Systems and methods for multi-color LED pixel cells

Abstract

A micro multi-color LED device includes two or more LED structures for emitting a series of color light. The two or more LED structures are vertically stacked to vertically and / or horizontally mix light emitted by the two or more LED structures and reflect upward via some of the reflective structures. In some embodiments, each LED structure is connected with a pixel driver and / or a common electrode. The LED structures are bonded together through the bonding layer. In some embodiments, a planarization layer encloses each LED structure or micro multi-color LED device. In some embodiments, one or more of a reflective layer, a refractive layer, a microlens, a spacer, and a reflective cup structure are implemented in the device to improve LED luminous efficiency. The display panel including the micro three-color LED device array has high resolution and high illumination brightness.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims U.S. Provisional Patent Application No. 62 / 863,559, filed on June 19, 2019, entitled “Systems and Methods for Coaxial Multi-Color LEDs”; U.S. Provisional Patent Application No. 63 / 013,358, filed on April 21, 2020, entitled “Light-Emitting Diode Chip Structures with Reflective Elements”; U.S. Provisional Patent Application No. 63 / 013,370, filed on April 21, 2020, entitled “Light-Emitting Diode Chip Structures with Reflective Elements”; U.S. Provisional Patent Application No. 63 / 034,391, filed on June 3, 2020, entitled “Systems and Methods for Multi-Color LED Pixel Unit with Vertical and priority to U.S. Provisional Patent Application No. 63 / 034,394, filed on June 3, 2020, and entitled “Systems and Methods for Multi-Color LED Pixel Unit with Horizontal Light Emission,” each of which is incorporated herein by reference. Technical Field

[0002] The present disclosure relates generally to light emitting diode (LED) display devices, and more particularly, to systems and manufacturing methods for LED semiconductor devices for emitting different color lights with high brightness and micrometer-scale pixel size. Background Art

[0003] With the development of mini LED and micro LED technology in recent years, consumer devices and applications such as augmented reality (AR), virtual reality (VR), projection, head-up display (HUD), mobile device display, wearable device display and vehicle display require LED panels with improved resolution and brightness. For example, an AR display integrated in goggles and positioned close to the wearer's eyes can have a size such as the size of a fingernail, while still requiring HD (1280x720 pixels) or higher clarity. Many electronic devices require a certain pixel size, a certain distance between adjacent pixels, a certain brightness and a certain viewing angle of the LED panel. Generally, when trying to achieve maximum resolution and brightness on a small display, it is challenging to maintain resolution and brightness requirements at the same time. On the contrary, in some cases, pixel size and brightness are difficult to balance at the same time because they have a roughly opposite relationship. For example, each pixel obtains high brightness, which results in its low resolution. Or, obtaining high resolution will reduce brightness.

[0004] Typically, at least red, green and blue are superimposed to reproduce a wide range of colors. In some cases, in order to include at least red, green and blue within a pixel area, independent monochromatic LEDs are prepared on different non-overlapping areas within the pixel area. The prior art faces the challenge of increasing the effective illumination area within each pixel when the distance between adjacent LEDs is determined. On the other hand, when the illumination area of ​​a single LED is determined, further improving the overall resolution of the LED panel will be a difficult task because LEDs of different colors must occupy their designated areas within a single pixel.

[0005] Active matrix liquid crystal display (LCD) and organic light emitting diode (OLED) displays combined with thin film transistor (TFT) technology are becoming increasingly popular in today's commercial electronic devices. These displays are widely used in personal laptops, smart phones and personal digital assistants. Millions of pixels work together to create the image on the display. The TFT acts as a switch to turn each pixel on and off individually, making the pixel bright or dark, allowing for convenient and efficient control of each pixel and the entire display.

[0006] However, conventional LCD displays have the disadvantage of low light efficiency, resulting in high power consumption and limited battery operating time. Although active matrix organic light emitting diode (AMOLED) display panels generally consume less power than LCD panels, AMOLED display panels are still the main power consumption device in battery-powered devices. In order to extend battery life, it is necessary to reduce the power consumption of display panels.

