer formed at the bottom of each of the plurality of color LED structures.

[0154] In some exemplary embodiments of the micro LED pixel unit or any combination of the aforementioned exemplary embodiments, the thickness of the reflective layer is in the range of 5 nm to 10 nm, and the thickness of each of the multiple color LED structures does not exceed 300 nm.

[0155] The compact design of the multicolor LED devices and systems disclosed herein utilizes the lateral overlap of light-emitting LED structures, thereby improving the luminous efficiency, resolution, and overall performance of the LED display system. Furthermore, the fabrication of the multicolor LED display system reliably and efficiently forms LED structural patterns without the use or retention of additional substrates. In some cases, the design of the display devices and systems disclosed herein significantly reduces the number of microlens fabrication steps and improves the efficiency of display panel structure formation by utilizing the consistency between the shape of the microlens material and the shape of the multicolor LED devices, allowing microlenses to be formed directly on top of the multicolor LED devices on the substrate. Reduced viewing angle and decreased light interference improve the luminous efficiency, resolution, and overall performance of the display system. Therefore, the realization of this multicolor LED display system meets the stringent display requirements for AR and VR, head-up displays, mobile device displays, wearable device displays, high-definition miniature projectors, and automotive displays compared to the use of conventional LEDs.

[0156] It should be noted that the various embodiments described above can be combined with any other embodiments described herein. The features and advantages described in the specification are not exhaustive; in particular, many additional features and advantages will be apparent to those skilled in the art from the drawings, specification, and claims. Furthermore, it should be noted that the language used in the specification is chosen primarily for readability and guidance purposes and is not intended to define or limit the subject matter of the invention. Attached Figure Description

[0157] To enable this disclosure to be understood in more detail, it can be described more specifically by referring to the features of various embodiments, some of which are illustrated in the accompanying drawings. However, these drawings only illustrate relevant features of this disclosure and should not be considered limiting, as the description may allow for other valid features.

[0158] Figure 1AThis is a top view of a single-pixel tri-color LED device 100 according to some embodiments.

[0159] Figure 1B A single-pixel tri-color LED device 100 according to some embodiments Figure 1A Cross-sectional view of the middle diagonal 102.

[0160] Figure 1C A single-pixel tri-color LED device 100 according to some embodiments Figure 1A Cross-sectional view at 150° diagonal.

[0161] Figure 2A A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A Cross-sectional view of the middle diagonal 102.

[0162] Figure 2B A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A Cross-sectional view at 150° diagonal.

[0163] Figure 3A A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A Cross-sectional view of the middle diagonal 102.

[0164] Figure 3B A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A Cross-sectional view at 150° diagonal.

[0165] Figure 4A This is a top view of a layered planarized single-pixel tri-color LED device 400 according to some embodiments.

[0166] Figure 4B It is a layered planarized single-pixel tri-color LED device 400 according to some embodiments. Figure 4A Cross-sectional view of the middle diagonal 402.

[0167] Figure 5 It is a single-pixel tri-color LED device 500 with a refractive structure according to some embodiments. Figure 1A Cross-sectional view of the middle diagonal 102.

[0168] Figure 6A It is a single-pixel tri-color LED device 600 with microlenses on a reflective structure according to some embodiments. Figure 1A Cross-sectional view of the middle diagonal 102.

[0169] Figure 6BIt is according to some embodiments a single-pixel tri-color LED device 600 having microlenses in a region formed by a reflective structure along its edge. Figure 1A Cross-sectional view of the middle diagonal 102.

[0170] Figure 6C This is a manufacturing method for a display panel that uses top-down pattern transfer to form an integrated microlens array, according to some embodiments.

[0171] Figure 6D This is a manufacturing method for a display panel that uses top-down pattern transfer to form an integrated microlens array, according to some embodiments.

[0172] Figure 7 According to some embodiments, the three single-pixel tri-color LED devices 710, 720, and 730 located on substrate 104 are along... Figure 1A Cross-sectional view 700 of the diagonal of 102.

[0173] Figure 8 It is along some embodiments of a single-pixel tri-color LED device 800 having a stepped reflector cup. Figure 4A A cross-sectional view of the diagonal of a material such as 402.

[0174] Figure 9 It is a single-pixel tri-color LED device 900 with a floating reflector according to some embodiments. Figure 4A A cross-sectional view of the diagonal of a material such as 402.

[0175] Figure 10A This is a circuit diagram of a 1000-matrix matrix of single-pixel tri-color LED devices according to some embodiments.

[0176] Figure 10B This is a circuit diagram of a 1000-matrix matrix of single-pixel tri-color LED devices according to some embodiments.

[0177] Figure 11 This is a top view of a micro LED display panel 1100 according to some embodiments.

[0178] As is common practice, the various features illustrated in the accompanying drawings may not be drawn to scale. Therefore, for clarity, the dimensions of the features may be arbitrarily expanded or reduced. Additionally, some drawings may not depict all parts of a given system, method, or apparatus. Finally, the same reference numerals may be used to denote similar features throughout the specification and drawings. Detailed Implementation

[0179] This document describes numerous details to provide a thorough understanding of the exemplary embodiments illustrated in the accompanying drawings. However, some embodiments may be practiced without these detailed descriptions, and the scope of the claims is limited only to those features and aspects specifically detailed in the claims. Furthermore, well-known methods, components, and materials have not been described exhaustively so as not to unnecessarily obscure relevant aspects of the embodiments described herein.

[0180] In some embodiments, a single-pixel multicolor LED device includes two or more LED structures. In some embodiments, each LED structure includes at least one LED light-emitting layer that emits light of different colors. When a single-pixel multicolor LED device contains two LED structures, it can emit light of two colors and a mixture of the two colors. When a single-pixel multicolor LED device contains three LED structures, it can emit light of three colors and a mixture of the three colors.

[0181] In some embodiments, light emitted from a single-pixel multicolor LED device is emitted from the sidewalls of each LED structure within the single-pixel multicolor LED device. In some embodiments, a reflective structure is provided around the single-pixel multicolor LED device to reflect the light emitted from the sidewalls of each LED structure upwards. In some embodiments, light emitted from a single-pixel multicolor LED device is emitted from the top surface of each LED structure within the single-pixel multicolor LED device. In some embodiments, the light emitted from a single-pixel multicolor LED device is a combination of the light emitted from the sidewalls and the top surface of each LED structure within the single-pixel multicolor LED device; for example, the light emitted from the sidewalls accounts for approximately 20% to 100% of the light emitted by the single-pixel multicolor LED device.

[0182] Figure 1A This is a top view of a single-pixel tri-color LED device 100 according to some embodiments.

[0183] Figure 1B It is the edge of a single pixel tri-color LED device 100 according to some embodiments Figure 1A Cross-sectional view of the middle diagonal 102.

[0184] Figure 1C It is the edge of a single pixel tri-color LED device 100 according to some embodiments Figure 1A Cross-sectional view at 150° diagonal.

[0185] Diagonals 102 and 150 each pass through the center of the individual pixel tri-color LED device 100. Diagonals 102 and 150 are orthogonal to each other. In some embodiments, the tri-color LED device 100 includes a substrate 104. For convenience, "upward" is used to indicate away from the substrate 104, "downward" indicates towards the substrate 104, and other directional terms such as top, bottom, above, below, directly below, and under are also interpreted accordingly. The support substrate 104 is a substrate on which an array of various driving circuits 106 are fabricated. In some embodiments, the driving circuits may also be located on one of the layers above the substrate 104, or above the micro tri-color LED structure 100. Each driving circuit is a pixel driver 106. In some cases, the driving circuit 106 is a thin-film transistor pixel driver or a silicon CMOS pixel driver. In one embodiment, the substrate 104 is a Si substrate. In another embodiment, the support substrate 104 is a transparent substrate, such as a glass substrate. Examples of other substrates include GaAs, GaP, InP, SiC, ZnO, and sapphire substrates. The driving circuit 106 forms individual pixel drivers to control the operation of each individual pixel tri-color LED device 100. The circuitry on the substrate 104 includes contacts for each individual driving circuit 106 and ground contacts. Figure 1A , 1B As shown in 1C, each miniature tricolor LED structure 100 also has two types of contacts: a P electrode or anode connected to the pixel driver 106, such as 108, 126, 152; and an N electrode or cathode connected to ground (i.e., the common electrode), such as 116, 120, and 140.

[0186] In some embodiments, the N-electrode (or N-electrode contact pad) and its connecting components, such as 116, 120, and 140, are made of materials such as graphene, ITO, aluminum-doped zinc oxide (AZO), or fluorine-doped tin oxide (FTO), or any combination thereof. In some embodiments, the N-electrode (or N-electrode contact pad) and its connecting components, such as 116, 120, and 140, are made of a non-transparent or transparent conductive material, and in a preferred embodiment, are made of a transparent conductive material. In some embodiments, the P-electrode (or P-electrode contact pad) and its connecting components, such as 126 and 152, are made of materials such as graphene, ITO, AZO, or FTO, or any combination thereof. In some embodiments, the P-electrode (or P-electrode contact pad) and its connecting components, such as 126 and 152, are made of a non-transparent or transparent conductive material, and in a preferred embodiment, are made of a transparent conductive material. In some embodiments, the positions of the P-electrode (or P-electrode contact pad) and its connecting components and the N-electrode (or N-electrode contact pad) and its connecting components can be switched.

[0187] Although this article uses the term "layer" to describe some features, it should be understood that these features are not limited to a single layer, but can include multiple sub-layers. In some cases, a "structure" can take the form of "layers".

[0188] In some embodiments, the three LED structures, including LED light-emitting layers 112, 130 and 136 respectively, are stacked. For example, a green LED light-emitting layer 130 is formed on top of the red LED light-emitting layer 112, and a blue LED light-emitting layer 136 is formed on top of the green LED light-emitting layer 130.

[0189] Typically, an LED light-emitting layer includes a PN junction having p-type regions / layers and n-type regions / layers, and an active layer between the p-type regions / layers and the n-type regions / layers.

[0190] In some embodiments, such as Figure 1A and 1B As shown, the area of ​​the bottom red LED light-emitting layer 112 is larger than the area of ​​the middle green LED light-emitting layer 130. In some embodiments, the area of ​​the middle green LED light-emitting layer 130 is larger than the area of ​​the top blue LED light-emitting layer 136.

[0191] In some embodiments, the light emitted by the red LED light-emitting layer 112 can propagate horizontally toward the sidewall of the red LED light-emitting layer 112, and then be reflected upward by reflective elements such as 146 and / or 148 as described below, and emitted at the top surface of the single pixel tri-color LED device 100. As described below, a reflective layer 109 is provided below the red LED light-emitting layer 112, and a reflective layer 115 is provided above the red LED light-emitting layer 112. The light emitted by the red LED light-emitting layer 112 is reflected toward the sidewall of the red LED light-emitting layer 112 between the two reflective layers 109 and 115.

[0192] In some embodiments, light emitted from the green LED light-emitting layer 130 can propagate horizontally toward the sidewalls of the green LED light-emitting layer 130, and then be reflected upwards by reflective elements such as 146 and / or 148 as described below, and emitted at the top surface of the single-pixel tri-color LED device 100. As described below, a reflective layer 127 is provided below the green LED light-emitting layer 130, and a reflective layer 133 is provided above the green LED light-emitting layer 130. Light emitted from the green LED light-emitting layer 130 is reflected toward the sidewalls of the green LED light-emitting layer 130 between the two reflective layers 127 and 133.

[0193] In some embodiments, light emitted from the blue LED light-emitting layer 136 can propagate horizontally toward the sidewalls of the blue LED light-emitting layer 136, and then be reflected upwards by reflective elements such as 146 and / or 148 as described below, and emitted at the top surface of the single-pixel tri-color LED device 100. As described below, a reflective layer 135 is provided below the blue LED light-emitting layer 136. Light emitted from the blue LED light-emitting layer 136 is reflected toward the sidewalls of the blue LED light-emitting layer 136 between the reflective layer 135 and the upper surface of the blue LED light-emitting layer 136.

[0194] In some embodiments, light emitted from the red LED light-emitting layer 112 can propagate vertically through the green LED light-emitting layer 130 and then through the blue LED light-emitting layer 136 before being emitted from the tri-color LED device 100. In some embodiments, light emitted from the green LED light-emitting layer 130 can propagate through the blue LED light-emitting layer 136 to be emitted from the tri-color LED device 100. In the case of vertical light transmission, in some preferred embodiments, top reflective layers above each light-emitting layer, such as 115 and 133, are not included in the tri-color LED device 100.

[0195] In some embodiments, the LED light-emitting layer, such as 112, 130, and 136, comprises a plurality of sub-epitaxial layers with different compositions. Examples of LED epitaxial layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. Examples of microLEDs include GaN-based UV / blue / green microLEDs, AlInGaP-based red / orange microLEDs, and GaAs or InP-based infrared (IR) microLEDs.

[0196] In some embodiments, each LED structure in the stacked LED structure can be controlled individually to produce its own light. In some embodiments, the mixed light emitted from the top LED epitaxial layer can change the color of a single pixel within a small coverage area on the display panel due to the simultaneous operation of all LED epitaxial layers in the tri-color LED device 100.

[0197] In some embodiments, depending on the design of the LED device 100, the color of light emitted by the various LED structures included in the same device is not limited to red, green, and blue. For example, a suitable color can be selected from a range of different colors of light with wavelengths from 380 nm to 700 nm within the visible light range. In some embodiments, the LED structures may also emit other colors of light in the invisible range, such as ultraviolet and infrared light.

[0198] In some embodiments, when vertical and horizontal light emission are combined, for example, the choice of three colors from bottom to top may be red, green, and blue. In another embodiment, the choice of three colors from bottom to top may be infrared, orange, and ultraviolet. In some embodiments, the wavelength of light emitted by an LED structure on a certain layer of device 100 is longer than the wavelength of light emitted by an LED structure on the layer above it. For example, the wavelength of light emitted by the bottom LED light-emitting layer 112 is longer than the wavelength of light emitted by the middle LED light-emitting layer 130, and the wavelength of light emitted by the middle LED light-emitting layer 130 is longer than the wavelength of light emitted by the top LED light-emitting layer 136.

[0199] In some embodiments, when the light emission is horizontal or when the horizontally emitting portion exceeds the vertically emitting portion from the top surface of the LED device 100, each of the LED light-emitting layers 112, 130, and 136 can be any suitable visible or invisible color. The advantage of horizontal light emission is that since the emitted light does not need to pass through other upper layers of the LED device 100 but exits directly from the edge or sidewall of the current light-emitting layer, light propagation loss can be reduced, and luminous efficiency can be improved. For example, compared to vertically emitting LED devices, horizontally emitting LED devices can improve light propagation efficiency by 15%, 50%, 100%, 150%, or 200%. In some cases, the light propagation efficiency of horizontally emitting LED devices can be equal to or greater than 20%, 40%, or 60%.

[0200] In some embodiments, the bottom red LED light-emitting layer 112 is bonded to the substrate 104 via a metal bonding layer 108. The metal bonding layer 108 may be disposed on the substrate 104. In one method, the metal bonding layer 108 is grown on the substrate 104. In some embodiments, the metal bonding layer 108 is electrically connected to the driving circuit 106 on the substrate 104 and the red LED light-emitting layer 112 above the metal bonding layer 108, serving as a P-electrode. In some embodiments, the thickness of the metal bonding layer 108 is approximately 0.1 micrometers to 3 micrometers. In a preferred embodiment, the thickness of the metal bonding layer 108 is approximately 0.3 micrometers. The metal bonding layer 108 may include an ohmic contact layer and a metal bonding layer. In some cases, the metal bonding layer 108 includes two metal layers. One of the metal layers is deposited on a layer above the metal bonding layer within the LED device 100. A corresponding bonding metal layer is also deposited on the substrate 104. In some embodiments, the composition of the metal bonding layer 108 includes Au-Au bonding, Au-Sn bonding, Au-In bonding, Ti-Ti bonding, Cu-Cu bonding, or combinations thereof. For example, if Au-Au bonding is selected, the two Au layers require a Cr coating as an adhesive layer and a Pt coating as an anti-diffusion layer, respectively. The Pt coating is located between the Au layer and the Cr layer. The Cr layer and the Pt layer are located at the top and bottom of the two bonded Au layers. In some embodiments, when the two Au layers are of approximately the same thickness, the Au on the two layers diffuses into each other under high pressure and high temperature, bonding the two layers together. Eutectic bonding, thermocompression bonding, and transient liquid phase (TLP) bonding are exemplary techniques that can be used.

[0201] In some embodiments, the metal bonding layer 108 may also be used as a reflector to reflect light emitted from the LED structure above.

[0202] In some embodiments, a conductive layer 110 for electrode connection is formed at the bottom of the red LED light-emitting layer 112. In some embodiments, the conductive layer 110 may be an opaque metal layer that is opaque to the light emitted by the LED device 100. In some embodiments, the conductive layer 110 may be a conductive transparent layer, such as an indium tin oxide (ITO) layer, that is transparent to the light emitted by the LED device 100, formed between the red LED light-emitting layer 112 and the metal bonding layer 108 to improve conductivity and light transmittance.

[0203] exist Figures 1A to 1C In some embodiments not shown, the red LED structure has a P-electrode contact pad 168 electrically connected to the red LED light-emitting layer 112. In some embodiments, the P-electrode contact pad 168 is connected to the conductive layer 110. In some embodiments, a conductive layer 114 for electrode connection is formed on top of the red LED light-emitting layer 112. In some embodiments, the conductive layer 114 may be as follows: Figure 1CA metal layer or conductive transparent layer, such as an ITO layer, is shown for improving conductivity and light transmittance, formed between the red LED light-emitting layer 112 and the N-electrode contact pad 116. In some embodiments, the N-electrode contact pad, such as 116, is made of graphene, ITO, AZO, or FTO, or any combination of the above materials.

[0204] In some embodiments, a reflective layer 109 is provided below the red LED light-emitting layer 112, between the conductive layer 110 and the metal bonding layer 108, and a reflective layer 115 is provided above the red LED light-emitting layer 112, between the conductive layer 114 and the bonding layer 156.

[0205] In some embodiments, the red LED emitting layer 112 has an extension 164 on one side relative to the other layers above it, such as... Figure 1C As shown. In some embodiments, the extension 164 extends together with the conductive layers 110 and 114. In some embodiments, the extension 164 extends together with the reflective layer 109 and the metal bonding layer 108 at the bottom of the red LED light-emitting layer 112. In some embodiments, the red LED light-emitting layer 112 is connected to the N-electrode contact pad 116 through the extension of the conductive layer 114 above the extension 164.

[0206] In one method, the red LED light-emitting layer 112 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 1B and Figure 1C The structure shown.

[0207] In some embodiments, the red LED emitting layer 112 is used to form a red microLED. Examples of red LED emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the red LED emitting layer 112 may comprise layers of P-type GaP / P-type AlGaInP / AlGaInP / N-type AlGaInP / N-type GaAs. In some embodiments, the P-type layer is typically Mg-doped, while the N-type layer is typically Si-doped. In some examples, the thickness of the red LED emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the red LED emitting layer is approximately 0.3 micrometers.

[0208] In some embodiments, the red LED structure includes a metal bonding layer 108, a reflective layer 109, a conductive layer 110, a red LED light-emitting layer 112, a conductive layer 114, a reflective layer 115, and an N-electrode contact pad 116.