[0007] Conventional inorganic semiconductor light emitting diodes (LEDs) have demonstrated excellent light 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 present images on a display. Both monochrome and full-color display panels can be produced using a variety of manufacturing methods.

[0008] However, the integration of thousands or even millions of micro-LEDs with an array of pixel drive circuits is challenging. Various manufacturing methods have been proposed. In one method, the control circuit is prepared on a substrate and the LEDs are prepared on a separate substrate. The LEDs are transferred to an intermediate substrate and the original substrate is removed. Then, the LEDs on the intermediate substrate are picked up and one or several are placed on the substrate with the control circuit in turn. However, this manufacturing process is inefficient, expensive and unreliable. In addition, there are no ready-made production tools for large-scale transfer of micro-LEDs. Therefore, new tools must be developed.

[0009] In another method, the entire LED array with the original substrate is aligned with the control circuit and bonded to the control circuit using metal bonding. The substrate with the LEDs is retained in the final product, which may cause optical crosstalk. In addition, the thermal mismatch between the two different substrates generates stress at the bonding interface, which may cause reliability issues. In addition, compared with monochrome display panels, multi-color display panels generally require more LEDs and LEDs of different colors grown on different substrate materials, making the traditional production process more complicated and inefficient.

[0010] Display technology is becoming more and more popular in today's commercial electronic devices. These display panels are widely used in fixed large screens such as liquid crystal display televisions (LCD TVs) and organic light emitting diode televisions (OLED TVs) and portable electronic devices such as personal notebook computers, smart phones, tablet computers and wearable electronic devices. The development direction of fixed large screen technology is to achieve a large viewing angle 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 film compensated super twisted nematic (FSTN) have been developed to achieve a large viewing angle for all pixel light sources in the display panel.

[0011] However, most portable electronic devices are designed primarily for a single user, and the screen orientation of these portable devices should be adjusted to the best viewing angle for the corresponding user rather than a wide viewing angle that accommodates multiple viewers. For example, a suitable viewing angle for a user may be perpendicular to the screen surface. In this case, the light emitted at a wide viewing angle is mostly wasted compared to a fixed large screen. In addition, a wide viewing angle may cause privacy issues when using portable electronic devices in public areas.

[0012] In addition, 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 are able to project images by optically modulating parallel light emitted from a light source, for example, a portion of the light 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, which reduces the efficiency of the projection system. In addition, in order to provide parallel light, complex illumination optical components are required to collect the divergent light emitted by the light source. The illumination optical components not only make the system bulky, but also introduce additional light losses into the system, which further affects the performance of the system. In conventional projection systems, typically less than 10% of the illumination light generated by the light source is used to form a projected image.

[0013] Light emitting diodes (LEDs) made of semiconductor materials can be used in monochrome or full-color displays. In current displays using LEDs, LEDs are usually used as light sources to provide light that is optically modulated by, for example, an LCD or DMD panel. That is, the light emitted by the LED does not form an image itself. LED displays that include an LED panel with multiple LED dies as imaging devices have also been studied. In such LED displays, the LED panel is a self-emitting imaging device, in which each pixel can include one LED die (monochrome display) or multiple LED dies, each die representing a primary color (full-color display).

[0014] However, the light emitted by the LED die arises from spontaneous emission and is therefore non-directional, resulting in a large divergence angle. The 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 the micro-LED can be utilized. This can significantly reduce 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 optical crosstalk between pixels, loss of clarity, and loss of contrast. Traditional solutions to reduce large divergence angles may not be able to effectively process the overall light emitted by the micro-LED, and may only utilize the central portion of the light emitted by the micro-LED, leaving the rest of the light emitted at a more oblique angle unutilized.

[0015] In summary, there is a need to provide an LED structure for a display panel to address the above-mentioned shortcomings and other defects. Summary of the invention

[0016] There is a need for improved multicolor LED designs that improve and help address the shortcomings of conventional display systems such as those described above. In particular, there is a need for LED device structures that can simultaneously improve brightness and resolution while effectively maintaining low power consumption. There is also a need for a display panel that reduces viewing angles to better protect user privacy, and / or reduces light waste to reduce power consumption, and reduces light interference between pixels to provide a better image.

[0017] The multicolor LED device described herein integrates at least three micro-LED structures, which are arranged at different layers to form a vertically stacked device structure and receive control current using separate electrodes. By arranging at least three LED structures to be aligned along the same axis as disclosed herein, the system effectively improves the light illumination efficiency within a single pixel area and simultaneously improves the resolution of the LED panel.

[0018] 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 microns to about 20 microns, to about 10 microns, and / or preferably to about 5 microns or less. Many efforts have been made to reduce the pitch. When the pitch size is determined, the area of ​​a single pixel is fixed.

[0019] The multicolor coaxial LED system described in this article makes it possible to emit light mixed with different colors from a single pixel area without using additional areas to accommodate LED structures with different colors. Therefore, the occupied area of ​​a single pixel is significantly reduced and the resolution of the micro LED panel can be improved. At the same time, the concentration of different colors of light at the boundary of a micro LED device greatly improves the brightness within a single pixel area.

[0020] 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 manufacturing. For example, the LED structure can be directly bonded to a substrate with a pixel driver without introducing an intermediate substrate, which simplifies the manufacturing steps and thus improves the reliability and performance of the LED chip. In addition, no substrate for the micro-LED structure is retained in the final multi-color device, so crosstalk and mismatch can be reduced. In addition, planarization is applied to each LED structure within a 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 a planarization layer with less damage to the existing structure.

[0021] The multicolor micro-LED devices described herein may include vertical light emission and horizontal light emission, or any combination thereof, where vertical light emission is, for example, light from the stacked individual LED structures being emitted approximately vertically relative to the surface of the substrate, and horizontal light emission is, for example, light from the stacked individual LED structures being emitted horizontally relative to the surface of the substrate and then being reflected approximately vertically by some reflective structures. Since the vertically emitted light needs to pass through all the different layers within the multicolor micro-LED device, improved light propagation and light reflection of each layer is achieved. Compared to vertical light emission, the light emitted horizontally from the stacked individual LED structures does not need to pass through all the layers above a particular structure. Therefore, horizontal light emission can have better light propagation efficiency and produce better light conspicuity.

[0022] Various embodiments include a display panel with an integrated microlens array. The display panel typically includes an array of pixel light sources (e.g., LEDs, OLEDs) electrically coupled to corresponding pixel drive circuits (e.g., FETs). 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 an integrated optical spacer to maintain a gap between the microlenses and the pixel drive circuit.

[0023] The microlens array reduces the divergence angle of the light generated by the pixel light source and the available viewing angle of the display panel. This in turn reduces power waste, increases brightness and / or better protects user privacy in public areas.

[0024] Display panels incorporating microlens arrays can be manufactured using a variety of production methods, resulting in a wide variety of device designs. In one aspect, the microlens array is manufactured directly as a protrusion or mesa of a substrate with pixel light sources. In some aspects, techniques such as self-assembly, high temperature reflow, grayscale mask lithography, molding / imprinting / stamping, and dry etching pattern transfer can be used to manufacture the microlens array.

[0025] Other aspects include components, devices, systems, improvements, methods and processes including methods of production, applications, and other technologies related to any of the above.