[0209] In some embodiments, bonding layer 156 is used to bond the red LED structure and the green LED structure together. In some embodiments, bonding layer 156 is opaque to light emitted from LED device 100. In some embodiments, the material and thickness of bonding layer 156 are the same as described above for metallic bonding layer 108. In some embodiments, bonding layer 156 may also be used as a reflector to reflect light emitted by the upper LED structure.

[0210] In some embodiments, when vertical propagation is used, the bonding layer 156 is transparent to the light emitted by the microLED 100. In some embodiments, the bonding layer 156 is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes SiO2, Al2O3, Si3N4, phosphosilicate glass (PSG), or borosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or Micro Resist's bonding adhesive BCL-1200, or any combination thereof. In some embodiments, the transparent bonding layer may facilitate the passage of light emitted from layers beneath the bonding layer.

[0211] In some embodiments, such as Figure 1A and Figure 1B As shown, the green LED structure has a P-electrode contact pad 126 electrically connected to the green LED light-emitting layer 130. In some embodiments, the P-electrode contact pad 126 is connected to a conductive layer 128. In some embodiments, the conductive layer 128 for electrode connection is formed on the bottom of the green LED light-emitting layer 130. In some embodiments, such as Figure 1A and 1B As shown, the conductive layer 128 may be a conductive transparent layer or a metal layer, such as an ITO layer, used to improve conductivity and light transmittance, and is formed between the green LED light-emitting layer 130 and the P electrode contact pad 126.

[0212] In some embodiments, the conductive layer 128 has an extension 128-1 on one side relative to the other layers above, such as Figure 1B As shown. In some embodiments, the extension 128-1 extends together with all layers below the conductive layer 128 within the LED device 100. In some embodiments, the green LED light-emitting layer 130 is electrically connected to the P-electrode contact pad 126 via the extension 128-1 of the conductive layer 128. In some embodiments, the P-electrode contact pad 126 is also electrically connected to the driving circuit 106 in the substrate 104.

[0213] In some embodiments, an insulating layer 174 made of a dielectric material, such as a SiO2 layer, is deposited on the surface of the LED device 100. A P-electrode contact pad 126 extends from its contact with the drive circuit 106 to its contact with the conductive layer 128 through vias or channels within the insulating layer 174. The P-electrode contact pad 126 does not contact other layers within the LED device 100.

[0214] In some embodiments, a conductive layer 132 for electrode connection is formed on top of the green LED light-emitting layer 130. In some embodiments, the conductive layer 132 may be a conductive transparent layer such as an ITO layer or a metal layer, formed between the green LED light-emitting layer 130 and the N-electrode contact pad 120 to improve conductivity and light transmittance. In some embodiments, the N-electrode contact pad 120 is made of a transparent conductive material such as ITO. In some embodiments, the N-electrode contact pad 120 is made of a material such as graphene, ITO, AZO, or FTO, or any combination thereof.

[0215] In some embodiments, such as Figure 1C As shown, the green LED structure has an N-electrode contact pad 120 electrically connected to the green LED light-emitting layer 130. In some embodiments, the N-electrode contact pad 120 is connected to the conductive layer 132. In some embodiments, the N-electrode contact pad 120 of the green LED structure is also electrically connected to the N-electrode contact pad 116 of the red LED structure.

[0216] like Figure 1C As shown, in some embodiments, the green LED light-emitting layer 130 has an extension 166 on one side. In some embodiments, the extension 166 extends together with conductive layers 128 and 132 and all other layers below conductive layer 128. In some embodiments, the extension 166 is electrically connected to the N-electrode contact pad 120 via an extension of conductive layer 132 above the extension 166.

[0217] In some embodiments, the lateral dimension of the green LED light-emitting layer 130 is smaller than the lateral dimension of the red LED light-emitting layer 112.

[0218] In some embodiments, a reflective layer 127 is provided below the green LED light-emitting layer 130, between the conductive layer 128 and the bonding layer 156, and a reflective layer 133 is provided above the green LED light-emitting layer 130, between the conductive layer 132 and the bonding layer 160.

[0219] In one method, the green LED light-emitting layer 130 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 1B and Figure 1C The structure shown.

[0220] In some embodiments, the green LED light-emitting layer 130 is used to form a green microLED. Examples of green LED light-emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the green LED light-emitting layer 130 may comprise a layer of P-type GaN / InGaN light-emitting layer / N-type GaN. In some embodiments, the P-type is typically Mg-doped, while the N-type is typically Si-doped. In some examples, the thickness of the green LED light-emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the green LED light-emitting layer is approximately 0.3 micrometers.

[0221] In some embodiments, the green LED structure includes a reflective layer 127, a conductive layer 128, a green LED light-emitting layer 130, a conductive layer 132, a reflective layer 133, a P-electrode contact pad 126, and an N-electrode contact pad 120.

[0222] In some embodiments, excluding the extensions below 128-1 of conductive layer 128 such as 164, 166, and 128, the first LED structure, for example, a red LED structure, and the second LED structure, for example, a green LED structure, have the same central axis. In some embodiments, excluding the extensions below 128-1 of conductive layer 128 such as 164, 166, and 128, the first LED structure and the second LED structure are aligned along the same central axis.

[0223] In some embodiments, bonding layer 160 is used to bond the green LED structure and the blue LED structure together. In some embodiments, bonding layer 156 is opaque to light emitted by LED device 100. In some embodiments, the material and thickness of bonding layer 160 are the same as described above for metal bonding layer 108. In some embodiments, bonding layer 160 may also be used as a reflector to reflect light emitted by the LED structure above.

[0224] In some embodiments, when vertical propagation is used, the bonding layer 160 is transparent to light emitted by the LED device 100. In some embodiments, the bonding layer 160 is made of a dielectric material such as a solid inorganic material or a plastic material, as described above for the bonding layer 156. In some embodiments, the transparent bonding layer may facilitate the passage of light emitted from layers beneath the bonding layer.

[0225] In some embodiments, such as Figure 1A and Figure 1BAs shown, the blue LED structure has a P-electrode contact pad 152 electrically connected to the blue LED light-emitting layer 136. In some embodiments, the P-electrode contact pad 152 is connected to a conductive layer 134. In some embodiments, a conductive layer 134 for electrode connection is formed at the bottom of the blue LED light-emitting layer 136. In some embodiments, such as Figure 1A and 1B As shown, the conductive layer 134 can be a conductive transparent layer such as an ITO layer or a metal layer, formed between the blue LED light-emitting layer 136 and the P electrode contact pad 152 to improve conductivity and light transmittance.

[0226] In some embodiments, the conductive layer 134 has an extension 134-1 on one side relative to the other layers above it, such as Figure 1B As shown. In some embodiments, the extension 134-1 extends together with all layers below the conductive layer 134 within the LED device 100. In some embodiments, the blue LED light-emitting layer 136 is electrically connected to the P-electrode contact pad 152 through the extension 134-1 of the conductive layer 134. In some embodiments, the P-electrode contact pad 152 is also electrically connected to the driving circuit 106 in the substrate 104.

[0227] In some embodiments, an insulating layer 174 made of a dielectric material, such as a SiO2 layer, is deposited on the surface of the LED device 100. A P-electrode contact pad 152 extends from its contact with the drive circuit 106 to its contact with the conductive layer 134 through vias or channels within the insulating layer 174. The P-electrode contact pad 152 does not contact other layers within the LED device 100.

[0228] In some embodiments, a conductive layer 138 for electrode connection is formed on top of the blue LED light-emitting layer 136. In some embodiments, the conductive layer 138 may be a conductive transparent layer such as an ITO layer or a metal layer, formed between the blue LED light-emitting layer 136 and the N-electrode contact pad 140 to improve conductivity and light transmittance. In some embodiments, the N-electrode contact pad 140 is made of a transparent conductive material such as ITO. In some embodiments, the N-electrode contact pad 140 is made of a material such as graphene, ITO, AZO, or FTO, or any combination thereof. In some embodiments, the N-electrode contact pads 116, 120, and 140 are all electrically connected together as a common N-electrode. In some embodiments, the N-electrode contact pads 116, 120, and 140 are formed as a single integral element as a common N-electrode.

[0229] In some embodiments, such as Figure 1B As shown, the blue LED structure has an N-electrode contact pad 140 electrically connected to the blue LED light-emitting layer 136. In some embodiments, the N-electrode contact pad 140 is connected to the conductive layer 138.

[0230] In some embodiments, the lateral dimension of the blue LED light-emitting layer 136 is smaller than the lateral dimension of the green LED light-emitting layer 130.

[0231] In some embodiments, the top electrode element, such as the N-electrode pad 140, is connected via an electrical connection element beneath an optical isolation structure such as 146, 148, 170, and 172. In some embodiments, the top electrode is connected via an electrical connection element embedded in the substrate 104. In one example, the top electrode 140 is connected via an electrical connection element located above the insulating layer 174, beneath an optical isolation structure such as 146, 148, 170, and 172.

[0232] In some embodiments, a reflective layer 135 is provided below the blue LED light-emitting layer 136, between the conductive layer 134 and the bonding layer 160. In some embodiments, an optional reflective layer 139 is provided on top of the conductive layer 138 above the blue LED light-emitting layer 136. Figure 1A-1C (Not shown in the image).

[0233] In one method, the blue LED light-emitting layer 136 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 1B and Figure 1C The structure shown.

[0234] In some embodiments, the blue LED emitting layer 136 is used to form a blue microLED. Examples of the blue LED emitting layer include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the blue LED emitting layer 136 may comprise a layer of P-type GaN / InGaN emitting layer / N-type GaN. In some embodiments, the P-type is typically Mg-doped, while the N-type is typically Si-doped. In some examples, the thickness of the blue LED emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the blue LED emitting layer is approximately 0.3 micrometers.

[0235] In some embodiments, the blue LED structure includes a reflective layer 135, a conductive layer 134, a blue LED emitting layer 136, a conductive layer 138, an optional reflective layer 139, a P-electrode contact pad 152, and an N-electrode contact pad 140.

[0236] In some embodiments, excluding the extension below 134-1 such as 166 and conductive layer 134, the second LED structure, for example a green LED structure, and the third LED structure, for example a blue LED structure, have the same central axis. In some embodiments, excluding the extension below 134-1 such as 166 and conductive layer 134, the first LED structure and the second LED structure are aligned along the same central axis.

[0237] In some embodiments, the N electrode 140 covers the top of the tri-color LED device 100. In some embodiments, the N electrode 140 is connected via electrical connection elements to the N electrode in an adjacent tri-color LED device (in... Figure 1A-1C (Not shown in the image), serving as the common electrode.

[0238] In some embodiments, the thickness of each conductive layer 110, 114, 128, 132, 134, and 138 is approximately 0.01 micrometers to 1 micrometer. In some cases, each conductive layer 110, 114, 128, 132, 134, and 138 is typically deposited on its respective epitaxial layer by a vapor deposition process, such as electron beam evaporation or sputtering, prior to any bonding process with the next epitaxial layer. In some examples, the conductive layers are used to maintain good conductivity of the electrode connections, while in other cases, they are also used to improve the optical properties of the LED device, such as reflectivity or transmittance.

[0239] In some embodiments, an additional dielectric layer, such as a SiO2 layer, is formed above the bottom light-emitting layer 112 (and above the conductive layer 114), preferably above the reflective layer 115 and below the bonding layer 156. Figure 1A-1C (Not shown in the diagram), the N-type layer of the light-emitting layer 112 is electrically separated from the bonding layer 156. In some embodiments, the thickness of the additional dielectric layer is 20 nanometers to 2 micrometers. In a preferred embodiment, the thickness of the additional dielectric layer is approximately 100 nanometers. In some embodiments, an additional dielectric layer, such as a SiO2 layer, is formed above the intermediate light-emitting layer 130 (and above the conductive layer 132), preferably above the reflective layer 133 and below the bonding layer 160. Figure 1A-1C (Not shown in the diagram), the N-type layer of the light-emitting layer 130 is electrically separated from the bonding layer 160. In some embodiments, the thickness of the additional dielectric layer is 20 nanometers to 2 micrometers. In a preferred embodiment, the thickness of the additional dielectric layer is approximately 100 nanometers.

[0240] In some embodiments, to improve the luminous efficiency of the tri-color LED device 100, optical isolation structures such as 146, 148, 170, and 172, as further described below, are formed along the sidewalls of the tri-color LED device 100. In some embodiments, such optical isolation structures as 146, 148, 170, and 172 are made of a dielectric material such as SiO2.

[0241] As in Figure 1A As shown in the top view, in some embodiments, the tri-color LED device 100 has a circular shape. In some embodiments, optical isolation structures such as 146, 148, 170, and 172 are integrated and form a circular sidewall surrounding the tri-color LED device 100. In some embodiments, the optical isolation structures form a reflector cup, which is described in further detail below. In some embodiments, the three stacked LED structures within the tri-color LED device 100 are also circular. In some embodiments, the tri-color LED device 100 may have other shapes, such as rectangular, square, triangular, trapezoidal, or polygonal. In some embodiments, optical isolation structures such as 146, 148, 170, and 172 are integrated and form a sidewall surrounding the tri-color LED device 100 in other shapes such as rectangular, square, triangular, trapezoidal, or polygonal.

[0242] like Figure 1B and Figure 1C As shown, in some embodiments, the red LED light-emitting layer 112, the green LED light-emitting layer 130, and the blue LED light-emitting layer 136 have inclined side surfaces. As used herein, an inclined side surface can refer to a surface that is not perpendicular to the top or bottom surface of the respective LED light-emitting layer. In some embodiments, the angle between the inclined sidewall and the bottom surface of the respective LED light-emitting layer is less than 90 degrees. In some embodiments, bonding layers 108, 156, and 160 also have inclined side surfaces. The inclined side surfaces facilitate the connection of different connecting elements to each LED light-emitting layer, prevent the connection from breaking due to abrupt angles, and enhance the overall stability of the device.

[0243] In some embodiments, the light propagation efficiency of the multicolor LED device changes with the angle between the tilted side surface of the LED light-emitting layer and the surface normal of the substrate 104. In some embodiments, the light propagation efficiency of the multicolor LED device increases with the increase of the angle between the tilted side surface of the LED light-emitting layer and the normal of the surface of the substrate 104. For example, when the angle between the side surface of the LED light-emitting layer and the normal of the surface of the substrate 104 is ±5 degrees and when the optical isolation structures such as 146, 148, 170 and / or 172 are not the reflectors as described below, the luminous efficiency of the multicolor LED device is 0.32%. For example, when the angle between the side surface of the LED light-emitting layer and the normal of the surface of the substrate 104 is ±15 degrees and when the optical isolation structures such as 146, 148, 170 and / or 172 are not the reflectors as described below, the luminous efficiency of the multicolor LED device is 2.7%. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 104 is (e.g., when the light-emitting layer is tilted) or very close to ±90 degrees and when the optical isolation structures such as 146, 148, 170 and / or 172 are not reflectors as described below, the luminous efficiency of the multicolor LED device is equal to or very close to 56.4%.

[0244] In contrast, the implementation of the reflector structure, as described in further detail below, improves the light propagation efficiency of the multicolor LED device. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 104 is ±5 degrees and when the optical isolation structures such as 146, 148, 170, and / or 172 are reflectors as described below, the luminous efficiency of the multicolor LED device is 0.65%, which is an increase of 104.6% compared to an LED device without a reflector. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 104 is ±15 degrees and when the optical isolation structures such as 146, 148, 170, and / or 172 are reflectors as described below, the luminous efficiency of the multicolor LED device is 6.65%, which is an increase of 144.4% compared to an LED device without a reflector. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 104 is (e.g., when the light-emitting layer is tilted) or very close to ±90 degrees and when the optical isolation structure such as 146, 148, 170 and / or 172 is a reflector cup as described below, the luminous efficiency of the multicolor LED device is equal to or very close to 66.65%, that is, an increase of 18.4% compared to an LED device without a reflector cup.

[0245] In some embodiments, reflective layers are formed above and below each LED light-emitting layer to improve light propagation efficiency. For example... Figure 1B and 1CAs shown, in some embodiments, a reflective layer 109 is formed between the bonding layer 108 and the red LED light-emitting layer 112. In some embodiments, the reflective layer 109 is formed between the bonding layer 108 and the conductive layer 110 in the presence of the conductive layer 110. In some embodiments, a reflective layer 115 is formed between the bonding layer 156 and the red LED light-emitting layer 112 in the presence of the conductive layer 114. In some embodiments, the reflective layer 115 is formed between the bonding layer 156 and the conductive layer 114 in the presence of the conductive layer 114.

[0246] In some embodiments, a reflective layer 127 is formed between the bonding layer 156 and the green LED light-emitting layer 130. In some embodiments, if a conductive layer 128 is present, the reflective layer 127 is formed between the bonding layer 156 and the conductive layer 128. In some embodiments, a reflective layer 133 is formed between the bonding layer 160 and the green LED light-emitting layer 130. In some embodiments, if a conductive layer 132 is present, the reflective layer 133 is formed between the bonding layer 160 and the conductive layer 132.

[0247] In some embodiments, a reflective layer 135 is formed between the bonding layer 160 and the blue LED light-emitting layer 136. In some embodiments, if a conductive layer 134 is present, the reflective layer 135 is formed between the bonding layer 160 and the conductive layer 134. In some embodiments, an optional reflective layer 139 is formed between the N-electrode pad 140 and the blue LED light-emitting layer 136. Figure 1B-1C (Not shown in the image), while still allowing the blue LED emitting layer 136 to be electrically connected to the N electrode pad 140, for example, via a conductive path. In some embodiments, in the presence of the conductive layer 138, an optional reflective layer 139 is formed between the N electrode pad 140 and the conductive layer 138, while still allowing the conductive layer 138 to be electrically connected to the N electrode pad 140, for example, via a conductive path.

[0248] In some embodiments, the materials of reflective layers 109, 115, 127, 133, 135, and 139 have high reflectivity, especially for light emitted by a single pixel tri-color LED device 200. For example, the reflectivity of reflective layers 109, 115, 127, 133, 135, and 139 is greater than 60%. In another example, the reflectivity of reflective layers 109, 115, 127, 133, 135, and 139 is greater than 70%. In yet another example, the reflectivity of reflective layers 109, 115, 127, 133, 135, and 139 is greater than 80%.

[0249] In some embodiments, the materials of reflective layers 109, 115, 127, 133, 135, and 139 are selected from one or more metals chosen from the group consisting of Rh, Al, Ag, and Au. In some embodiments, any one of the reflective layers 109, 115, 127, 133, 135, and 139 may comprise at least two sublayers with different refractive indices. Each sublayer also has a high reflectivity, such as above 60%, 70%, or 80%.

[0250] In some embodiments, each reflective layer, such as 109, 115, 127, 135, and 139, is coated on both sides of each light-emitting layer in the light-emitting layers such as 112, 130, and 136, or, in the case of including conductive layers, is coated on both sides of conductive layers 110, 114, 128, 132, 134, and 138 prior to bonding. In some cases, the thickness of each reflective layer in the reflective layers such as 109, 115, 127, 133, 135, and 139 is approximately 2 nanometers (nm) to 5 micrometers (µm). In some embodiments, the thickness of each reflective layer in the reflective layers such as 109, 115, 127, 133, 135, and 139 is equal to or less than 1 micrometer. In some preferred embodiments, the thickness of each layer in the reflective layers such as 109, 115, 127, 133, 135, and 139 is approximately 5 nanometers (nm) to 10 nm.