[0026] Some exemplary embodiments include a reflective cup disposed on a semiconductor substrate and surrounding a light emitting area, such as an area where light is emitted from a multicolor micro-LED device. The reflective cup can reduce the divergence of light emitted from the light emitting area and suppress light crosstalk between adjacent pixel units. For example, the reflective cup can utilize light at an oblique 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. In addition, the reflective cup can block light emitted by micro-LEDs in adjacent pixel units, which can effectively suppress light crosstalk between pixels and improve color contrast and clarity. Exemplary embodiments of the present disclosure can improve projection brightness and contrast, thereby reducing power consumption in projection applications. Exemplary embodiments of the present disclosure also improve the directionality of light emission from the display, thereby providing users with better image quality and protecting user privacy in direct-view applications. Exemplary embodiments of the present disclosure can provide multiple advantages. One advantage is that exemplary embodiments of the present disclosure can suppress light crosstalk between pixels and improve brightness. Exemplary embodiments of the present disclosure can suppress light crosstalk between pixels at a smaller pitch while increasing brightness within a single pixel in a power-efficient manner.

[0027] In some exemplary embodiments, a single pixel multicolor LED device may include one or more top electrodes integrated with a reflective cup. The top electrode may be electrically connected to the top electrode layer. The top electrode integrated with the reflective cup may make the single pixel multicolor LED device structure more compact and simplify the manufacturing process. By using the top electrode, the reflective cup may be used as a common P electrode or N electrode of the single pixel multicolor LED device, and thus a compact structure of the single pixel multicolor LED device may be provided.

[0028] In some exemplary embodiments, in addition to the reflective cup, the micro LED pixel unit may further include a micro lens. The micro lens may be aligned with the light emitting area and reduce the divergence of the light emitted by the light source, reducing the available viewing angle of the single pixel multi-color LED device. For example, the micro lens may be coaxially aligned with the light emitting area and positioned on the light emitting area and on the top of the reflective cup. A portion of the light emitted by the light emitting area may directly reach the micro lens and pass through the micro lens; another portion may reach the reflective cup and be reflected by the reflective cup, and then reach the micro lens and pass through the micro lens. Therefore, the divergence of light can be reduced, and the available viewing angle can be reduced to such an extent that the display and panel using the single pixel multi-color LED device can be seen by a user perpendicular to the surface of the display and panel. In turn, power waste can be reduced and brightness can be increased and / or user privacy can be better protected in public areas. In another example, the micro lens may be coaxially aligned with the light emitting area, located on the light emitting area and surrounded by the reflective cup. A portion of the light emitted by the light-emitting area can directly reach the microlens and pass through the microlens; another portion of the light can reach the reflector cup and be reflected by the reflector cup, then reach the microlens and pass through the microlens; the remaining light can reach the reflector cup without passing through the microlens and be reflected by the reflector cup. Therefore, divergence can be reduced, and the available viewing angle can be reduced to the extent that the display and panel using the single pixel multi-color LED device can be seen by several users. This can also reduce power waste, increase brightness and / or properly protect user privacy in public areas.

[0029] In some exemplary embodiments, a single pixel multicolor LED device may further include a spacer. The spacer may be an optically transparent layer formed to provide an appropriate spacing between the microlens and the light emitting area. For example, in a case where the microlens is disposed above a reflective cup, the spacer may be disposed between the microlens and the top of the reflective cup. Thus, light emitted from the light emitting area may pass through the spacer and then through the microlens. The spacer may also fill the area surrounded by the reflective cup to increase the refractive index of the medium surrounding the light emitting area. Thus, the spacer may change the optical path of the light emitted by the light emitting area. By employing a microlens, the light extraction efficiency of the single pixel multicolor LED device may be improved to further improve the brightness of, for example, a micro LED display panel.

[0030] 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 area. The cavity may be formed by a plurality of inclined surfaces surrounding the light emitting area. The subcavity may be formed by a plurality of inclined surfaces and may have different sizes in the horizontal direction. The stepped reflector may be arranged on a semiconductor substrate. The stepped reflector may reduce the divergence of light emitted by the light emitting area and suppress light crosstalk between adjacent pixel units. For example, the stepped reflector may utilize light at an inclined angle by reflecting light in different reflection directions. In addition, the stepped reflector may block light emitted from micro-LEDs in adjacent pixel units, which may effectively suppress light crosstalk between pixels and improve color contrast and clarity. Exemplary embodiments of the present disclosure may improve projection brightness and contrast, and thus reduce power consumption in projection applications. Exemplary embodiments of the present disclosure may also improve the directionality of light emission from a display, and thus provide users with better image quality and protect user privacy in direct-view applications.

[0031] The multicolor micro-LED devices described in this article can improve both brightness and resolution and are suitable for current display panels, especially for high-definition AR devices and virtual reality (VR) glasses.

[0032] Some exemplary embodiments provide a multi-color 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 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 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.

[0033] 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.

[0034] 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.

[0035] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing 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 higher than 60%.

[0036] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing 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.

[0037] 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.

[0038] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the first reflective structure also includes a first transparent layer on the first high reflectivity layer; the second reflective structure also includes a second transparent layer on the second high reflectivity layer; and the third reflective structure also includes a second transparent layer on the third high reflectivity layer.

[0039] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing 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.

[0040] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure also includes a first bottom electrode conductive contact layer, the second color LED structure also includes a second bottom electrode conductive contact layer, and the third color LED structure also 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.

[0041] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing 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.

[0042] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, a first extension portion extends from one side of a first light-emitting layer; a second extension portion extends from one side of a 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 a second dielectric bonding layer and a third dielectric bonding layer to connect the first extension portion, the second extension portion, and the third extension portion to a top electrode layer.

[0043] Some exemplary embodiments provide a micro LED pixel unit, comprising 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 a top of the reflective optical isolation structure is higher than a top of the light emitting region.

[0044] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, a micro lens is located on top of the light emitting area.

[0045] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a top of the reflective optical isolation structure is higher than a top of the micro lens.

[0046] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective optical isolation structure has a top opening, and a lateral area of ​​the micro lens is smaller than a lateral area of ​​the top opening.

[0047] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the lateral size of the microlens is larger than the effective light-emitting area of ​​the first color LED structure; the lateral size of the microlens is larger than the effective light-emitting area of ​​the second color LED structure; and the lateral size of the microlens is larger than the effective light-emitting area of ​​the third color LED structure.

[0048] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a lateral dimension of the first color LED structure, a lateral dimension of the second color LED structure, and a lateral dimension of the third color LED structure are the same.

[0049] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure have a same central axis.

[0050] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first dielectric bonding layer is transparent, the second dielectric bonding layer is transparent, and the third dielectric bonding layer is transparent.

[0051] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the thickness of the first reflective structure is 5nm to 10nm; the thickness of the second reflective structure is 5nm to 10nm; the thickness of the third reflective structure is 5nm to 10nm; the thickness of the first LED structure does not exceed 300nm; the thickness of the second LED structure does not exceed 300nm; and the thickness of the third LED structure does not exceed 300nm.

[0052] Some exemplary embodiments provide a multi-color micro-LED pixel unit for a display panel, comprising: a first LED structure formed on an IC substrate that emits a first color of 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 of 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 multi-color 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.

[0053] Some exemplary embodiments provide a micro-LED pixel unit, comprising: 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.

[0054] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, a first reflective structure is formed at the bottom of a first color LED structure; a second reflective structure is formed at the bottom of a second color LED structure; and a third reflective structure is formed at the bottom of a third color LED structure.

[0055] Some exemplary embodiments provide a micro LED pixel unit, comprising: an IC substrate; a light emitting area formed on the IC substrate and comprising at least one LED structure and at least one dielectric bonding layer, wherein each dielectric bonding layer has a planar top surface covering a 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 reflective cup structure having a cavity and surrounding the light emitting area.

[0056] 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.

[0057] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light emitting area formed on the semiconductor substrate, the light emitting area comprising 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 a 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 reflective cup structure formed around the light emitting area; and a refractive structure formed between the stepped reflective cup structure and the light emitting area.