[0251] In some embodiments, any one of the reflective layers such as 109, 115, 127, 133, 135, and 139 comprises a distributed Bragg reflector (DBR) structure. For example, any one of the reflective layers such as 109, 115, 127, 133, 135, and 139 is formed of alternating layers or layers of different materials with different refractive indices. In some cases, the boundaries of each layer in the DBR structure result in partial reflection of light waves. Reflective layers such as 109, 115, 127, 133, 135, and 139 can be used to reflect selected wavelengths, for example, reflective layers 109 and 115 for red light, reflective layers 127 and 133 for green light, and reflective layers 135 and 139 for blue light. In some embodiments, any one of the reflective layers such as 109, 115, 127, 133, 135, and 139 is made of multiple layers, for example, at least two layers of SiO2 and Ti3O5, respectively. By changing the thickness and number of SiO2 and Ti3O5 layers respectively, selective reflection or selective propagation of light of different wavelengths can be achieved.

[0252] In some embodiments, any one of the reflective layers such as 109, 115, 127, 133, 135, and 139 further includes a transparent layer on one of the high-reflectivity sublayers. For example, the transparent layer preferably formed on one or both sides of any one of the reflective layers such as 109, 115, 127, 133, 135, and 139 is selected from one or more of ITO and SiO2.

[0253] In some embodiments, each of the reflective layers 109 and 115 for the red LED comprises multiple layers of Au and / or indium tin oxide (ITO).

[0254] In some embodiments, each of the reflective layers 109 and 115 in the red LED structure has low absorbance (e.g., equal to or less than 25%) for light generated by different layers of the tri-color LED device 100. In some embodiments, each of the reflective layers 109 and 115 in the red LED structure has high reflectivity (e.g., equal to or greater than 75%) for light generated between the current two reflective layers 109 and 115, such as red light.

[0255] In one example, the following DBR structure shown in Table 1 is used to reflect green light from a green LED:

[0256] Table 1: DBR layer structure used for green LED reflective layer.

[0257]

[0258]

[0259] In some embodiments, each of the reflective layers 127 and 133 in the green LED structure has low absorbance (e.g., equal to or less than 25%) for light generated by different layers of the tri-color LED device 100. In some embodiments, each of the reflective layers 127 and 133 in the green LED structure has high reflectivity (e.g., equal to or greater than 75%) for light generated between the current two reflective layers 127 and 133, such as green light.

[0260] In one example, the following DBR structure shown in Table 2 is used to reflect blue light from a blue LED:

[0261] Table 2: DBR layer structure used for blue LED reflective layer.

[0262]

[0263] In some embodiments, each of the reflective layers 135 and optionally 139 in the blue LED structure has low absorbance (e.g., equal to or less than 25%) for light generated by different layers of the tri-color LED device 100. In some embodiments, the reflective layer 135 in the blue LED structure has high reflectivity (e.g., equal to or greater than 75%) for light generated above the current reflective layer 135 or between the current reflective layers 135 and 139, such as blue light.

[0264] Figure 2A A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A A cross-sectional view of the mid-diagonal 102. In some embodiments, the single-pixel tri-color LED device 100 has a cross-sectional view of the mid-diagonal 102. Figure 1A , 1B It has a structure similar to the single-pixel tri-color LED device 100 shown in 1C, but adds a planarization layer 176 covering the single-pixel tri-color LED device 100.

[0265] Figure 2B A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A A cross-sectional view along the mid-diagonal 150. In some embodiments, the single-pixel tri-color LED device 100 has a... Figure 1A , 1B It has a structure similar to the single-pixel tri-color LED device 100 shown in 1C, but adds a planarization layer 176 covering the single-pixel tri-color LED device 100.

[0266] In some embodiments, the planarization layer, such as 176, is transparent to the light emitted by the microLED 100. In some embodiments, the planarization layer is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes SiO2, Al2O3, Si3N4, phosphosilicate glass (PSG), or borosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or Micro Resist's bonding adhesive BCL-1200, or any combination thereof. In some embodiments, the planarization layer may facilitate the passage of light emitted by the microLED 100.

[0267] In some embodiments, the planarization layer 176 has the same height as the optical isolation structures, such as 146, 148, 170, and 172, relative to the surface of the substrate 104. For example, the planarization layer 176 covers the entire single-pixel tri-color LED device 100 and the sidewalls of the optical isolation structure. The planarization layer 176 is on the same plane as the top surface of the optical isolation structure.

[0268] Figure 3A A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A A cross-sectional view of the mid-diagonal 102. In some embodiments, the single-pixel tri-color LED device 100 has a cross-sectional view of the mid-diagonal 102. Figure 1A , 1B It has a structure similar to the single-pixel tri-color LED device 100 shown in 1C, but adds a planarization layer 178 covering the single-pixel tri-color LED device 100.

[0269] Figure 3B A single-pixel tri-color LED device 100 with planar features according to some embodiments. Figure 1A A cross-sectional view along the mid-diagonal 150. In some embodiments, the single-pixel tri-color LED device 100 has a... Figure 1A , 1B It has a structure similar to the single-pixel tri-color LED device 100 shown in 1C, but adds a planarization layer 178 covering the single-pixel tri-color LED device 100.

[0270] In some embodiments, planarization layer 178 has the same height as, for example, the top electrode element of 140. Planarization layer 178 lies on the same plane as the top surface of the top electrode element, such as N-electrode pad 140. In some embodiments, the top electrode element, such as 140, is directly on top of planarization layer 178. Planarization layer 178 lies on the same plane as the bottom surface of the top electrode element, such as N-electrode pad 140. For example, planarization layer 178 covers the entire single-pixel tri-color LED device 100 and a portion of the sidewalls of optical isolation structures such as 146, 148, 170, and 172.

[0271] With Figure 1A-1C The top electrode elements, such as N-electrode pad 140, shown are connected differently via electrical connection elements beneath optically insulating structures such as 146, 148, 170, and 172. Figure 2A-2BIn embodiments 3A-3B, the top electrode element, such as the N-electrode pad 140, is connected via electrical connection elements on at least the sidewalls of optical isolation structures such as 146, 148, 170, and 172. In some embodiments, the N-electrode pad 140 is fixed to or attached to the surface of optical isolation structures such as 146, 148, 170, and 172 via the surface of the optical isolation structures. The top electrode structure simplifies the manufacturing process, particularly with its planarized layers, enabling a compact single-pixel tri-color LED device 100.

[0272] In some embodiments, the insulating layer can be deposited on a single-pixel multicolor LED device by depositing it on each LED light-emitting layer and other layers such as conductive and reflective layers. A planarization process is then performed to flatten the surface of the insulating layer embedded in the single-pixel multicolor LED device. Vias for electrical connections are also formed within each planarized layer. Compared to insulating layers without planarization using other processes, features and layers within the planarized LED structure are better protected and less susceptible to external destructive forces. Furthermore, the planarized surface can provide light propagation efficiency by reducing deflection caused by uneven surfaces.

[0273] In some embodiments, a tri-color LED structure is formed by dry etching and wet etching, with the axes of the different colored LED structures vertically aligned with each other. In some embodiments, the different colored LED structures share the same axis.

[0274] In some embodiments, each LED structure in the different color LED structure is formed in a pyramid shape or a trapezoidal cross-section. Each layer has a narrower width or a smaller area compared to the layer below it. In this case, the width or area is measured by the dimensions of a plane parallel to the surface of the substrate 104.

[0275] In some embodiments, each of the multiple LED structures of different colors is bonded together by a bonding layer that covers only the area of ​​the LED structure without any extension beyond the area of ​​the LED structure, forming the entire multicolor LED device in a pyramid (or inverted cone) shape or a trapezoidal cross-section (as shown in Figures 1-3). In some embodiments, for example, the lateral dimension of the bottom LED structure of the red LED structure may be the longest, and the lateral dimension of the top LED structure of the blue LED structure may be the shortest. The pyramid shape can be naturally formed from bottom to top as the individual layers within the LED device are etched and patterned. The pyramidal structure can improve the electrical connection between individual LED structures and with electrodes, and simplify the manufacturing process. For example, electrode connection elements in each layer are exposed in each layer for easy connection.

[0276] In some embodiments, the bottom layer, such as the metal bonding layer 108, has a lateral dimension of about 1 micrometer to 500 micrometers. In a preferred embodiment, the lateral dimension of the metal bonding layer 108 at the bottom of the multicolor LED device is about 1.75 micrometers. In some embodiments, the vertical height of the multicolor LED device is about 1 micrometer to 500 micrometers. In a preferred embodiment, the vertical height of the multicolor LED device is about 1.9 micrometers. In a preferred embodiment, the lateral dimension of the conductive layer 138 at the top of the multicolor LED device is about 1.0 micrometer.

[0277] In some embodiments, the aspect ratio of the layers in a tri-color LED device remains substantially the same when the lateral dimensions of the same layer vary. For example, when the lateral dimension of a patterned epitaxial layer is 5 micrometers, the thickness of the patterned epitaxial layer is less than one micrometer. In another example, when the lateral dimension of the same patterned epitaxial layer increases, the thickness of the patterned epitaxial layer increases accordingly to maintain the same aspect ratio. In some embodiments, the aspect ratio of the epitaxial layer and other layers is less than 1 / 5 of the thickness / width.

[0278] The shape of the LED device is not limited. In some other embodiments, the cross-sectional shape of the tri-color LED device can be other shapes, such as inverted trapezoid, semi-ellipse, rectangle, parallelogram, triangle or hexagon, etc.

[0279] In some embodiments, the top conductive layer 138 above the third LED light-emitting layer 136 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is, for example, dry etching such as inductively coupled plasma (ICP) etching or wet etching with an ITO etching solution. In some embodiments, the same patterning method can be applied to all other conductive layers within the tri-color LED device 100, including conductive layers 110, 114, 128, 132, 134, and 138.

[0280] In some embodiments, the blue LED light-emitting layer 136 and the green LED light-emitting layer 130 are patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using Cl2 and BC13 etching gases.

[0281] In some embodiments, the bonding layers including 160 and 156 are patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases.

[0282] In some embodiments, the reflective layers including 109, 115, 127, 133, 135, and 139 are patterned using photolithography and etching. In some cases, the etching method used to form the pattern for the reflective layers, particularly the DBR layers, is dry etching, such as inductively coupled plasma (ICP) etching using CF4 and O2 etching gases or ion beam etching (IBE) using Ar gas.

[0283] In some embodiments, the red LED light-emitting layer 112 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using Cl2 and HBr etching gases.

[0284] In some embodiments, the metal bonding layer 108 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, such as inductively coupled plasma (ICP) etching using C12 / BC13 / Ar etching gas, or ion beam etching (IBE) using Ar gas.

[0285] In some embodiments, after each LED device structure in each LED device structure is patterned, an insulating layer such as 174, 176, or 178 is deposited on the surface of each patterned LED structure, including all patterned layers, sidewalls, and exposed substrate. In some embodiments, the insulating layer is made of SiO2 and / or Si3N4. In some embodiments, the insulating layer is made of TiO2. In some embodiments, an insulating layer having a composition similar to SiO2 is formed after curing a layer such as SOG at a high temperature. In some embodiments, the insulating layer is made of a material having a thermal coefficient similar to that of the layers below the insulating layer. The surfaces of the insulating layers such as 176 and 178 are then smoothed or planarized by methods such as chemical mechanical polishing, as understood by those skilled in the art.

[0286] In some embodiments, the planarized insulating layers, such as 176 and 178, are patterned using photolithography and etching to expose the electrode contact areas. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2.

[0287] In some embodiments, the P-electrode or anode metal pad is deposited at appropriate locations on the patterned LED structure, such as on one side within a planarized insulating layer and / or in a via, using vapor deposition or other deposition methods, to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0288] In some embodiments, individual N-electrodes or cathode metal pads are deposited using vapor deposition or other deposition methods at appropriate locations on the patterned LED structure, such as on one side / top and / or in vias within a planarized insulating layer, to electrically connect the red LED structure, green LED structure, and blue LED structure.

[0289] Figure 4A This is a top view of a layered planarized single-pixel tri-color LED device 400 according to some embodiments.

[0290] Figure 4B It is a layered planarized single-pixel tri-color LED device 400 according to some embodiments. Figure 4A Cross-sectional view of the middle diagonal 402. This diagonal passes through the center of the single-pixel tri-color LED device 400.

[0291] Compared to the embodiments depicted in Figures 1-3, Figures 4A-4B The main difference in the embodiment is that each LED structure in the different colored LED structures is embedded in a corresponding planarized insulating layer, and the planarized insulating layers with LED structures inside are bonded together by some bonding layers.

[0292] In some embodiments, the tri-color LED device 400 includes a substrate 404. For convenience, "upward" is used to indicate away from the substrate 404, and "downward" indicates towards the substrate 404; other directional terms such as top, bottom, above, below, directly below, and under are also interpreted accordingly. The support substrate 404 is a substrate on which an array of various driving circuits 406 are fabricated. In some embodiments, the driving circuits may also be located in one of the layers above the substrate 404, or above the micro tri-color LED structure 400. Each driving circuit is a pixel driver 406. In some cases, the driving circuit 406 is a thin-film transistor pixel driver or a silicon CMOS pixel driver. In one embodiment, the substrate 404 is a Si substrate. In another embodiment, the support substrate 404 is a transparent substrate, such as a glass substrate. Examples of other substrates include GaAs, GaP, InP, SiC, ZnO, and sapphire substrates. In some embodiments, the substrate 404 is about 700 micrometers thick. The driving circuits 406 form the individual pixel drivers to control the operation of the individual pixel tri-color LED device 400. The circuitry on substrate 404 includes contacts for each individual drive circuit 406 and ground contacts. For example... Figure 4A and Figure 4BAs shown, each miniature tricolor LED structure 400 also has two types of contacts: P-electrodes or anodes such as 450 (or 408), 452 connected to the pixel driver and combined portions 422, 424 and 426; and N-electrodes such as 440, 442, 444 connected to ground (i.e., the common electrode) or cathodes and combined portions 416, 418 and 420.

[0293] In some embodiments, the N-electrode (or N-electrode contact pad) and its connecting components, such as 440, 442, 444, and the combined portions 416, 418, and 420, are made of materials such as graphene, ITO, aluminum-doped zinc oxide (AZO), or fluorine-doped tin oxide (FTO), or any combination thereof. In some embodiments, the N-electrode (or N-electrode contact pad) and its connecting components, such as 440, 442, 444, and the combined portions 416, 418, and 420, are made of non-transparent or transparent conductive materials; in a preferred embodiment, they are made of transparent conductive materials. In some embodiments, the P-electrode (or P-electrode contact pad) and its connecting components, such as 450, 452, and the combined portions 422, 424, and 426, are made of materials such as graphene, ITO, AZO, or FTO, or any combination thereof. In some embodiments, the P electrode (or P electrode contact pad) and its connecting components, such as 450, 452 and the merged portions 422, 424 and 426, are made of a non-transparent or transparent conductive material, and in preferred embodiments, of a transparent conductive material. In some embodiments, the positions of the P electrode (or P electrode contact pad) and its connecting components and the N electrode (or N electrode contact pad) and its connecting components can be switched.

[0294] Typically, an LED light-emitting layer includes a PN junction having p-type regions / layers and n-type regions / layers, and an active layer between the p-type regions / layers and the n-type regions / layers.

[0295] In some embodiments, the light emitted by the red LED light-emitting layer 412 can propagate horizontally toward the sidewalls of the red LED light-emitting layer 412, and then be reflected upwards by reflective elements such as 446 and / or 448 as described below, and emitted at the top surface of the single-pixel tri-color LED device 400. As described below, a reflective layer 409 is provided below the red LED light-emitting layer 412, and a reflective layer 415 is provided above the red LED light-emitting layer 412. The light emitted by the red LED light-emitting layer 412 is reflected toward the sidewalls of the red LED light-emitting layer 412 between the two reflective layers 409 and 415.

[0296] In some embodiments, light emitted from the green LED light-emitting layer 430 can propagate horizontally toward the sidewalls of the green LED light-emitting layer 430, and then be reflected upwards by reflective elements such as 446 and / or 448 as described below, and emitted at the top surface of the single-pixel tri-color LED device 400. As described below, a reflective layer 427 is provided below the green LED light-emitting layer 430, and a reflective layer 433 is provided above the green LED light-emitting layer 430. Light emitted from the green LED light-emitting layer 430 is reflected toward the sidewalls of the green LED light-emitting layer 430 between the two reflective layers 427 and 433.

[0297] In some embodiments, light emitted from the blue LED light-emitting layer 436 can propagate horizontally toward the sidewalls of the blue LED light-emitting layer 436, and then be reflected upwards by reflective elements such as 446 and / or 448 as described below, and emitted at the top surface of the single-pixel tri-color LED device 400. As described below, a reflective layer 435 is provided below the blue LED light-emitting layer 436. Light emitted from the blue LED light-emitting layer 436 is reflected toward the sidewalls of the blue LED light-emitting layer 436 between the reflective layer 435 and the upper surface of the blue LED light-emitting layer 436.

[0298] In some embodiments, light emitted by the red LED light-emitting layer 412 can propagate vertically through the green LED light-emitting layer 430 and then through the blue LED light-emitting layer 436 to be emitted from the tri-color LED device 400. In some embodiments, light emitted by the green LED light-emitting layer 430 can propagate through the blue LED light-emitting layer 436 to be emitted from the tri-color LED device 400. In the case of vertical light propagation, in some preferred embodiments, top reflective layers such as 415 and 433 above each light-emitting layer are not included in the tri-color LED device 400.

[0299] In some embodiments, the LED light-emitting layer, such as 412, 430, and 436, comprises a plurality of sub-epitaxial layers with different compositions. Examples of LED epitaxial layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. Examples of microLEDs include GaN-based UV / blue / green microLEDs, AlInGaP-based red / orange microLEDs, and GaAs or InP-based infrared (IR) microLEDs.

[0300] In some embodiments, each LED structure in the stacked LED structure can be controlled individually to produce its own light. In some embodiments, the mixed light emitted from the top LED epitaxial layer can change the color of a single pixel within a small coverage area on the display panel due to the simultaneous operation of all LED epitaxial layers in the tri-color LED device 400.

[0301] In some embodiments, depending on the design of the LED device 400, the color of light emitted by the various LED structures included in the same device is not limited to red, green, and blue. For example, a suitable color can be selected from a range of different colors of light with wavelengths from 380 nm to 700 nm within the visible light range. In some embodiments, the LED structure can also be configured to emit other colors of light from the invisible range, such as ultraviolet and infrared light.

[0302] In some embodiments, when vertical and horizontal light emission are combined, for example, the choice of three colors from bottom to top may be red, green, and blue. In another embodiment, the choice of three colors from bottom to top may be infrared, orange, and ultraviolet light. In some embodiments, the wavelength of light emitted by the LED structure on one layer of device 400 is longer than the wavelength of light emitted by the LED structure on the layer above it. For example, the wavelength of light emitted by the bottom LED light-emitting layer 412 is longer than the wavelength of light emitted by the middle LED light-emitting layer 430, and the wavelength of light emitted by the middle LED light-emitting layer 430 is longer than the wavelength of light emitted by the top LED light-emitting layer 436.