[0058] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective cup structure has a top opening, and a lateral area of ​​the micro lens is smaller than a lateral area of ​​the top opening.

[0059] 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.

[0060] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting area formed on the semiconductor substrate; a reflective optical isolation structure surrounding the light-emitting area; and a top electrode layer covering the light-emitting area and electrically connected to the reflective optical isolation structure, wherein the top electrode layer electrically contacts the reflective optical isolation structure.

[0061] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, an edge of the top electrode layer touches the reflective optical isolation structure.

[0062] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the light-emitting area includes: at least one LED structure and at least one dielectric bonding 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.

[0063] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective optical isolation structure is a floating reflective 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 stepped reflective cup structure.

[0065] Some exemplary embodiments provide a micro LED pixel unit, comprising at least: a semiconductor substrate; a light-emitting area formed on the semiconductor substrate; a floating reflective optical isolation structure surrounding the light-emitting area, 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 area, wherein the top electrode layer is in contact with the floating reflective optical isolation structure.

[0066] In some exemplary embodiments of a 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.

[0067] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure also includes a first bottom electrode conductive contact layer, and the second color LED structure also 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.

[0068] Some exemplary embodiments provide a micro LED pixel unit, including: a semiconductor substrate; a light-emitting area formed on the semiconductor substrate; a top electrode layer covering the light-emitting area and electrically contacting the light-emitting area; a reflective cup structure formed around the light-emitting area, wherein the top electrode layer is electrically connected to the reflective cup structure, and the semiconductor substrate is electrically connected to the reflective cup structure; and a refractive structure formed between the reflective cup structure and the light-emitting area.

[0069] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light emitting area formed on the semiconductor substrate, the light emitting area comprising at least one LED structure and a bonding layer located at the bottom of each LED structure, wherein each LED structure comprises 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 reflective cup structure formed around the light emitting area; and a refractive structure formed between the reflective cup structure and the light emitting area.

[0070] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light-emitting area formed on the semiconductor substrate, the light-emitting area comprising at least one LED structure and a bonding layer located at the bottom of each LED structure, wherein the LED structure comprises 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 reflective cup structure surrounding the light-emitting area, light emitted from the side walls of the first light-emitting layer and the second light-emitting layer along a horizontal plane reaches the stepped reflective cup structure and is reflected upward by the stepped reflective cup structure, wherein the top of the stepped reflective cup structure is higher than the top of the light-emitting area.

[0071] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light emitting area formed on the semiconductor substrate, the light emitting area comprising at least one LED structure and a metal bonding layer located at the bottom of each LED structure, wherein the LED structure comprises 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 reflective cup structure surrounding the light emitting area, wherein the floating reflective cup structure is positioned at a certain distance from the semiconductor substrate, and light emitted from the side walls of the first light emitting layer and the second light emitting layer along the horizontal plane reaches the floating reflective cup structure and is reflected upward by the floating reflective cup structure.

[0072] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bottom of the floating reflective cup structure is higher than a top surface of the semiconductor substrate.

[0073] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the floating reflector structure is a stepped reflector structure.

[0074] In some exemplary embodiments of a 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.

[0075] 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 comprised of a solid inorganic material or a plastic material.

[0076] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the second LED structure is embedded within the second planarized transparent dielectric layer.

[0077] 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 comprised of a solid inorganic material or a plastic material.

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

[0079] In some exemplary embodiments of a 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 the first transparent dielectric bonding layer.

[0080] 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.

[0081] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, a first LED structure includes a first light-emitting layer; a first side portion extends from one side of the first light-emitting layer; a second LED structure includes a second light-emitting layer; a second side portion extends from one side of the second light-emitting layer; and a third contact in a third via hole passing through a second transparent dielectric bonding layer connects the first side portion and the second side portion to a top electrode layer.

[0082] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, an optical isolation structure is formed around the micro LED pixel unit.

[0083] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the optical isolation structure is a reflective cup.

[0084] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a lateral dimension of the first LED structure is the same as a lateral dimension of the second LED structure.