[0303] In some embodiments, when the light emission is horizontal or when the horizontally emitting portion exceeds the vertically emitting portion from the top surface of the LED device 400, each of the LED light-emitting layers 412, 430, and 436 can be any suitable color of visible or invisible light. The advantage of horizontal light emission is that since the emitted light does not need to pass through other upper layers of the LED device 400 but is emitted directly from the edge or sidewall of the current light-emitting layer, light propagation loss can be reduced, and luminous efficiency can be improved. For example, compared to vertically emitting LED devices, horizontally emitting LED devices can improve light propagation efficiency by 15%, 50%, 100%, 150%, or 200%. In some cases, the light propagation efficiency of horizontally emitting LED devices can be equal to or greater than 20%, 40%, or 60%.

[0304] In some embodiments, the bottom red LED light-emitting layer 412 is bonded to the substrate 404 via a metal bonding layer 408. The metal bonding layer 408 may be disposed on the substrate 404. In one method, the metal bonding layer 408 is grown on the substrate 404. In some embodiments, the metal bonding layer 408 is electrically connected to the driving circuit 406 on the substrate 404 and the red LED light-emitting layer 412 above the metal bonding layer 408, serving as a P-electrode. In some embodiments, the thickness of the metal bonding layer 408 is approximately 0.1 micrometers to 3 micrometers. In a preferred embodiment, the thickness of the metal bonding layer 408 is approximately 0.3 micrometers. The metal bonding layer 408 may include an ohmic contact layer and a metal bonding layer. In some cases, the metal bonding layer 408 includes two metal layers. One of the metal layers is deposited above the metal bonding layer within the LED device 400. A corresponding bonding metal layer is also deposited on the substrate 404. In some embodiments, the composition of the metal bonding layer 408 includes Au-Au bonding, Au-Sn bonding, Au-In bonding, Ti-Ti bonding, Cu-Cu bonding, or a mixture thereof. For example, if Au-Au bonding is selected, the two Au layers require a Cr coating as a binder layer and a Pt coating as an anti-diffusion layer, respectively. The Pt coating is located between the Au layer and the Cr layer. The Cr layer and the Pt layer are located on top and bottom of the two bonded Au layers. In some embodiments, when the two Au layers are of approximately the same thickness, the Au on the two layers diffuses into each other under high pressure and high temperature, bonding the two layers together. Eutectic bonding, thermocompression bonding, and transient liquid phase (TLP) bonding are exemplary techniques that can be used.

[0305] In some embodiments, the metal bonding layer 408 may also be used as a reflector to reflect light emitted from the LED structure above.

[0306] In some embodiments, a conductive layer 410 for electrode connection is formed at the bottom of the red LED light-emitting layer 412. In some embodiments, the conductive layer 410 is a conductive transparent layer, such as an indium tin oxide (ITO) layer, that is transparent to the light emitted by the LED device 400, and is formed between the red LED light-emitting layer 412 and the metal bonding layer 408 to improve conductivity and light transmittance. Figure 4A As shown in Figure 4B In some embodiments not shown, the red LED structure has a P-electrode contact pad 450 electrically connected to the red LED light-emitting layer 412. In some embodiments, the P-electrode contact pad 450 is connected to the conductive layer 410. In some embodiments, a conductive layer 414 for electrode connection is formed on top of the red LED light-emitting layer 412. In some embodiments, the conductive layer 414 may be a conductive transparent layer such as an ITO layer, formed between the red LED light-emitting layer 412 and the N-electrode contact pad 416 to improve conductivity and light transmittance.

[0307] In some embodiments, the red LED emitting layer 412 has an extension 464 on one side relative to the other layers above it. In some embodiments, the extension 464 extends together with the conductive layers 410 and 414. In some embodiments, the extension 464 is connected to the N-electrode contact pad 416 via an extension of the conductive layer 414 above the extension 464.

[0308] In some embodiments, the reflective layer 409 is located below the red LED emitting layer 412 between the conductive layer 410 and the metal bonding layer 408, and the reflective layer 415 is located above the red LED emitting layer 412 between the conductive layer 414 and the bonding layer 456, and in one example, it is located within the planarized insulating layer 454.

[0309] In one method, the red LED light-emitting layer 412 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 4B The structure shown.

[0310] In some embodiments, the red LED emitting layer 412 is used to form a red microLED. Examples of red LED emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the red LED emitting layer 412 may comprise layers of P-type GaP / P-type AlGaInP / AlGaInP / N-type AlGaInP / N-type GaAs. In some embodiments, the P-type layer is typically Mg-doped, while the N-type layer is typically Si-doped. In some examples, the thickness of the red LED emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the red LED emitting layer is approximately 0.3 micrometers.

[0311] In some embodiments, the red LED structure includes a metal bonding layer 408, a reflective layer 409, a conductive layer 410, a red LED light-emitting layer 412, a conductive layer 414, a reflective layer 115, and an N-electrode contact pad 416. In some embodiments, the red LED structure is formed within a planarized insulating layer 454, for example, within a silicon dioxide (SiO2) layer. In some embodiments, the planarized insulating layer 454 covers the entire red LED structure. In some embodiments, the entire red LED structure is embedded within the planarized insulating layer 454. In some embodiments, the surface of the planarized insulating layer 454 is smoothed or planarized by a chemical mechanical polishing method.

[0312] In some embodiments, the planarization layer, such as 454, is transparent to light emitted by the LED device 400. In some embodiments, the planarization layer is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes SiO2, Al2O3, Si3N4, phosphosilicate glass (PSG), or borosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or Micro Resist's bonding adhesive BCL-1200, or any combination thereof. In some embodiments, the planarization layer may facilitate the passage of light emitted by the microLED 400. In some embodiments, the planarization layers, such as 454, 468, and 462, have the same composition as the bonding layers, such as 456 and 460. In some embodiments, the planarization layers, such as 454, 468, and 462, have a different composition than the bonding layers, such as 456 and 460.

[0313] In some embodiments, vias or through-holes are formed within the planarized insulating layer 454 to accommodate P-electrode contact elements 422 and 424 for a green LED structure. P-electrode contact elements 422 and 424 are connected to the drive circuit 406.

[0314] In some embodiments, bonding layer 456 is used to bond the red LED structure and the green LED structure together. In some embodiments, bonding layer 456 is opaque to light emitted by LED device 400. In some embodiments, the material and thickness of bonding layer 456 are the same as described above for metal bonding layer 408. In some embodiments, bonding layer 456 may also be used as a reflector to reflect light emitted by the upper LED structure.

[0315] In some embodiments, when vertical propagation is used, the bonding layer 456 is transparent to the light emitted by the microLED 400. In some embodiments, the bonding layer 456 is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes SiO2, Al2O3, Si3N4, phosphosilicate glass (PSG), or borosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or Micro Resist's bonding adhesive BCL-1200, or any combination thereof. In some embodiments, the transparent bonding layer allows light emitted from the layer beneath the bonding layer to pass through.

[0316] In some embodiments, a conductive layer 428 for electrode connection is formed at the bottom of the green LED light-emitting layer 430. In some embodiments, the conductive layer 428 is a conductive transparent layer 428, such as an ITO layer, formed between the green LED light-emitting layer 430 and the bonding layer 456 to improve conductivity and light transmittance.

[0317] In some embodiments, such as Figure 4A and Figure 4B As shown, the green LED structure has a P-electrode contact pad 426 electrically connected to the green LED light-emitting layer 430. In some embodiments, the P-electrode contact pad is connected to a conductive layer 428. In some embodiments, the P-electrode contact pad 426 is also connected to P-electrode contact elements 422 and 424 within a planarized insulating layer 454 via portions of the P-electrode contact pad 426 within a bonding layer 456. In some embodiments, the P-electrode contact element 422 is cylindrical. In some embodiments, the P-electrode contact element 424 is funnel-shaped, narrow at the top and wide at the bottom, the narrow top side matching the width of the component 422, the funnel shape serving to support the element 422 above it. In some embodiments, a conductive layer 432 for electrode connection is formed on top of the green LED light-emitting layer 430. In some embodiments, the conductive layer 432 is a conductive transparent layer 432, such as an ITO layer, formed between the green LED light-emitting layer 430 and the N-electrode contact pad 420 to improve conductivity and light transmittance. In some embodiments, in Figure 4A and Figure 4B As shown in the diagram, the green LED structure has an N-electrode contact pad 420 electrically connected to the green LED light-emitting layer 430. In some embodiments, the N-electrode contact pad 420 is connected to the conductive layer 432. In some embodiments, the N-electrode contact pad 420 of the green LED structure is also electrically connected to the N-electrode contact pad 416 of the red LED structure via an N-electrode contact element 418 within a transparent bonding layer 456. In some embodiments, a through-hole or via is formed within the bonding layer 456 to accommodate a portion of the N-electrode contact element 418 and the P-electrode contact pad 426.

[0318] In some embodiments, the green LED light-emitting layer 430 has an extension 466 on one side relative to the other layers above it. In some embodiments, the extension 466 extends together with the conductive layers 428 and 432. In some embodiments, the extension 466 is connected to the N-electrode contact pad 420 via an extension of the conductive layer 432 above the extension 466.

[0319] In some embodiments, the lateral dimensions of the green LED light-emitting layer 430 are approximately the same as those of the red LED light-emitting layer 412, especially for the effective light-emitting area.

[0320] In some embodiments, the reflective layer 427 is below the green LED light-emitting layer 430, located between the conductive layer 428 and the bonding layer 456, and the reflective layer 433 is above the green LED light-emitting layer 430, located between the conductive layer 432 and the bonding layer 460, and in one example, within the planarized insulating layer 458.

[0321] In one approach, the green LED light-emitting layer 430 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 4B The structure shown.

[0322] In some embodiments, the green LED light-emitting layer 430 is used to form a green microLED. Examples of green LED light-emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the green LED light-emitting layer 430 may comprise a layer of P-type GaN / InGaN light-emitting layer / N-type GaN. In some embodiments, the P-type is typically Mg-doped, while the N-type is typically Si-doped. In some examples, the thickness of the green LED light-emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the green LED light-emitting layer is approximately 0.3 micrometers.

[0323] In some embodiments, the green LED structure includes a reflective layer 427, a conductive layer 428, a green LED light-emitting layer 430, a conductive layer 432, a reflective layer 433, and an N-electrode contact pad 420. In some embodiments, the green LED structure is formed within a planarized insulating layer 458. In some embodiments, the planarized insulating layer 458 covers the entire green LED structure and a portion of the P-electrode contact pad 426. In some embodiments, the entire green LED structure is embedded within the planarized insulating layer 458. In some embodiments, both surfaces of the planarized insulating layer 458 are smoothed or planarized using a chemical mechanical polishing method.

[0324] In some embodiments, excluding extensions such as 464 and 466, the first LED structure, for example, a red LED structure, and the second LED structure, for example, a green LED structure, have the same central axis. In some embodiments, excluding extensions such as 464 and 466, the first LED structure and the second LED structure are aligned along the same central axis.

[0325] In some embodiments, bonding layer 460 is used to bond the green LED structure and the blue LED structure together. In some embodiments, bonding layer 456 is opaque to light emitted by LED device 400. In some embodiments, the material and thickness of bonding layer 460 are the same as described above for metal bonding layer 408. In some embodiments, bonding layer 460 may also function as a reflector to reflect light emitted by the LED structure above.

[0326] In some embodiments, when vertical propagation is used, the bonding layer 460 is transparent to light emitted by the LED device 400. In some embodiments, the bonding layer 460 is made of a dielectric material such as a solid inorganic material or a plastic material, as described above for the bonding layer 456. In some embodiments, a transparent bonding layer can facilitate the passage of light emitted from layers beneath the bonding layer.

[0327] In some embodiments, a conductive layer 434 for electrode connection is formed at the bottom of the blue LED light-emitting layer 436. In some embodiments, the conductive layer 434 is a conductive transparent layer 434, such as an ITO layer, formed between the blue LED light-emitting layer 436 and the bonding layer 460 to improve conductivity and light transmittance. In some embodiments, such as Figure 4A As shown, but Figure 4B Not shown, the blue LED structure has a P-electrode contact pad 452 electrically connected to the blue LED light-emitting layer 436. In some embodiments, the P-electrode contact pad 452 is connected to the conductive layer 434. In some embodiments, the P-electrode contact pad 452 is also connected to a number of P-electrode contact elements similar to 422 and 424 within the planarized insulating layers 454 and 458 and the transparent bonding layers 456 and 460. Figure 4A and 4B (None are shown in the image). Those P-electrode contact elements are connected to the drive circuit 406.

[0328] In some embodiments, a conductive layer 438 for electrode connection is formed on top of the blue LED light-emitting layer 436. In some embodiments, the conductive layer 438 is a conductive transparent layer 438, such as an ITO layer, formed between the blue LED light-emitting layer 436 and the N-electrode 440 to improve conductivity and light transmittance. In some embodiments, such as Figure 4B As shown, the N electrode 440 has N electrode contact pads 442 and 444 electrically connected to the blue LED light-emitting layer 436 via the N electrode 440 and the conductive layer 438. In some embodiments, the N electrode 440 is also electrically connected to the N electrode contact pad 420 of the green LED structure. In some embodiments, the N electrode 440 is made of a material such as graphene, ITO, AZO, or FTO, or any combination thereof.

[0329] In some embodiments, the lateral dimensions of the blue LED light-emitting layer 436 are substantially the same as those of the green LED light-emitting layer 430, particularly in terms of the effective light-emitting area.

[0330] In some embodiments, a reflective layer 435 is provided below the blue LED light-emitting layer 436 and between the conductive layer 434 and the bonding layer 460. In some embodiments, an optional reflective layer 439 is provided above the blue LED light-emitting layer 436 and on top of the conductive layer 438. Figure 4B (Not shown in the image).

[0331] In one approach, the blue LED light-emitting layer 436 is grown on a separate substrate (referred to as the epitaxial substrate). After bonding, the epitaxial substrate is removed by, for example, a laser lift-off process or wet chemical etching, leaving... Figure 4B The structure shown.

[0332] In some embodiments, the blue LED emitting layer 436 is used to form a blue microLED. Examples of blue LED emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some cases, the film within the blue LED emitting layer 436 may comprise a layer of P-type GaN / InGaN emitting layer / N-type GaN. In some embodiments, the P-type is typically Mg-doped, while the N-type is typically Si-doped. In some examples, the thickness of the blue LED emitting layer is approximately 0.1 micrometers to 5 micrometers. In a preferred embodiment, the thickness of the blue LED emitting layer is approximately 0.3 micrometers.

[0333] In some embodiments, the blue LED structure includes a reflective layer 435, a conductive layer 434, a blue LED light-emitting layer 436, a conductive layer 438, and an optional reflective layer 439. In some embodiments, the blue LED structure is formed within a planarized insulating layer 462. In some embodiments, the planarized insulating layer 462 covers the entire blue LED structure. In some embodiments, the entire blue LED structure is embedded within the planarized insulating layer 462. In some embodiments, the bottom surface of the planarized insulating layer 462 is smoothed or planarized by a chemical mechanical polishing method.

[0334] In some embodiments, through holes or vias are formed within the planarized insulating layer 462 and the transparent bonding layer 460 to accommodate portions of the N electrode 440 connected to the N electrode contact pad 420 of the green LED structure.

[0335] In some embodiments, the N-electrode 440 covers the top of the planarized insulating layer 462. In some embodiments, the N-electrode 440 covers the top of the tri-color LED device 400. In some embodiments, the N-electrode 440 is connected to the N-electrode of an adjacent tri-color LED device via N-electrode contact pads 442 and 444. Figure 4A (or not shown in 4B), which is used as the common electrode.

[0336] In some embodiments, the lateral dimensions of the blue LED structure are approximately the same as those of the green LED structure. In some embodiments, excluding extensions such as 466, the second LED structure, for example the green LED structure, and the third LED structure, for example the blue LED structure, have the same central axis. In some embodiments, excluding extensions such as 466, the second LED structure and the third LED structure are aligned along the same central axis.

[0337] In some embodiments, the thickness of each of the conductive layers 410, 414, 428, 432, 434, and 438 is approximately 0.01 micrometers to 1 micrometer. In some cases, each of the conductive layers 410, 414, 428, 432, 434, and 438 is typically deposited on its respective epitaxial layer by a vapor deposition process, such as electron beam evaporation or sputtering, prior to any bonding process with the next epitaxial layer. In some examples, the conductive layers are used to maintain good conductivity of the electrode connections, while in other cases, they are also used to improve the optical properties of the LED device, such as reflectivity or transmittance.

[0338] In some embodiments, to improve the luminous efficiency of the tri-color LED device 400, optical isolation structures such as 446 and 448 are formed along the sidewalls of the tri-color LED device 400. In some embodiments, the optical isolation structures 446 and 448 are made of a dielectric material such as SiO2.

[0339] like Figure 4AAs shown in the top view, in some embodiments, the tri-color LED device 400 has a circular shape. In some embodiments, optical isolation structures such as 446 and 448 are integrally connected and form a circular sidewall surrounding the tri-color LED device 400. In some embodiments, the optical isolation structures form a reflector cup, which is described in further detail below. In some embodiments, the three stacked LED structures within the tri-color LED device 400 are also circular in shape. In some embodiments, the tri-color LED device 400 may have other shapes, such as rectangles, squares, triangles, trapezoids, and polygons. In some embodiments, optical isolation structures such as 446 and 448 are integrally connected and form a sidewall surrounding the tri-color LED device 400 in other shapes such as rectangles, squares, triangles, trapezoids, and polygons.

[0340] like Figure 4B As shown, in some embodiments, the red LED light-emitting layer 412, the green LED light-emitting layer 430, and the blue LED light-emitting layer 436 have inclined side surfaces. As used herein, an inclined side surface can refer to a surface that is not perpendicular to the top or bottom surface of the respective LED light-emitting layer. In some embodiments, the angle between the inclined sidewall and the bottom surface of the respective LED light-emitting layer is less than 90 degrees. In some embodiments, the metal bonding layer 408 also has inclined side surfaces. These inclined side surfaces facilitate the connection of different connecting elements to the respective LED light-emitting layers, prevent the connection from breaking due to abrupt angles, and enhance the overall stability of the device.

[0341] In some embodiments, the light propagation efficiency of the multicolor LED device changes with the angle of the tilted side surface of the LED light-emitting layer relative to the normal of the substrate 404 surface. In some embodiments, the light propagation efficiency of the multicolor LED device increases with the increase of the angle of the tilted side surface of the LED light-emitting layer relative to the normal of the substrate 404 surface. For example, when the angle of the side surface of the LED light-emitting layer relative to the normal of the substrate 404 surface is ±5 degrees, and when the optical isolation structure such as 446 and / or 448 is not a reflector cup as described below, the luminous efficiency of the multicolor LED device is 0.32%. For example, when the angle of the side surface of the LED light-emitting layer relative to the surface normal of the substrate 404 is ±15 degrees, and when the optical isolation structure such as 446 and / or 448 is not a reflector cup as described below, the luminous efficiency of the multicolor LED device is 2.7%. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 404 is (e.g., when the light-emitting layer is tilted) or very close to ±90 degrees and when the optical isolation structure such as 446 and / or 448 is not a reflector cup as described below, the luminous efficiency of the multicolor LED device is equal to or very close to 56.4%.

[0342] In contrast, the implementation of the reflector structure, as described in further detail below, improves the light propagation efficiency of the multicolor LED device. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 404 is ±5 degrees and when the optical isolation structure, such as 446 and / or 448, is the reflector as described below, the luminous efficiency of the multicolor LED device is 0.65%, which is an increase of 104.6% compared to an LED device without a reflector. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 404 is ±15 degrees and when the optical isolation structure, such as 446 and / or 448, is the reflector as described below, the luminous efficiency of the multicolor LED device is 6.65%, which is an increase of 144.4% compared to an LED device without a reflector. For example, when the angle between the side surface of the LED light-emitting layer and the normal to the surface of the substrate 404 is (e.g., when the light-emitting layer is tilted) or very close to ±90 degrees and when the optical isolation structure such as 446 and / or 448 is a reflector cup as described below, the luminous efficiency of the multicolor LED device is equal to or very close to 66.65%, that is, an increase of 18.4% compared to an LED device without a reflector cup.

[0343] In some embodiments, the sizes of the red LED light-emitting layer 412, the green LED light-emitting layer 430, and the blue LED light-emitting layer 436 are similar. For example, the surface areas of the red LED light-emitting layer 412, the green LED light-emitting layer 430, and the blue LED light-emitting layer 436 are substantially the same, especially in terms of the effective light-emitting area.

[0344] In some embodiments, reflective layers are formed above and below each layer of the LED light-emitting layer to improve light propagation efficiency. For example... Figure 4B As shown, in some embodiments, a reflective layer 409 is formed between the bonding layer 408 and the red LED light-emitting layer 412. In some embodiments, when a conductive layer 410 is present, the reflective layer 409 is formed between the bonding layer 408 and the conductive layer 410. In some embodiments, a reflective layer 415 is formed between the bonding layer 456 (and / and within the planarized insulating layer 454) and the red LED light-emitting layer 412. In some embodiments, when a conductive layer 414 is present, the reflective layer 415 is formed between the bonding layer 456 (and / and within the planarized insulating layer 454) and the conductive layer 414.

[0345] In some embodiments, a reflective layer 427 is formed between the bonding layer 456 (and / and within the planarized insulating layer 458) and the green LED light-emitting layer 430. In some embodiments, when a conductive layer 428 is present, the reflective layer 427 is formed between the bonding layer 456 (and / and within the planarized insulating layer 458) and the conductive layer 428. In some embodiments, a reflective layer 433 is formed between the bonding layer 460 (and / and within the planarized insulating layer 458) and the green LED light-emitting layer 430. In some embodiments, when a conductive layer 432 is present, the reflective layer 433 is formed between the bonding layer 460 (and / / within the planarized insulating layer 458) and the conductive layer 432.

[0346] In some embodiments, a reflective layer 435 is formed between the bonding layer 460 (and / and within the planarized insulating layer 462) and the blue LED light-emitting layer 436. In some embodiments, in the presence of a conductive layer 434, the reflective layer 435 is formed between the bonding layer 460 (and / or within the planarized insulating layer 462) and the conductive layer 434. In some embodiments, an optional reflective layer 439 is formed between the N-electrode pad 440 and the blue LED light-emitting layer 436. Figure 4B (Not shown in the image), while still allowing the blue LED emitting layer 436 to be electrically connected to the N electrode pad 440, for example, via a conductive path. In some embodiments, in the presence of the conductive layer 438, an optional reflective layer 439 is formed between the N electrode pad 440 and the conductive layer 438, while still allowing the conductive layer 438 to be electrically connected to the N electrode pad 440, for example, via a conductive path.

[0347] In some embodiments, the material, composition, properties, and manufacturing process of the reflective layer are the same as those described above with respect to Figures 1-3.

[0348] In some embodiments, a tri-color LED structure is formed by dry etching and wet etching, with the axes of the different colored LED structures vertically aligned with each other. In some embodiments, the different colored LED structures share the same axis.

[0349] In some embodiments, each of the multiple LED structures of different colors is formed in a pyramidal or trapezoidal shape within its respective planarized insulating structure. Each layer has a narrower width or smaller area compared to the layer below it. In this case, the width or area is measured by the dimensions of a plane parallel to the surface of substrate 404. In some embodiments, particularly when a planarized layered structure is used, each LED structure of different colors has substantially the same lateral dimension compared to the other LED structures. When each LED structure in the LED structure has substantially the same area, the luminous efficiency of the overall LED device is improved.

[0350] In some embodiments, particularly without the use of a planarized layered structure, each LED structure in the different color LED structure is bonded together by a bonding layer that covers only the LED structure area without any extension beyond the LED structure area, and the entire multicolor LED device forms a pyramid (or inverted cone) shape or a trapezoidal cross-section (in... Figure 4B (Not shown in the image). In some embodiments, for example, the lateral dimension of the bottom LED structure in a red LED structure may be the longest, and the lateral dimension of the top LED structure in a blue LED structure may be the shortest. The pyramid shape can be naturally formed from bottom to top during the etching and patterning of the individual layers within the LED device. The pyramid structure can improve the electronic connection between individual LED structures and with electrodes, and simplify the manufacturing process. For example, electrode connection elements in each layer are exposed in each layer to facilitate connection.

[0351] In some embodiments, the bottom layer, such as the metal bonding layer 408, has a lateral dimension of about 1 micrometer to 500 micrometers. In a preferred embodiment, the lateral dimension of the metal bonding layer 408 at the bottom of the multicolor LED device is about 2.0 micrometers. In some embodiments, the vertical height of the multicolor LED device is about 1 micrometer to 500 micrometers. In a preferred embodiment, the vertical height of the multicolor LED device is about 1.9 micrometers. In a preferred embodiment, the lateral dimension of the conductive layer 438 at the top of the multicolor LED device is about 1.0 micrometer.

[0352] In some embodiments, the aspect ratio of the layers in a tri-color LED device remains substantially the same when the lateral dimensions of the same layer vary. For example, when the lateral dimension of a patterned epitaxial layer is 5 micrometers, the thickness of the patterned epitaxial layer is less than one micrometer. In another example, when the lateral dimension of the same patterned epitaxial layer increases, the thickness of the same patterned epitaxial layer increases accordingly to maintain the same aspect ratio. In some embodiments, the aspect ratio of the epitaxial layer and other layers is less than 1 / 5 of the thickness / width.

[0353] The shape of the LED device is not limited, and in some other embodiments, the cross-sectional shape of the tri-color LED device can be other shapes, such as inverted trapezoid, semi-ellipse, rectangle, parallelogram, triangle or hexagon, etc.

[0354] In some embodiments, planar insulating layers, such as 454, 458, and 462, are used to cover each LED structure in different color LED structures, simplifying the manufacturing process of a single-pixel tri-color LED device and improving its luminous efficiency. For example, each LED structure in different color LED structures can first be independently formed within a corresponding planar insulating layer, including a conductive layer, a reflective layer, and electrode contact pads, as well as their associated connectors, and then the individual LED structures are bonded together through corresponding bonding layers.

[0355] In contrast, in the manufacturing process of directly stacked tri-color LED devices without planarization features, LED structures of different colors are directly bonded together using bonding layers. A single-pixel tri-color LED device can be formed into a pyramid (or inverted cone) shape or a trapezoidal cross-section through layer-by-layer patterning (and / or etching). Therefore, the effective light-emitting area for the LED structure is largest at the bottom of the stack of a single-pixel tri-color LED device, and smallest at the top. Non-uniformity of the light-emitting areas among multiple LED structures within the LED device reduces its luminous efficiency. Although it has a planarized layered structure, a single-pixel tri-color LED device is not limited to the pyramid structure described above because each LED structure is manufactured within its own planarized insulating layer. Instead, the effective light-emitting area of ​​different LED structures within a single-pixel tri-color LED device can be adjusted according to the design. In some cases, the horizontal effective light-emitting areas of different LED structures within a single-pixel tri-color LED device are substantially the same to improve luminous efficiency and facilitate electrical interconnection. In some cases, a planarized tri-color LED structure can improve luminous efficiency by at least 5%, at least 10%, or sometimes, at least 20%, compared to a similar tri-color LED structure without planarization.

[0356] In some embodiments, when each of the LED light-emitting layers described above is grown using a corresponding epitaxial substrate, an insulating layer may first be deposited on each of the epitaxial substrate covering the corresponding LED light-emitting layer and other layers such as conductive and reflective layers. Then, a planarization process is performed to flatten the surface of the insulating layer in which the corresponding LED structure is embedded. Vias for electrical connections are also formed within the planarized layers prior to bonding.

[0357] In another embodiment, the layers of the LED structure, including the bonding layer, can be formed directly on a planarized insulating layer on which the formed LED structure is already embedded, followed by the formation of a planarized insulating layer to cover the current LED structure. Before the next LED structure is formed on top of the current LED structure, vias for electrical connections are formed within the planarized layer.

[0358] Compared to other processes where the bonding layer directly contacts the top or bottom of the LED structure to form the device, without a planarized insulating layer, the bonding layer can contact the planarized insulating layer without touching the LED structure. Therefore, the features and layers within each planarized LED structure are better protected and less susceptible to external destructive forces. Furthermore, the planarized surface can improve light propagation efficiency by reducing deflection caused by uneven surfaces.

[0359] In some embodiments, the top conductive layer 438 above the third LED light-emitting layer 436 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is, for example, dry etching such as inductively coupled plasma (ICP) etching or wet etching with an ITO etching solution. In some embodiments, the same patterning method can be applied to all other conductive layers within the tri-color LED device 400, including layers 410, 414, 428, 432, 434, and 438.

[0360] In some embodiments, the blue LED light-emitting layer 436 and the green LED light-emitting layer 430 are patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using Cl2 and BC13 etching gases.

[0361] In some embodiments, the bonding layers including 460 and 456 are patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases.

[0362] In some embodiments, the reflective layers including 409, 415, 427, 433, 435, and 439 are patterned using photolithography and etching. In some cases, the etching method used to form the patterned reflective layers, particularly the DBR layers, is dry etching, such as inductively coupled plasma (ICP) etching using CF4 and O2 etching gases or ion beam etching (IBE) using Ar gas.

[0363] In some embodiments, the red LED light-emitting layer 412 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using Cl2 and HBr etching gases.

[0364] In some embodiments, the metal bonding layer 408 is patterned using photolithography and etching. In some cases, the etching method used to form the pattern is dry etching, such as inductively coupled plasma (ICP) etching using C12 / BC13 / Ar etching gases, or ion beam etching (IBE) using Ar gas.

[0365] In some embodiments, after each LED device structure in each LED device structure is patterned, an insulating layer such as 454, 458, or 462 is deposited on the surface of each patterned LED structure, including all patterned layers, sidewalls, and exposed substrate. In some embodiments, the insulating layer is made of SiO2 and / or Si3N4. In some embodiments, the insulating layer is made of TiO2. In some embodiments, an insulating layer having a composition similar to SiO2 is formed after a layer such as SOG is cured at a high temperature. In some embodiments, the insulating layer is made of a material having a thermal coefficient similar to that of the layers below it. The surface of the insulating layer is then smoothed or planarized by methods such as chemical mechanical polishing, as understood by those skilled in the art.

[0366] In some embodiments, the planarized insulating layer is patterned using photolithography and etching to expose the electrode contact areas. In some cases, the etching method used to form the pattern is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2.

[0367] In some embodiments, the P-electrode or anode metal pad is deposited at appropriate locations on the patterned LED structure, such as on one side within a planarized insulating layer and / or in a via, using vapor deposition or other deposition methods, to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0368] In some embodiments, individual N-electrodes or cathode metal pads are deposited using vapor deposition or other deposition methods at appropriate locations on the patterned LED structure, such as on one side / top and / or in vias within a planarized insulating layer, to electrically connect the red LED structure, green LED structure, and blue LED structure.

[0369] Figure 5 It is a single-pixel tri-color LED device 500 with a refractive structure according to some embodiments. Figure 1A A cross-sectional view of the middle diagonal 102. In some embodiments, although not all Figure 5As shown, the single-pixel tri-color LED device 500 has a structure similar to any of the single-pixel tri-color LED devices shown in Figures 1-4, but with the addition of a refractive structure 502 formed above the top surface of the single-pixel tri-color LED device to improve luminous efficiency. Light emitted by the single-pixel tri-color LED device is emitted through the top surface of the single-pixel tri-color LED device without the refractive structure (light-emitting region). In some embodiments, the top surface of the refractive structure 502 is planarized. In some embodiments, the refractive structure 502 covers and contacts the exposed surface of a top electrode, such as the N-electrode 140. In some embodiments, the refractive structure 502 is formed directly on the surface of the planarized insulating layer 176. In some embodiments, the refractive structure 502 is identical to and integrated with the planarized insulating layer 176.

[0370] In some embodiments, a refractive structure 502 is formed between an optical isolation structure, such as reflectors 146 and 148, and the top surface of a single-pixel tri-color LED device without a refractive structure, i.e., the light-emitting region. In some embodiments, the top surface of the refractive structure 502 is above the top of the optical isolation structure. In some embodiments, the top surface of the refractive structure 502 is at the same height as the top of the optical isolation structure or below the top of the optical isolation structure. In some embodiments, the top surface of the refractive structure is above a top electrode, such as the N-electrode 140. In some embodiments, the top surface of the refractive structure is at the same height as the top electrode, such as the N-electrode 140, or below the top electrode.

[0371] In some embodiments, the refractive structure 502 alters the light path of the light emitted by a single pixel tri-color LED device by making the light emitted by the LED device more focused or more diffused, as required by the design.

[0372] In some embodiments, the refractive layer 502 is made of a dielectric material. In some embodiments, the dielectric material is transparent to the light emitted by a single pixel tri-color LED device, such as silicon oxide, silicon nitride, silicon carbide, titanium oxide, zirconium oxide, aluminum oxide, etc. In some embodiments, the dielectric material is selected from one or more polymers such as SU-8, photosensitive polyimide (PSPI), BCB, etc.

[0373] In some embodiments, the refractive layer 502 is formed directly over the planarized insulating layer. In some embodiments, the refractive layer 502 is formed by deposition, sputtering, or other methods.

[0374] Figure 6A It is a single-pixel tri-color LED device 600 with microlenses on a reflective structure according to some embodiments. Figure 1A Cross-sectional view of the middle diagonal 102.

[0375] Figure 6B It is according to some embodiments a single-pixel tri-color LED device 600 having microlenses in a region formed by a reflective structure along its edge. Figure 1A Cross-sectional view of the middle diagonal 102.

[0376] In some embodiments, although not all of them Figures 6A-6B As shown, however, the single-pixel tri-color LED device 600 has a structure similar to any of the single-pixel tri-color LED devices shown in Figures 1-5, and adds a microlens 602 formed above the top surface of the single-pixel tri-color LED device to improve luminous efficiency. Without this microlens structure (light-emitting region), the light emitted by the single-pixel tri-color LED device passes through the top surface of the single-pixel tri-color LED device. In some embodiments, the microlens 602 is formed directly on the surface of the planarized insulating layer 176. In some embodiments, the microlens 602 is formed directly on, such as... Figure 5 The refractive structure 502 shown is on the surface. In some embodiments, the microlens 602 covers and contacts the exposed surface of the top electrode, such as the N electrode 140.

[0377] In some embodiments, an optional spacer 604 is formed on top of the light-emitting region at the bottom of the microlens 602. In some embodiments, the top surface of the spacer 604 is planarized. In some embodiments, the spacer 604 is formed directly on the surface of the planarized insulating layer 176. In some embodiments, the spacer 604 is formed directly on, such as... Figure 5 On the surface of the refractive structure 502 shown. In some embodiments, the spacer 604 and, as shown... Figure 5 The refractive structure 502 shown is identical and integrated with it. In some embodiments, the spacer 604 covers and contacts the exposed surface of the top electrode, such as the N electrode 140. In some embodiments, the spacer 604 is integrated with the microlens 602. In some embodiments, the spacer 604 is identical to and integrated with the planarized insulating layer 176.

[0378] In some embodiments, microlens 602 is formed between each optical isolation structure of a reflective structure or reflector cup, such as 146 and 148, and the top surface of a single-pixel tri-color LED device that does not have a microlens, i.e., a light-emitting region, between the optical isolation structures. In some embodiments, the top surface of microlens 602 is located above the top of the optical isolation structure, such as... Figure 6AAs shown. When the top surface of microlens 602 is positioned above the top of reflective structures such as 146 and 148, microlens 602 can essentially capture and focus all the light emitted by the individual pixel tri-color LED devices, including the reflector cup. In some embodiments, the top surface of microlens 602 is aligned with, for example, Figure 6B The top of the optical isolation structure shown is at the same height or below the top of the optical isolation structure. When the top surface of the microlens 602 is at the same level as or below the top of the reflective structure such as 146 and 148, at least a portion of the light emitted by the microlens 602 is further confined within a region of the reflective structure or reflector cup for reflection.

[0379] In some embodiments, the lateral dimension of the bottom of the microlens 602 is smaller than the lateral dimension of the light emitting region. In some embodiments, the lateral dimension of the bottom of the microlens 602 is the same as or larger than the lateral dimension of the light emitting region. In some embodiments, the lateral dimension of the bottom of the microlens 602 is smaller than the lateral dimension of the top surface region of the top light-emitting layer 136. In some embodiments, the lateral dimension of the bottom of the microlens 602 is the same as or larger than the lateral dimension of the top surface region of the top light-emitting layer 136.

[0380] In some embodiments, an optional spacer 604 is formed between an optical isolation structure, such as reflectors 146 and 148, and the top surface of a single-pixel tri-color LED device that does not have a microlens and spacer, i.e., a light-emitting region. In some embodiments, the top surface of spacer 604 is located above the top of the optical isolation structure. In some embodiments, the top surface of spacer 604 is at the same height as or below the top of the optical isolation structure. In some embodiments, the top surface of spacer 604 is located above a top electrode, such as N-electrode 140. In some embodiments, the top surface of spacer 604 is at the same height as or below the top electrode, such as N-electrode 140. In some embodiments, the lateral dimension of the bottom of microlens 602 is smaller than the lateral dimension of the top surface of spacer 604. In some embodiments, the lateral dimension of the bottom of microlens 602 is the same as or larger than the lateral dimension of the top surface of spacer 604.

[0381] In some embodiments, the microlens 602 alters the light path emitted by the individual pixel tri-color LED device by making the light emitted by the individual pixel tri-color LED device more focused or more diffused, as required by design.

[0382] In some embodiments, spacer 604 extends the optical path of light emitted by a single pixel tri-color LED device. In some embodiments, spacer 604 alters the optical path of light emitted by a single pixel tri-color LED device by making the light emitted by the single pixel tri-color LED device more focused or more diffused, as required by design.

[0383] In some embodiments, the microlens 602 may be made of various materials that are transparent to light of each wavelength emitted by a single pixel tri-color LED device. Exemplary transparent materials for the microlens 602 include polymers, dielectrics, and semiconductors. In some embodiments, the dielectric material includes one or more materials such as silicon oxide, silicon nitride, silicon carbide, titanium oxide, zirconium oxide, aluminum oxide, etc. In some embodiments, the microlens 602 is made of photoresist.