[0085] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first LED structure and the second LED structure have a same central axis.

[0086] 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.

[0087] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing 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.

[0088] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bonding metal layer is formed at the bottom of the first LED structure.

[0089] Some exemplary embodiments provide a micro-light 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 bonding metal layer is formed at the bottom of the first color LED structure, and is configured to bond the IC substrate and the first color LED structure; a second bonding metal layer is formed on the 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 is 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 electrically contacting 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 reflective cup, surrounding the first color LED structure and the second color LED structure, and light emitted from the first light-emitting layer and the second light-emitting layer in a horizontal direction reaches the reflective cup and is reflected upward by the reflective cup.

[0090] 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 higher than 60%.

[0091] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a material of the first reflective layer or the second reflective layer includes one or more of Rh, Al, Ag, or Au.

[0092] 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, the two first reflective layers have different refractive indices, and wherein the second reflective structure includes two second reflective layers, the two second reflective layers have different refractive indices.

[0093] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the two first reflective layers include SiO 2 and Ti 3 O 5 , respectively, and the two second reflective layers include SiO 2 and Ti 3 O 5 , respectively.

[0094] 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.

[0095] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first transparent layer includes one or more of indium tin oxide (ITO) or SiO2, and the second transparent layer includes one or more of ITO or SiO2.

[0096] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure also includes a first bottom conductive contact layer and a first top conductive contact layer, and the second color LED structure also includes a second bottom conductive contact layer and a second top conductive contact layer; the first light-emitting layer is located between the first bottom conductive contact layer and the first top conductive contact layer, and the 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 the first contact via 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 the second contact via; and the edge of the first top conductive contact layer is in contact with the top electrode layer, and the top surface of the second top conductive contact layer is in contact with the top electrode layer.

[0097] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the material of the reflective cup includes metal.

[0098] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, a micro lens is formed over the top electrode layer.

[0099] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a spacer is formed between the micro lens and the top electrode layer.

[0100] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the material of the spacer includes silicon oxide.

[0101] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing exemplary embodiments, the lateral size of the microlens is larger than the lateral size of the effective light-emitting area of ​​the first LED structure; the lateral size of the microlens is larger than the lateral size of the effective light-emitting area of ​​the second LED structure.

[0102] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure and the second color LED structure have the same lateral dimension.

[0103] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the first color LED structure and the second color LED structure have a same central axis.

[0104] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, a thickness of at least one first reflective layer is in the range of 5nm to 10nm, and a thickness of at least one second reflective layer is in the range of 5nm to 10nm, and wherein a thickness of the first color LED structure is not greater than 300nm, and a thickness of the second color LED structure is not greater than 300nm.

[0105] Some exemplary embodiments provide a micro-LED pixel unit, comprising: an IC substrate; a light-emitting area, formed on the IC substrate, comprising 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 area, wherein each of the plurality of color LED structures comprises 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 reflective cup forming a cavity, surrounding the light-emitting area, wherein light emitted in a horizontal direction from a side wall of the light-emitting layer of each of the plurality of color LED structures reaches the reflective cup and is reflected upward by the reflective cup.

[0106] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, an inner sidewall of the cavity includes a plurality of inclined surfaces.

[0107] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the angles of the plurality of inclined surfaces relative to the IC substrate surface decrease from the bottom of the cavity to the top of the cavity.

[0108] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the subcavities formed by the plurality of inclined surfaces have different sizes in a horizontal direction.

[0109] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, inner sidewalls of the subcavities are not arranged in the same plane.

[0110] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, heights of the subcavities are different.

[0111] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a height of a sub-cavity located in the middle of the cavity is smaller than heights of other sub-cavities.

[0112] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, a height of a sub-cavity located at a top of the cavity is greater than a height of a sub-cavity located at a bottom of the cavity.

[0113] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the plurality of color LED structures further includes a top color LED structure.