[0384] Spacer 604 is a formed optically transparent layer used to maintain the position of the microlens 602 relative to a pixel light source, such as a single-pixel tri-color LED device, below the microlens 602. Spacer 604 can be made of various materials that are transparent to light of each wavelength emitted by the pixel light source. Exemplary transparent materials for spacer 604 include polymers, dielectrics, and semiconductors. In some embodiments, the dielectric material includes one or more materials such as silicon oxide, silicon nitride, silicon carbide, titanium oxide, zirconium oxide, aluminum oxide, etc. In some embodiments, spacer 604 is made of photoresist. In some embodiments, spacer 604 and microlens 602 have the same material. In some embodiments, spacer 604 and microlens 602 have different materials.

[0385] In some embodiments, the height of the microlens 602 is no greater than 2 micrometers. In some embodiments, the height of the microlens 602 is no greater than 1 micrometer. In some embodiments, the height of the microlens 602 is no greater than 0.5 micrometers. In some embodiments, the width of the microlens 602 is no greater than 4 micrometers. In some embodiments, the width of the microlens 602 is no greater than 3 micrometers. In some embodiments, the width of the microlens 602 is no greater than 2 micrometers. In some embodiments, the width of the microlens 602 is no greater than 1 micrometer. In some embodiments, the width-to-height ratio of the microlens 602 is greater than 2.

[0386] In some embodiments, the microlens 602 is generally hemispherical in shape. In some embodiments, the central axis of the microlens 602 is aligned with or the same as the central axis of a lensless single-pixel tri-color LED device.

[0387] For clarity, Figures 6A-6BIn some embodiments, each pixel light source, such as a tri-color LED device, corresponds to a microlens 602 in a display panel. It should be understood that a complete display panel comprises an array of many individual pixels and many microlenses. Furthermore, a one-to-one correspondence between microlenses and pixel light sources is not necessarily required, nor is a one-to-one correspondence between pixel driving circuitry (not shown) and pixel light sources. Pixel light sources can also be made of multiple individual light elements, such as multiple individual pixel LEDs connected in parallel. In some embodiments, a microlens 602 can cover multiple lensless individual pixel tri-color LED devices.

[0388] Each microlens 602 has positive optical power and is configured to reduce the divergence or viewing angle of the light emitted by the corresponding pixel light source. In one example, the beam emitted by the pixel light source has a fairly wide original divergence angle. In one embodiment, the original angle of the edge rays of the beam relative to the vertical axis perpendicular to the substrate 104 is greater than 60 degrees. The light is bent by the microlens 602, such that the new edge rays now have a reduced divergence angle. In one embodiment, the reduced angle is less than 30 degrees. The microlenses in the microlens array are typically identical. Examples of microlenses include spherical microlenses, aspherical microlenses, Fresnel microlenses, and cylindrical microlenses.

[0389] Microlens 602 typically has a planar side and a curved side. In Figure 6, the bottom of microlens 602 is the planar side, and the top of microlens 602 is the curved side. Typical shapes of the base of each microlens 602 include circular, square, rectangular, and hexagonal. Individual microlenses in the microlens array of a display panel may be the same or different in terms of shape, curvature, optical power, size, base, and spacing. In some embodiments, microlens 602 conforms to the shape of a single pixel tri-color LED device. In one example, the shape of the base of microlens 602 is the same as the shape of a single pixel tri-color LED device, for example in... Figures 6A-6B In this example, they are all circular. In another example, the shape of the base of the microlens 602 differs from the shape of the individual pixel tri-color LED device. For example, the circular base of the microlens has the same width as the individual pixel tri-color LED, but a smaller area, because the base of the microlens is circular, while the base of the individual pixel tri-color LED is square. In some embodiments, the area of ​​the microlens base is smaller than the area of ​​the pixel light source. In some embodiments, the area of ​​the microlens base is the same as or larger than the area of ​​the pixel light source.

[0390] In some embodiments, when forming the microlens 602, the spacer layer 604 may be formed with the microlens 602 using the same process and the same material. In some embodiments, the height of the pixel light source, measured from the bottom of the substrate 104, is greater than, equal to, or less than the thickness of the spacer 604.

[0391] The thickness of the spacer 604 is designed to maintain an appropriate spacing between the microlens 604 and the pixel light source. As an example, for a spacer that maintains an optical spacing between the pixel light source and the microlens greater than the focal length of the microlens, an image of a single pixel is formed at a certain distance. As another example, for an optical spacer that maintains an optical spacing between the pixel light source and the microlens less than the focal length of the microlens, a reduced divergence / viewing angle is achieved. The amount of reduction in divergence / viewing angle also depends in part on the thickness of the spacer 604 measured from the top surface of the pixel light source. In some embodiments, the thickness of the spacer 604 measured from the top surface of the pixel light source is no greater than 1 micrometer. In some embodiments, the thickness of the spacer 604 measured from the top surface of the pixel light source is no greater than 0.5 micrometers. In some embodiments, the thickness of the spacer 604 measured from the top surface of the pixel light source is no greater than 0.2 micrometers. In some embodiments, the thickness of the spacer 604 measured from the top surface of the pixel light source is approximately 1 micrometer.

[0392] In some embodiments, brightness enhancement is achieved by integrating a microlens array onto the display panel. In some examples, due to the light-focusing effect of the microlenses, the brightness with a microlens array is four times that without a microlens array in a direction perpendicular to the display surface. In alternative embodiments, the brightness enhancement factor can vary depending on the design of the microlens array and optical spacers. For example, a factor greater than 8 can be achieved.

[0393] In some embodiments, a first method for manufacturing a microlens includes the step of directly depositing a microlens material layer on top of a pixel light source and making the microlens material layer in direct physical contact with the pixel light source. In some embodiments, the shape of the microlens material layer conforms to the shape of the pixel light source and forms a hemisphere on the pixel light source. In some embodiments, the top of the pixel light source is generally flat, and the formed microlens 602 is generally hemispherical. In some embodiments, the microlens material layer is directly deposited on the surface of the pixel light source, such as the planarized surface of a single-pixel tri-color LED device, using chemical vapor deposition (CVD) technology. In some embodiments, the deposition parameters for the CVD process are: power approximately 0W to 1000W, pressure approximately 100 mTorr to 2000 mTorr, temperature approximately 23°C to 500°C, gas flow approximately 0 to 3000 sccm (standard cubic centimeters / minute), and time approximately 1 hour to 3 hours. In some embodiments, the material of the microlens material layer is a dielectric material such as silicon dioxide.

[0394] In some embodiments, the first method for manufacturing a microlens further includes the step of patterning a microlens material layer to expose an electrode region of a substrate. In some embodiments, the step of patterning the microlens material layer includes an etching step. In some embodiments, the etching step includes the step of forming a mask on the surface of the microlens material. The etching step further includes patterning the mask using a photolithography process to form an opening in the mask and expose the microlens material layer above the electrode region of the pixel light source. The etching step further includes the step of etching the portion of the microlens material layer exposed by the opening protected by the mask. In some embodiments, the exposed microlens material layer is etched using a wet etching method.

[0395] In some embodiments, a second method for manufacturing a microlens may further include an optional step of forming a marker layer with markings for alignment with a microlens material layer deposited in subsequent steps. For example, the formed marker layer aligns the units of the luminescent pixels with the microlens material layer to form a microlens at the center of the pixel light source. In some embodiments, the formed marker layer aligns the pixel light source with layers above it, particularly the microlens material layer, to form a microlens on top of the pixel light source.

[0396] A second method for manufacturing microlenses also includes the step of directly depositing a layer of microlens material on top of at least one pixel light source. Figures 6C-6D Further illustrated is a method for manufacturing a display panel with an integrated microlens array using top-down pattern transfer, according to some embodiments. In some embodiments, such as Figure 6C As shown, a microlens material layer 645 covers the top of the pixel light source 606M, and the top surface of the microlens material layer 645 is flat. In some embodiments, the microlens material layer 645 is deposited by spin-coating onto the top of the pixel light source array 606. In some embodiments, the material of the microlens material layer 645 is photoresist. In some embodiments, the material of the microlens material layer 645 is a dielectric material such as silicon oxide.

[0397] A second method for manufacturing microlenses also includes top-down patterning of microlens material layers, thereby... Figures 6C-6D The step of forming at least one hemisphere in the microlens material layer is illustrated. In some embodiments, the patterning step does not need to penetrate or etch to the bottom of the microlens material layer 645. In some embodiments, the hemisphere of the microlens 620 is positioned above at least one pixel light source 606M.

[0398] In some embodiments, the step of patterning the microlens material layer from top to bottom further includes, for example, Figure 6C The first step shown is depositing a mask layer 630 on the surface of the microlens material layer 645.

[0399] The top-down patterning of the microlens material layer further includes a second step of patterning the mask layer 630 to form a hemispherical pattern in the mask layer 630. In some examples, the mask layer 630 is first patterned by a photolithography process and then by a reflow process. In some embodiments, the photosensitive polymer mask layer 630 is patterned into discrete units 640, as shown in... Figure 6C The dashed rectangular units in the diagram are prepared for the formation of a hemispherical pattern. As an example, separate units 640 are patterned and formed using a photolithography process. The patterned photosensitive polymer mask layer 650 with the separate units 640 is then formed into a hemispherical pattern 660 via a high-temperature reflow process. In one method, the separate units 640 are formed into a separate hemispherical pattern 660 via high-temperature reflow. In some embodiments, the hemispherical pattern 660 of a single pixel does not directly physically contact the hemispherical patterns of adjacent pixels. In some embodiments, the hemispherical pattern 660 of a single pixel only contacts the hemispherical patterns of adjacent pixels at the bottom of the hemispherical pattern 660. The patterned photosensitive polymer mask layer 650 is heated to a temperature above the melting point of the polymer material for a certain period of time. After the polymer material melts to a liquefied state, the surface tension of the liquefied material causes it to take on a shape with a smooth curved surface. For a unit with a circular base of radius R, the hemispherical shape / pattern will be formed after the reflow process when the unit height is 2R / 3. Figure 6C A display panel is shown with an array of hemispherical patterns 660 integrated after a high-temperature reflow process. In some embodiments, the hemispherical patterns in the mask layer can be formed by other manufacturing methods, including the manufacturing method for microlenses described in the first method for manufacturing microlenses. In some other embodiments, the hemispherical patterns in the mask layer can be formed using grayscale mask photolithography exposure. In some other embodiments, the hemispherical patterns in the mask layer can be formed via a molding / imprinting process.

[0400] The top-down patterning of the microlens material layer also includes a third step of using the hemispherical pattern 660 as a mask to etch the microlens material layer 645 to form hemispheres in the microlens material layer 645. In some examples, the etching of the microlens material layer 645 is performed by a photolithography process. In some examples, the etching of the microlens material layer 645 is performed by, for example... Figure 6C Dry etching, such as plasma etching process 635, is shown. In some embodiments, after the microlens material layer 645 is etched, it is not etched through to expose the top surface of the pixel light source 606M, as shown. Figures 6C-6D As shown, spacers 670 are thus formed on top of or covering the top of the pixel light source 606M, such as... Figure 6D As shown.

[0401] A second method for manufacturing microlenses also includes patterning a layer of microlens material to expose electrode regions of a substrate (in... Figure 6D (Not shown in the image). In some embodiments, the step of patterning the microlens material layer includes an etching step. In some embodiments, the etching step includes forming a mask on the surface of the microlens material. The etching step further includes patterning the mask using a photolithography process to form an opening in the mask, exposing the microlens material layer above the electrode region of the pixel light source. The etching step further includes etching the exposed microlens material layer protected by the mask. In some embodiments, the exposed microlens material layer is etched using a wet etching method. In some embodiments, the opening for the electrode is located outside the display array region.

[0402] As mentioned above, Figures 6A to 6D Various manufacturing methods are illustrated to form display panels with integrated microlens arrays. It should be understood that these are merely examples, and other manufacturing techniques may also be used.

[0403] While the detailed description includes many details, these should not be construed as limiting the scope of the invention, but merely as illustrating different examples and aspects of the invention. It should be understood that the scope of the invention includes other embodiments not discussed in detail above. For example, microlenses with bases of different shapes, such as square bases or other polygonal bases, may also be used.

[0404] Figure 7 According to some embodiments, the three single-pixel tri-color LED devices 710, 720, and 730 located on substrate 104 are along... Figure 1A Cross-sectional view 700, such as 102, along the diagonal. In some embodiments, although not all Figure 7 As shown, each of the single-pixel tri-color LED devices 710, 720, and 730 has a structure similar to any of the single-pixel tri-color LED devices shown in Figures 1-6. The cross-sectional view of the single-pixel tri-color LED device 710 within rectangle 750 is equivalent to the cross-sectional view shown in any of the figures in Figures 1-6 as described above.

[0405] In some embodiments, as shown in any of the embodiments in Figures 1-7, the single-pixel tri-color LED device further includes one or more reflective cup structures, such as 702, 704, and 706. Reflective structures, such as 702, 704, and 706, surround the respective single-pixel tri-color LED devices 710, 720, and 730. The reflective cups may be formed on the semiconductor substrate 104 and configured to surround a light-emitting region in which light emitted by the single-pixel tri-color LED is emitted. For example, as... Figure 1A-1C As shown, according to Figure 1B A cross-sectional view along direction 102, and according to Figure 1C In a cross-sectional view along the 150° direction, the reflector cup may include four reflector cup portions 146, 148, 170, and 172. In some embodiments, reflector cup portions 146, 148, 170, and 172 may be formed on the semiconductor substrate 104 and positioned around the light-emitting region. In some embodiments, the reflector cup may isolate at least some or substantially all of the light emitted from the light-emitting region. For example, as shown in FIG1B-1C, when the height of the reflector cup is higher than the height of the light-emitting region, reflector cup portions 146, 148, 170, and 172 may isolate at least some or substantially all of the light emitted from the light-emitting region. Therefore, the reflector cup may suppress inter-pixel optical crosstalk and improve the overall contrast of the LED display. Reflection in the reflector cup also increases luminous efficiency and brightness by focusing the light emission in a specific direction.

[0406] In some embodiments, the height of the reflector cup may be greater than the height of the bottom LED structure, such as a red LED structure, greater than the height of the middle LED structure, such as a green LED structure, or greater than the height of the top LED structure, such as a blue LED structure. In some embodiments, the total height of the reflector cup may be greater than the combined height of the bottom LED structure, such as a red LED structure, the middle LED structure, such as a green LED structure, and the top LED structure, such as a blue LED structure. In some embodiments, the total height of the reflector cup may be greater than the height of a single pixel tri-color LED device without planarized layers. In some embodiments, the height of the reflector cup is between 0.5 micrometers and 50 micrometers. In some embodiments, the height of the reflector cup is between 1 micrometer and 20 micrometers. In some embodiments, the height of the reflector cup is between 2 micrometers and 10 micrometers. In a preferred embodiment, the height of the reflector cup is approximately 2.5 micrometers, while the height of a single pixel tri-color LED device without planarized layers is approximately 1.9 micrometers. However, in some embodiments, reflector cup portions 146, 148, 170, and 172 may have different heights. In some embodiments, the cross-section of the reflector cup portion, such as 146 or 148, is triangular. In some embodiments, the cross-section of the reflector cup portion, such as 146 or 148, is a trapezoid with a base side longer than the top side. In some embodiments, the bottom width of the reflector cup portion, such as 146 or 148, is between 0.3 micrometers and 50 micrometers. In some embodiments, the bottom width of the reflector cup portion, such as 146 or 148, is between 0.5 micrometers and 25 micrometers. In a preferred embodiment, the bottom width of the reflector cup portion, such as 146 or 148, is approximately 1 micrometer. In some embodiments, the distance from the nearest edge of the bottom of the reflector cup portion, such as 146 or 148, to the nearest edge of the bottom of the individual pixel tri-color LED device is between 0.2 micrometers and 30 micrometers. In some embodiments, the distance from the nearest edge of the bottom of the reflector cup portion, such as 146 or 148, to the nearest edge of the bottom of the individual pixel tri-color LED device is between 0.4 micrometers and 10 micrometers. In a preferred embodiment, the distance from the nearest edge of the bottom of the reflector cup portion, such as 146 / 446 or 148 / 448, to the nearest edge of the bottom of the individual pixel tri-color LED device, is... Figure 4B The distance between the P-electrode connection structures 422 shown is approximately 0.6 micrometers.

[0407] In some embodiments, the distance between the centers of adjacent reflector portions, such as 146 / 446 and 148 / 448, in a single pixel tri-color LED device is between 1 micrometer and 50 micrometers. In a preferred embodiment, the distance between the centers of adjacent reflector portions, such as 146 and 148, in a single pixel tri-color LED device is approximately 5 micrometers.

[0408] In some embodiments, a divergence angle of 0° can correspond to light propagation perpendicular to the top surface of the light-emitting region, and a divergence angle of 90° can correspond to light propagation parallel to the top surface of the light-emitting region. Changing the geometry of the reflector cup can control the divergence angle of the light emitted by the light-emitting region. Therefore, the reflector cup can reduce the divergence of the light emitted by the light-emitting region and enhance the brightness of a single pixel multicolor LED device. In some embodiments, such as Figure 1B-1C The sidewalls 146-1, 148-1, 170-1, and 172-1 of the reflector cups shown can be straight, curved, wavy, multi-lined, or a combination thereof. In some embodiments, the steepness of the sidewalls of the reflector cup portions 146, 148, 170, and 172 can be designed to reduce the divergence of light emitted from the light-emitting area. For example, the angle of the sidewalls of the reflector cup portions 146, 148, 170, and 172 relative to the vertical axis perpendicular to the substrate 104 can range from a minimum of 15 degrees to a maximum of 75 degrees. The angle of the sidewalls of the reflector cup portions 146, 148, 170, and 172 relative to the vertical axis perpendicular to the substrate 104 can range from a minimum of 5 degrees to a maximum of 60 degrees. In some preferred embodiments, the angle of the sidewalls of the reflector cup portions 146, 148, 170, and 172 relative to the vertical axis perpendicular to the substrate 104 can range from a minimum of 10 degrees to a maximum of 50 degrees. The reflector cups can also reflect some of the light emitted from the light-emitting area upwards. For example, some of the light emitted by the light-emitting area can reach reflector cups 146, 148, 170 and 172 and be reflected upwards through them.

[0409] In some embodiments, the reflector may include a metal. In some embodiments, the reflector may include a dielectric material such as silicon oxide. In some embodiments, the reflector may include a photosensitive dielectric material. In some embodiments, the photosensitive dielectric material may include SU-8, photosensitive polyimide (PSPI), or BCB. In other embodiments, the reflector may include photoresist.

[0410] In some embodiments, the reflector cup can be manufactured by a combination of deposition, photolithography, and etching processes. In some embodiments, the reflector cup can be manufactured by other suitable methods. In one method, PSPI forms the reflector cup shape using a photolithography process. Then, a metal layer with high reflectivity, including one or more metals such as Pt, Rh, Al, Au, and Ag, a stacked DBR layer including TiO2 / SiO2 layers, any other layer with total reflectivity including a multilayer omnidirectional reflector (ODR), or a combination thereof, is formed by vapor deposition on the entire surface of the multicolor LED device, which includes the reflector cup as a reflective layer. Next, the reflective layer is masked by photoresist in one region of the reflector cup, while the reflective layer in another region is etched to expose the light-emitting area.

[0411] In another method, a thicker isolation layer, including one or more of SiO2, silicon nitride, or SU8, is deposited or spin-coated onto the stacked LED structure. Then, using photoresist as a mask, the isolation layer is etched and shaped into a reflector cup. Next, a metal layer with high reflectivity, including one or more metals such as Pt, Rh, Al, Au, and Ag, a stacked DBR layer including a TiO2 / SiO2 layer, any other layer with total reflectivity including a multilayer omnidirectional reflector (ODR), or a combination thereof, is formed by vapor deposition on the entire surface of the multicolor LED device, including the reflector cup as a reflective layer. Finally, the reflective layer is masked by photoresist in the reflector cup region, while the reflective layer in another region is etched, exposing the light-emitting region.

[0412] In some embodiments, as shown in Figures 2-6, the single-pixel tri-color LED device further includes one or more top electrodes (e.g., top electrodes 140 / 440, 442, and 444) integrated with a reflector. The one or more top electrodes may be electrically connected to the top electrode (layer) 140 / 440. For example, as... Figure 4B As shown, electrodes 442 and 444 can be integrated with reflectors, such as reflector portions 446 and 448, respectively. Both top electrodes 442 and 444 can extend toward the light-emitting area and be electrically connected to the top electrodes (layers) 140 / 440. By employing one or more top electrodes, the reflector can serve as a common P-electrode or N-electrode for a single-pixel tri-color LED device. For example, when the top electrodes (layers) 140 / 440 are electrically connected to an LED structure (e.g., an LED structure including light-emitting layers 112 / 412, 130 / 430, and 136 / 436) and optionally, top electrodes 442 and 444, the reflector can serve as a common P-electrode or common N-electrode for a single-pixel tri-color LED device.

[0413] In some embodiments, the reflector cup further includes one or more reflective coatings. The one or more reflective coatings may be disposed on one or more sidewalls of the reflector cup, for example, on sidewalls 146-1, 148-1, 170-1, and 172-1. The bottom of each layer of the one or more reflective coatings does not contact the individual LED structures, such as red, green, and blue LED structures. The one or more reflective coatings can reflect light emitted from the light-emitting area, thus improving the brightness and luminous efficiency of the micro-LED panel or display. For example, light emitted from the light-emitting area can reach the one or more reflective coatings and be reflected upwards through them.

[0414] The one or more reflective coatings, together with the reflector, can utilize the reflection direction and / or intensity of light emitted from the luminous area. For example, the sidewalls 146-1, 148-1, 170-1, and 172-1 of the reflector are inclined at a certain angle, so the one or more reflective coatings disposed on the sidewalls 146-1, 148-1, 170-1, and 172-1 of the reflector are inclined at the same angle as the sidewalls 146-1, 148-1, 170-1, and 172-1 of the reflector. When light emitted from the luminous area reaches the one or more reflective coatings, the light emitted from the luminous area is reflected by the one or more reflective coatings according to the angles of the sidewalls 146-1, 148-1, 170-1, and 172-1 of the reflector.

[0415] The material of the one or more reflective coatings can be highly reflective, having a reflectivity greater than 60%, 70%, or 80%, thus reflecting most of the light emitted from the luminescent region. In some embodiments, the one or more reflective coatings may include one or more metallic conductive materials with high reflectivity. In these embodiments, the one or more metallic conductive materials may include one or more of aluminum, gold, or silver. In other embodiments, the one or more reflective coatings may be multilayered. More specifically, the one or more reflective coatings may include one or more stacked reflective material layers and one or more dielectric material layers. For example, the one or more reflective coatings may include one reflective material layer and one dielectric material layer. In other embodiments, the one or more reflective coatings may include two reflective material layers and a dielectric material layer located between the two reflective material layers. However, in some other embodiments, the one or more reflective coatings may include two dielectric material layers and a reflective material layer located between the two dielectric material layers. In some embodiments, the multilayer structure may include two or more metal layers, which may include one or more of TiAu, CrAl, or TiWAg.

[0416] In some embodiments, the one or more reflective coatings may be multilayer omnidirectional reflectors (ODRs), including a metal layer and a transparent conductive oxide (TCO) layer. For example, the multilayer structure may include a dielectric material layer, a metal layer, and a TCO layer. In some embodiments, the one or more reflective coatings may include two or more dielectric material layers, alternately arranged to form a distributed Bragg reflector (DBR). For example, the one or more reflective coatings may include a dielectric material layer, a metal layer, and a transparent dielectric layer. The transparent dielectric layer may include one or more of SiO2, Si3N4, Al2O3, or TiO2. The one or more reflective coatings may further include a dielectric material layer, a TCO, and a DBR. In other embodiments, the one or more reflective coatings may include one or more metallic conductive materials with high reflectivity. In these embodiments, the one or more metallic conductive materials may include one or more of aluminum, gold, or silver. In some embodiments, the reflective coating may have the same composition, structure, and manufacturing process as the reflective layers such as 109, 115, 127, and 133 above and below the light-emitting layer as described above.

[0417] In some embodiments, the one or more reflective coatings may be conductive, and may also function as electrical contacts with a single-pixel multicolor LED device. For example, the top electrode (layer) 140 may be electrically connected to the one or more reflective coatings. As another example, the one or more reflective coatings may be electrically connected to the one or more transparent electrode contact layers 114, 132, and 138. The one or more reflective coatings may be patterned to not block light emitted from the light-emitting area. The one or more reflective coatings may also serve as common electrodes for the LED structure within the single-pixel multicolor LED device and / or for LEDs on the display panel.

[0418] In some embodiments, a top conductive layer for connection with electrodes is formed on top of the multicolor LED device, and the top conductive layer is electrically connected to the reflector. In some embodiments, the top conductive layer is in direct contact with the top or bottom of the reflector.

[0419] In some embodiments, a bottom dielectric layer is formed between the bottom of the reflector and the semiconductor substrate.

[0420] In some embodiments, the one or more reflective coatings may be manufactured by one or more of electron beam deposition or sputtering processes.

[0421] In some embodiments, the reflector cup may have a stepped structure. Figure 8 It is a single-pixel tri-color LED device 800 with a stepped reflector cup according to some embodiments. Figure 4AA cross-sectional view of the diagonal, such as 402. In some embodiments, although not all Figure 8 As shown, the single-pixel tri-color LED device 800 has a structure similar to any of the single-pixel tri-color LED devices shown in Figures 1-7, having reflector portions such as 146, 148, 170, and 172, and has a stepped reflector. This stepped reflector can be formed on the semiconductor substrate 104 / 404 and positioned around the light-emitting area. For example, as... Figure 8 As shown, according to along Figure 4A A cross-sectional view along the diagonal of substrate 104 / 404, such as 402, shows that the stepped reflector may include two stepped reflector portions 846 and 848. The stepped reflector portions 846 and 848 may be formed on the semiconductor substrate 104 / 404 and positioned around the light-emitting region. In some embodiments, the stepped reflector may isolate at least some or substantially all of the light emitted from the light-emitting region. For example, as... Figure 8 As shown, when the height of the stepped reflector cup is higher than the height of the light-emitting area, the stepped reflector cup portions 846 and 848 can isolate at least some or substantially all of the light emitted by the light-emitting area. Therefore, the stepped reflector cup can suppress inter-pixel crosstalk and improve the overall contrast of the LED display.

[0422] In some embodiments, the stepped reflector cup includes one or more stepped structures such as 846-1, 846-2, 846-3, 848-1, 848-2, and 848-3. In some embodiments, the height of each step of the reflector cup may be the same as the height of the LED structure at the same vertical level. For example, stepped structures 846-1 and 848-1 each have the same height as the bottom LED structure. Stepped structures 846-2 and 848-2 each have the same height as the middle LED structure. Stepped structures 846-3 and 848-3 each have the same height as the top LED structure. However, in some embodiments, stepped reflector cup portions 846 and 848 may have the same or different heights. The stepped reflector cup may also reflect light emitted from the light-emitting area upwards. For example, by design, some of the light emitted from the light-emitting area may reach the stepped reflector cup portions 846 and 848 and be reflected upwards through them towards each LED structure within a single pixel multicolor LED device in a different pattern. For example, each step can adjust the focus with a different pattern for the emitted (especially horizontal) light. For instance, the red light from the beam from the LED device can be focused more centrally, while the blue light can be focused more peripherally. Therefore, it can reduce the divergence of light emitted from the light-emitting area and enhance the brightness of a single pixel multicolor LED device.

[0423] In some embodiments, the stepped reflector structure may include or form a cavity surrounding the light-emitting region. The cavity may include a region surrounded by the stepped reflector and located above the semiconductor substrate 404. The cavity may include inner sidewalls, which may include a plurality of inclined surfaces. For example, as... Figure 8 As shown, the stepped reflector cup may include a cavity or surround a cavity, the cavity including the area between the stepped reflector cup portions 846 and 848 and above the semiconductor substrate 404. The light-emitting area may be positioned within the cavity and surrounded by the stepped reflector cup portions 846 and 848.

[0424] In some embodiments, the top of the cavity is higher than the top of the light-emitting area. For example, the top of the cavity included in a stepped reflector cup (e.g., stepped reflector cup portions 846 and 848) is higher than the top of the light-emitting area. In some embodiments, the cavity may include an inner sidewall, and the inner sidewall may include a plurality of inclined surfaces (e.g., inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S, and 848-3S). In some embodiments, the inclination angle (relative to the surface of the substrate 404) of the plurality of inclined surfaces increases from the bottom to the top of the cavity. For example, as Figure 8 As shown, the angles of the tilted surfaces 846-1S, 846-2S, and 846-3S are represented as tilt angles α, β, and γ, respectively. The tilt angles of the tilted surfaces 846-1S, 846-2S, and 846-3S can be the same as those of the tilted surfaces 848-1S, 848-2S, and 848-3S, respectively. In some embodiments, the tilt angles α, β, and γ remain the same or gradually increase from the bottom to the top of the cavity. In some preferred embodiments, the tilt angles α, β, and γ can gradually decrease from the bottom to the top of the cavity, thus allowing the light emitted by the LED device to diverge more towards the upper part of the LED device. However, in some embodiments, the tilt angles α, β, and γ can be any angle according to design. In some embodiments, the cavity can be filled with a silicon-containing material, such as silicon oxide, which can improve optical refraction, increase light transmittance, and / or enhance UV resistance and heat resistance. In some embodiments, the cavity can be empty or a vacuum. In some embodiments, the inclined surfaces (e.g., inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S, and 848-3S) may be straight, curved, wavy, multi-lined, or a combination thereof.

[0425] In some embodiments, the cavity may include multiple sub-cavities. The sub-cavities may be formed or surrounded by various inclined surfaces and may have different dimensions in the horizontal direction. For example, there may be sub-cavities such as... Figure 8The diagram shows three sub-cavities. The bottom sub-cavity may include a region surrounded or defined by the semiconductor substrate 104 / 404, the inclined surfaces 846-1S and 848-1S, and the bottom of the bonding layer 156 / 456. The middle sub-cavity may include a region surrounded or defined by the bottom of the bonding layer 156 / 456, the inclined surfaces 846-2S and 848-2S, and the bottom of the bonding layer 160 / 460. The top sub-cavity may include a region surrounded or defined by the bottom of the bonding layer 160 / 460, the inclined surfaces 846-3S and 848-3S, and the top electrode layer 140 / 440 (or the top opening of the stepped structures 846-3 and 848-3). In some embodiments, the inclined surfaces of the sub-cavities are not arranged in the same plane. For example, as shown... Figure 8 As shown, each sub-cavity can be formed or surrounded by multiple inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S, and 848-3S, and have different dimensions in the horizontal direction. In some embodiments, the inclined surfaces 846-1S, 846-2S, and 846-3S may not be arranged in the same plane, and the inclined surfaces 848-1S, 848-2S, and 848-3S may not be arranged in the same plane. For example, the inclined surfaces 846-1S, 846-2S, and 846-3S are arranged staggered in the vertical direction in different planes.

[0426] In some embodiments, the heights of the sub-cavities can be different. For example, the height of the sub-cavity located in the middle of the cavity can be less than the height of the other sub-cavities. The height of the sub-cavity located at the top of the cavity can be greater than the height of the sub-cavities located at the bottom of the cavity. In other embodiments, each colored LED structure is located in a different sub-cavity within the cavity. For example, the bottom red LED structure is located in the bottom sub-cavity, the top blue LED structure is located in the top sub-cavity, and the middle green LED structure is located in the middle sub-cavity. In some embodiments, the sub-cavities can be filled with a silicon-containing material, such as silicon oxide, which can improve optical refraction, increase light transmittance, and / or enhance UV resistance and heat aging resistance. In some embodiments, the materials of the sub-cavities can be different. For example, the top sub-cavities can be filled with silicon oxide, and the bottom sub-cavities can be filled with epoxy methyl silicone. In some embodiments, the sub-cavities can be empty or vacuum-sealed.

[0427] In some embodiments, the stepped reflector may include a metal. In some embodiments, the stepped reflector may include a dielectric material such as silicon dioxide. In some embodiments, the stepped reflector may include a photosensitive dielectric material. In some embodiments, the photosensitive dielectric material may include SU-8 or photosensitive polyimide (PSPI). In other embodiments, the stepped reflector may include photoresist. In some embodiments, the manufacturing process of the stepped reflector is similar to that described above with reference to the reflector.

[0428] In some embodiments, the single-pixel multicolor LED device 800 further includes one or more reflective coatings. The one or more reflective coatings may be disposed on one or more inclined surfaces of a stepped reflector, for example, on inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S, and 848-3S. The bottom of each layer of the one or more reflective coatings does not contact the individual LED structures, such as the red LED structure, green LED structure, and blue LED structure. The one or more reflective coatings can reflect light emitted from the light-emitting area, thus enhancing the brightness and luminous efficiency of the micro-LED panel or display. For example, light emitted from the light-emitting area can reach the one or more reflective coatings and can be reflected upwards through them.

[0429] The one or more reflective coatings, together with the stepped reflector cup, can utilize the reflection direction and / or intensity of light emitted from the luminous region. For example, the tilt angles α, β, and γ corresponding to the tilted surfaces 846-1S, 846-2S, and 846-3S can decrease from the bottom to the top of the cavity; therefore, the one or more reflective coatings disposed on the tilted surfaces 846-1S, 846-2S, and 846-3S are tilted at the same tilt angle as the tilted surfaces 846-1S, 846-2S, and 846-3S. When light emitted from the luminous region reaches the one or more reflective coatings, the light emitted from the luminous region is reflected by the one or more reflective coatings at tilt angles α, β, and γ. The tilt angles α, β, and γ can be larger, the same, or smaller, or the tilt angles α, β, and γ can be further selected according to a specific design.

[0430] The material of the one or more reflective coatings may be highly reflective, having a reflectivity greater than 60%, 70%, or 80%, capable of reflecting most of the light emitted from the luminous region. In some embodiments, the material of the one or more reflective coatings is similar to that described above with reference to the reflector cup. In some embodiments, the materials of the one or more reflective coatings disposed on each inclined surface may be different. For example, the material of the reflective coating disposed on inclined surface 846-1S may be different from the materials of the reflective coatings disposed on inclined surfaces 846-2S and 846-3S, respectively.

[0431] In some embodiments, one or more of the reflective coatings may be fabricated using one or more electron beam deposition or sputtering processes. In some embodiments, each of the one or more stepped structures, such as 846-1, 846-2, 846-3, 848-1, 848-2, and 848-3, is formed layer-by-layer in a multi-step process. For example, stepped structures such as 846-1 and 848-1 are formed in the same steps before or after the formation of planarized layer 454. Stepped structures such as 846-2 and 848-2 are formed in the same steps before or after the formation of planarized layer 458. Stepped structures such as 846-3 and 848-3 are formed in the same steps before or after the formation of planarized layer 462. In some embodiments, particularly when layer-by-layer planarization is involved in the formation of a single-pixel tri-color LED device, the stepped structure is formed as a result of layer-by-layer processing and layer bonding misalignment of different planarizations including the LED structure. In some embodiments, gaps may exist between different stepped structures such as 846-1, 846-2, and 846-3 due to layer-by-layer processing and layer bonding misalignment resulting from different planarizations of the LED structure. Figure 8 (Not shown in the image).

[0432] In some embodiments, the reflector cup may have a floating structure. Figure 9 It is a single-pixel tri-color LED device 900 with a floating reflector according to some embodiments. Figure 4A A cross-sectional view of the diagonal, such as 402. In some embodiments, although not all Figure 9 As shown, the single-pixel tri-color LED device 900 has a structure similar to any of the single-pixel tri-color LED devices shown in Figures 1-8, and has floating reflector portions such as 946 and 948.

[0433] In some embodiments, the floating reflector cup may surround the light-emitting area, and the bottom of the reflector cup does not directly contact the semiconductor substrate 104 / 404. For example, as Figure 9 As shown, reflector cups 946 and 948 surround the light-emitting area, and the bottoms of reflector cups 946 and 948 do not directly contact the semiconductor substrate 104; for example, a gap exists between the bottom of the reflector cup and the substrate 104 / 404. In some embodiments, this gap is filled by a planarized insulating layer 454. In some embodiments, light emitted from the light-emitting area can reach the reflector cup and be reflected upwards by it. For example, as... Figure 9 As shown, the light emitted from the light-emitting area, including light emitted from the sidewalls and / or top of the LED structure, can reach the reflector cups 946 and 948 and be reflected upwards through them. Therefore, it can reduce the divergence of the light emitted from the light-emitting area and enhance the brightness of a single pixel multicolor LED device.

[0434] In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 104 / 404 can be adjusted according to design requirements. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 104 / 404 can be adjusted during the production of the single-pixel multicolor LED device and the display panel. This distance is fixed and cannot be adjusted when the production of the single-pixel multicolor LED device 900 is completed. In other embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 104 / 404 can be specifically selected during the design process and fixed after the production of the single-pixel multicolor LED device 900 and the display panel. In some embodiments, the distance between the bottom of the reflector cup, such as components 946 and 948, and the top surface of the substrate 404 can be the same as or smaller than the distance between the top surface of the bonding layer 408 at the bottom of the light-emitting layer 412 and the top surface of the substrate 404. In some embodiments, the distance between the bottom of the reflector cup, such as components 946 and 948, and the top surface of the substrate 404 can be greater than the distance between the top surface of the bonding layer 408 at the bottom of the light-emitting layer 412 and the top surface of the substrate 404. By adjusting the gap of the floating reflector cup, specific light from certain parts of the single-pixel multicolor LED device 900 can be prevented from being reflected or blocked, which allows the light to be more focused at selected parts of the device 900.

[0435] In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 0.5 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 1 micrometer. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 140 may be less than 2 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 5 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 10 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 20 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 50 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 75 micrometers. In some embodiments, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 may be less than 100 micrometers. Overall, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 is determined by the bottom height of the light-emitting layer, such as the thickness of the metal bonding layer. In a preferred embodiment, the distance between the bottom of the reflector cup and the top surface of the semiconductor substrate 404 is no more than 20 micrometers.

[0436] In some embodiments, the reflector can isolate at least some of the light emitted by the light-emitting area. For example, such as Figure 9 As shown, when the height of the reflector cup is higher than the height of the light-emitting area, reflector cup portions 946 and 948 can isolate at least some of the light emitted by the light-emitting area. Therefore, the reflector cup can suppress inter-pixel light crosstalk and improve the overall contrast of the LED display. The floating reflector cup has the same or similar composition, shape, and manufacturing process as the reflector cup described above (except for position and orientation).

[0437] Figures 1-9 illustrate only a single-pixel multicolor LED device according to some embodiments. In other embodiments, the reflector cup can have different shapes when viewed from a top or side view. That is, the sidewalls of the reflector cup surrounding the light-emitting area can be circular, triangular, square, rectangular, pentagonal, hexagonal, and octagonal. The sidewalls of the reflector cup can surround a light-emitting area or a single-pixel multicolor LED device, or they can surround a group of light-emitting areas or a group of single-pixel multicolor LED devices. For example, the sidewalls of the reflector cup can surround two or more light-emitting areas or two or more single-pixel multicolor LED devices arranged in the same plane.

[0438] An array of single-pixel multicolor LED devices can be used, each of which may include a reflector cup. Each reflector cup may have a different shape when viewed from a top view or a plan view. For example, the reflector cup of the first single-pixel multicolor LED device may be round, and the reflector cups of adjacent single-pixel multicolor LED devices may be square. Additionally, the reflector cups may be electrically isolated from each other. Reflector cups may also be isolated if a buffer space is provided between adjacent reflector cups, or if the material of the reflector cups may not extend all the way to the boundary with adjacent reflector cups. Alternatively, a reflective coating formed on the sidewalls of the reflector cups may simply extend to cover the gap area between adjacent reflector cups. In another embodiment, the reflector cups may be electrically connected to each other via a common electrode, such as a top electrode.

[0439] Various other modifications, alterations, and variations will be apparent to those skilled in the art regarding the arrangement, operation, and details of the methods and apparatus of the invention disclosed herein, without departing from the spirit and scope of the invention as defined in the appended claims. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents.

[0440] Other embodiments include various subsets that combine or otherwise rearrange the embodiments shown in Figures 1-9 in various other embodiments.

[0441] Various design aspects of a single-pixel multicolor LED device, such as layer dimensions (e.g., width, length, height, and cross-sectional area of ​​each layer), electrode dimensions, the size, shape, spacing, and arrangement of the two or more LED structure layers, bonding layers, reflective layers, and conductive layers, as well as the configuration between the integrated circuit, pixel driver, and electrical connections, are selected (e.g., optimized using cost or performance functions) to obtain the desired LED characteristics. LED characteristics altered based on the aforementioned design aspects include, for example, size, material, cost, manufacturing efficiency, luminous efficacy, power consumption, directivity, luminous intensity, luminous flux, color, spectrum, and spatial radiation pattern.

[0442] Figure 10A This is a circuit diagram of a 1000-matrix matrix of single-pixel tri-color LED devices according to some embodiments. Figure 10A The circuitry includes three pixel drivers 1002, 1004 and 1006 and three tri-color LED devices 1008, 1010 and 1012.

[0443] In some embodiments, the display panel includes multiple pixels, such as millions of pixels, and each pixel includes a tri-color LED device structure. In some embodiments, the LED device structure may be a micro-LED. Micro-LEDs typically have a lateral dimension of 50 micrometers (μm) or less, and may have a lateral dimension of less than 10 μm or even only a few μm.

[0444] In some embodiments, such as 1002, the pixel driver includes multiple transistors and capacitors. Figure 10A (Not shown in the image). The transistor includes a drive transistor connected to a power supply and a control transistor configured with its gate connected to a scan signal bus. The capacitor includes a storage capacitor used to maintain the gate voltage of the drive transistor while the scan signal sets other pixels.

[0445] In this example, each of the three tri-color LED devices, such as 1008, has its own integrated circuit (IC) pixel driver 1002. The tri-color LED device 1008 for a single pixel can be considered as three separate LEDs connected in parallel with different colors. For example, the red LED 1018, green LED 1016, and blue LED 1014 within the same tri-color LED device 1008 are connected to the same IC pixel driver 1002 via a common P-electrode pad or anode.

[0446] In some embodiments, each red LED, green LED, and blue LED within the same tri-color LED device 1008 is connected to a separate N-electrode pad or cathode.

[0447] In some embodiments, all red LEDs from different tri-color LED devices, such as 1018, 1024, and 1030, are connected to the same common N-electrode 1036. All green LEDs from different tri-color LED devices, such as 1016, 1022, and 1028, are connected to the same common N-electrode 1034. All blue LEDs from different tri-color LED devices, such as 1014, 1020, and 1026, are connected to the same common N-electrode 1032. The use of a common electrode simplifies the manufacturing process and reduces the area of ​​the LED device, especially the area occupied by the electrodes.

[0448] In some embodiments, the connections of the P electrode and the N electrode can be switched and interchanged. Figure 10A (Not shown in the image). For example, red LEDs 1018, green LEDs 1016, and blue LEDs 1014 within the same tri-color LED device 1008 are connected to a shared N-electrode pad or cathode. Red LEDs, green LEDs, and blue LEDs within the same tri-color LED device 1008 are connected to separate P-electrode pads or anodes. All red LEDs from different tri-color LED devices, such as 1018, 1024, and 1030, are connected to the same common N-electrode 1036.

[0449] Figure 10B This is a circuit diagram of a 1000-matrix matrix of single-pixel tri-color LED devices according to some embodiments. Figure 10B Similar to Figure 10A The difference lies in that, in this example, each LED structure in each of the three tri-color LED devices, such as 1008, has its own integrated circuit (IC) pixel driver 1002. For example, within the same tri-color LED device 1008, the red LED 1018, green LED 1016, and blue LED 1014 are connected to different IC pixel drivers 1002-1, 1002-2, and 1002-3 respectively via separate P-electrode pads or anodes. This type of P-electrode connection is shown in some embodiments, as can be observed from Figures 1-9.

[0450] In addition, in such Figure 10B In some of the embodiments shown, all LEDs of different colors from different tri-color LED devices are connected to the same common N electrode 1032.

[0451] In some embodiments, the connections of the P electrode and the N electrode can be switched and interchanged. Figure 10B(Not shown in the image). For example, within the same tri-color LED device 1008, the red LED 1018, green LED 1016, and blue LED 1014 are connected to different N-electrode pads or cathodes. All LEDs of different colors in different tri-color LED devices are connected to the same common P-electrode 1032.

[0452] Figure 11 This is a top view of a micro LED display panel 1100 according to some embodiments. The display panel 1100 includes a data interface 1110, a control module 1120, and a pixel area 1150. The data interface 1110 receives data defining the image to be displayed. The source and format of this data will vary depending on the application. The control module 1120 receives input data and converts it into a form suitable for driving the pixels in the display panel. The control module 1120 may include: digital logic and / or a state machine to convert from the received format to a format suitable for the pixel area 1140; shift registers or other types of buffers and memories to store and transfer data; digital-to-analog converters and level converters; and a scan controller including clock circuitry.

[0453] Pixel region 1150 includes a pixel array. Pixels include microLEDs such as multicolor LEDs 1134 integrated with, for example, a pixel driver as described above. In some embodiments, the top of the multicolor LED array is covered by an array of microlenses. Figure 11 (Not shown separately in LED1134). In some embodiments, an array of multicolor LEDs is formed around it with a reflective structure or a reflector cup (not shown separately in LED1134). Figure 11 An array of optically isolated structures (not shown separately in LED1134). In this example, display panel 1100 is a color RGB display panel. It includes red, green, and blue pixels. Within each pixel, the three-color LED 1134 is controlled by a pixel driver. According to the previously shown embodiment, the pixel is in contact with a power supply voltage (not shown), ground via ground pad 1136, and also with a control signal. Although in Figure 11 As not shown, the P electrode of the tri-color LED 1134 and the output of the driving transistor are located within the LED 1134. LED current drive signal connections (between the P electrode of the LED and the output of the pixel driver), ground connections (between the n electrode and system ground), power supply voltage Vdd connections (between the source of the pixel driver and system Vdd), and control signal connections to the pixel driver gate are made according to various embodiments.

[0454] Figure 11 This is just a representative illustration. Other designs will be obvious. For example, the colors don't have to be red, green, and blue. Nor do they have to be arranged in rows or bars. As an example, besides Figure 11In addition to the square matrix arrangement of pixels shown, the hexagonal matrix arrangement of pixels can also be used to form the display panel 1100.

[0455] In some applications, a fully programmable rectangular pixel array is not necessary. Other designs for display panels and displays with various shapes can also be formed using the device structures described herein. One class of examples is specialized applications, including signage and automobiles. For instance, multiple pixels can be arranged in a star or spiral shape to form a display panel, and different patterns on the display panel can be generated by turning the LEDs on and off. Another specialized example is automotive headlights and intelligent lighting, where certain pixels are grouped together to form various lighting shapes, and each group of LED pixels can be turned on or off or otherwise adjusted via individual pixel drivers.

[0456] Even the lateral arrangement of the devices within each pixel can be varied. In Figures 1-9, the LEDs and pixel drivers are arranged vertically, meaning each LED is located on top of its corresponding pixel driver circuit. Other arrangements are also possible. For example, the pixel driver circuit could also be located "behind," "in front of," or "beside" the LEDs.

[0457] Different types of display panels can be manufactured. For example, the resolution of display panels typically ranges from 8×8 to 3840x2160. Common display resolutions include QVGA (320x240 with a 4:3 aspect ratio), XGA (1024x768 with a 4:3 aspect ratio), D (1280x720 with a 16:9 aspect ratio), FHD (1920×1080 with a 16:9 aspect ratio), UHD (3840x2160 with a 16:9 aspect ratio), and 4K (4096×2160). A wide variety of pixel sizes are also available, ranging from submicron and below to 10mm and above. The overall display area size can also vary widely, from diagonally small to tens of micrometers or smaller to hundreds of inches or larger.

[0458] Different applications will also have different requirements for optical brightness and viewing angle. Example applications include direct-view displays for home / office projectors and portable electronics such as light engines for smartphones, laptops, wearable electronics, AR and VR glasses, and retinal projection. Power consumption can vary from as low as a few milliwatts for retinal projectors to up to kilowatts for large-screen outdoor displays, projectors, and smart car headlights. In terms of frame rate, due to the fast response (nanosecond level) of inorganic LEDs, frame rates can reach the kHz level, or even the MHz level for low resolutions.

[0459] Other embodiments include various subsets of the embodiments shown in Figures 1-11 that are combined and rearranged in various other embodiments, such as having and not having a reflective layer, having and not having a planarized layer, having and not having a reflector cup structure including various shapes and positioning types, having and not having a refractive layer, having and not having a microlens, having and not having spacers, and having and not having multicolor LED pixel devices / units with different electrode connection structures.

[0460] While the detailed description contains many details, these should not be construed as limiting the scope of the invention, but merely as illustrating different examples and aspects of the invention. It should be understood that the scope of the invention includes other embodiments not discussed in detail above. For example, the methods described above can be applied to the integration of non-LED and OLED functional devices with control circuitry that is not pixel-driven. Examples of non-LED devices include vertical-cavity surface-emitting lasers (VCSELs), photodetectors, microelectromechanical systems (MEMS), silicon photonic devices, power electronic devices, and distributed feedback lasers (DFBs). Examples of other control circuitry include current drivers, voltage drivers, transimpedance amplifiers, and logic circuits.

[0461] The foregoing description of the disclosed embodiments is provided to enable making or using the embodiments and variations thereof described herein. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

[0462] The features of this invention can be implemented using a computer program product or with the aid of a computer program product, such as a storage medium (of various media) or a computer-readable storage medium (of various media), wherein instructions are stored thereon or thereon, which can be used to program a processing system to perform any of the features presented herein. The storage medium may include, but is not limited to, high-speed random access memory, such as DRAM, SRAM, DDRRAM, or other random access solid-state memory devices, and may include non-volatile memory, such as one or more disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state memory devices. The memory may optionally include one or more storage devices located remotely from the CPU. The non-volatile memory devices within the memory, or optionally within the memory, include non-transitory computer-readable storage media.

[0463] Features of the invention, stored on any machine-readable medium (of various kinds), can be contained in software and / or firmware for controlling the hardware of a processing system and enabling the processing system to interact with other entities using the results of the invention. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0464] It should be understood that although this document may use terms such as “firstly” and “secondly” to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0465] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the claims. As used in the description of the embodiments and the appended claims, the singular forms “a,” “an,” and “this” are intended to include multiple forms as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items. It should also be understood that the terms “comprising” and / or “including”, when used in this specification, specify the presence of said features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups.

[0466] As used herein, the term "if" can be interpreted as meaning, depending on the context, that the prerequisite of a statement is true "in the case of," "when," or "in response to detection." Similarly, the phrases "if it is determined that [the prerequisite of that statement is true]," "if [the prerequisite of the statement is true]," or "when [the prerequisite of the statement is true]" can be interpreted as meaning, depending on the context, that the stated prerequisite is true "when determined," "in response to determined," "according to determined," "when detected," or "in response to detection."

[0467] The foregoing description, used for illustration, has been described with reference to specific embodiments. However, the illustrative discussion above is not intended to be exhaustive or to limit the claims to the precise forms disclosed. Many modifications and variations can be made in light of the foregoing teachings. The embodiments were chosen and described in order to best explain the principles of practical application and operation, thereby enabling others skilled in the art to implement them.

Claims

1. A miniature LED pixel unit, comprising, Semiconductor substrate; A light-emitting region formed on the semiconductor substrate includes a plurality of colored LED structures. The bottom of each of the plurality of colored LED structures is connected to a corresponding bonding metal layer in the light-emitting region. Each of the plurality of colored LED structures includes a light-emitting layer and a reflective structure located at the bottom of the light-emitting layer. The plurality of colored LEDs includes a first colored LED structure and a second colored LED structure. The first colored LED structure includes a first light-emitting layer, a first bottom reflective layer formed at the bottom of the first light-emitting layer, and a first top reflective layer formed at the top of the first light-emitting layer. The second colored LED structure includes a second light-emitting layer, a second bottom reflective layer formed at the bottom of the second light-emitting layer, and a second top reflective layer formed at the top of the second light-emitting layer. A top electrode layer covers each of the plurality of color LED structures and is electrically contacted with each of the plurality of color LED structures, wherein the semiconductor substrate is electrically connected to each of the plurality of color LED structures; The reflector cup surrounding the light-emitting area; and A refractive structure is formed between the reflector and the light-emitting area; in: Before the light emitted by the first light-emitting layer reaches the reflector and is reflected upwards, it is reflected between the first bottom reflective layer and the first top reflective layer and then propagates in a roughly horizontal direction. Before the light emitted by the second light-emitting layer reaches the reflector and is reflected upward, it propagates approximately horizontally between the second bottom reflective layer and the second top reflective layer.

2. The microLED pixel unit according to claim 1 further includes a microlens formed on the top surface of the refractive structure.

3. The micro LED pixel unit according to claim 2, wherein, The lateral dimension of the microlens is not less than the lateral dimension of the light-emitting area.

4. The micro LED pixel unit according to claim 2, wherein, The reflector cup has a top opening area, and the lateral dimension of the microlens is smaller than the lateral dimension of the top opening area.

5. The micro LED pixel unit according to claim 1 further includes a bottom dielectric layer formed between the bottom of the reflector and the semiconductor substrate.

6. The micro LED pixel unit according to claim 1 further includes a top conductive layer formed on top of the light-emitting area, the top conductive layer being electrically connected to the reflector.

7. The micro LED pixel unit according to claim 6, wherein, The top conductive layer is in direct contact with the top or bottom of the reflector.

8. The micro LED pixel unit according to claim 1, wherein, The top of the refractive structure is higher than the top of the reflector.

9. The micro LED pixel unit according to claim 1, wherein, Each of the plurality of colored LED structures includes a bottom conductive contact layer and a top conductive contact layer, and the light-emitting layer is formed between the bottom conductive contact layer and the top conductive contact layer; wherein, The bottom conductive contact layer is electrically connected to the semiconductor substrate via contact vias through the reflective structure and the corresponding bonding metal layer, and The top surface of the top conductive contact layer of the top colored LED structure contacts the top electrode layer, and the edge of the top conductive contact layer of the colored LED structure below the top colored LED structure contacts the top electrode layer.

10. The micro LED pixel unit according to claim 1, wherein, The semiconductor substrate is an IC substrate.

11. The micro LED pixel unit according to claim 1, wherein, The reflector is a stepped reflector that forms a cavity surrounding the light-emitting area.

12. The micro LED pixel unit according to claim 11, wherein, The inner wall of the cavity includes multiple inclined surfaces.

13. The micro LED pixel unit according to claim 12, wherein, The angles of the plurality of tilted surfaces relative to the surface of the semiconductor substrate decrease from the bottom of the cavity to the top of the cavity.

14. The micro LED pixel unit according to claim 12, wherein, The sub-cavities formed by the plurality of inclined surfaces have different dimensions in the horizontal direction.

15. The micro LED pixel unit according to claim 14, wherein, The inner walls of the sub-cavities are not arranged in the same plane.

16. The micro LED pixel unit according to claim 14, wherein, The heights of the sub-cavities are different.

17. The micro LED pixel unit according to claim 14, wherein, The height of the sub-cavity located in the middle of the cavity is less than the height of the other sub-cavities.

18. The micro LED pixel unit according to claim 14, wherein, The height of the sub-cavity located at the top of the cavity is greater than the height of the sub-cavity located at the bottom of the cavity.

19. The micro LED pixel unit according to claim 11, wherein, The plurality of colored LED structures also includes a top colored LED structure.

20. The micro LED pixel unit according to claim 19, wherein, The top of the cavity is higher than the top of the top colored LED structure.

21. The micro LED pixel unit according to claim 11, wherein, The cavity includes multiple sub-cavities, and each of the multiple colored LED structures is located in a different sub-cavity within the multiple sub-cavities.

22. The micro LED pixel unit according to claim 1, wherein, The reflector cup is made of metal.

23. The micro LED pixel unit according to claim 19, wherein, An extension portion extends from one side of the light-emitting layer of the color LED structure below the top color LED structure, and a contact via connects the extension portion to the top electrode layer.

24. The micro LED pixel unit according to claim 1, wherein, The multiple colored LED structures have the same central axis.

25. The micro LED pixel unit according to claim 1, wherein, The reflective structure includes a reflective layer with a thickness ranging from 5 nm to 10 nm, and the thickness of each of the plurality of color LED structures does not exceed 300 nm.

26. The micro LED pixel unit according to claim 1, wherein, The material of the top electrode layer includes one or more of graphene, indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), or fluorine-doped tin oxide (FTO).

27. The micro LED pixel unit according to claim 1, wherein, Each of the plurality of color LED structures includes a corresponding extension portion extending from one side of the respective color LED structure, the corresponding extension portion being electrically connected to the top electrode layer via a corresponding first contact via, and the bottom of each of the plurality of color LED structures being electrically connected to the semiconductor substrate via a corresponding second contact via.

Images