[0114] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a top of the cavity is higher than a top of the top color LED structure.

[0115] 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 of the plurality of sub-cavities.

[0116] In some exemplary embodiments of a 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.

[0117] 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 materials of SiO2, Al2O3, Si3N4, phospho-silicate glass (PSG) and boro-phospho-silicate glass (BPSG).

[0118] 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-on glass (SOG).

[0119] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, each of a 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; and wherein the bottom conductive contact layer is electrically connected to the IC substrate through a contact via through the reflective structure and the corresponding bonding metal layer, and wherein the top surface of the top conductive contact layer of the top color LED structure is in contact with the top electrode layer, and an edge of the top conductive contact layer of the color LED structure below the top color LED structure is in contact with the top electrode layer.

[0120] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, an extension extends from a side of the light emitting layer of the color LED structure below the top color LED structure, and a contact via connects the extension to the top electrode layer.

[0121] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a lateral dimension of the micro lens is larger than a light emitting dimension of each of the plurality of color LED structures.

[0122] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, the plurality of color LED structures have a same central axis.

[0123] 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 having a thickness in a range of 5 nm to 10 nm, and a thickness of each of the plurality of color LED structures does not exceed 300 nm.

[0124] In some exemplary embodiments of the micro-LED pixel unit or any combination of the foregoing 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).

[0125] Some exemplary embodiments provide a micro LED pixel unit, which includes: a semiconductor substrate; a light-emitting area, 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 area, 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 reflective cup surrounding the light-emitting area; and a refractive structure formed between the reflective cup and the light-emitting area.

[0126] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a micro lens is formed on a top surface of the refractive structure.

[0127] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a lateral dimension of the micro lens is not smaller than a lateral dimension of the light emitting area.

[0128] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective cup has a top opening area, and a lateral dimension of the micro lens is smaller than a lateral dimension of the top opening area.

[0129] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bottom dielectric layer is formed between the bottom of the reflective cup and the semiconductor substrate.

[0130] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing 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 reflective cup.

[0131] 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 of the reflective cup or the bottom of the reflective cup.

[0132] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a top of the refractive structure is higher than a top of the reflective cup.

[0133] 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.

[0134] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the reflective cup is a stepped reflective cup forming a cavity surrounding the light emitting area.

[0135] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the subcavities formed by the plurality of inclined surfaces have different sizes in a horizontal direction.

[0136] In some exemplary embodiments of a micro-LED pixel unit or any combination of the foregoing exemplary embodiments, each of the multiple color LED structures includes a corresponding extension portion extending from a side of the corresponding color LED structure, and the corresponding extension portion is electrically connected to the top electrode layer via a corresponding first contact via, and the bottom of each of the multiple color LED structures is electrically connected to the semiconductor substrate via a corresponding second contact via.

[0137] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light emitting area, formed on the semiconductor substrate, comprising 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 area, wherein each of the plurality of color LED structures comprises 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 reflective cup, surrounding the light emitting area, light emitted in a horizontal direction from a side wall of the light emitting layer of each of the plurality of color LED structures reaches the reflective cup and is reflected upward by the reflective cup, and the top of the reflective cup is higher than the top of the light emitting area.

[0138] In some exemplary embodiments of a micro LED pixel unit or any combination of the foregoing exemplary embodiments, a micro lens is formed over the light emitting area.

[0139] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a top of the reflective cup is higher than a top of the micro lens.

[0140] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a refractive structure is formed at the bottom of the micro lens and between the reflective cup and the light emitting area.

[0141] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bottom of the light emitting area is electrically connected to the semiconductor substrate.

[0142] Some exemplary embodiments provide a micro LED pixel unit, comprising: a semiconductor substrate; a light emitting area formed on the semiconductor substrate, comprising a plurality of color LED structures, wherein the bottom of each of the plurality of color LED structures is connected to a corresponding bonding metal layer in the light emitting area, wherein each of the plurality of color LED structures comprises 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 reflective cup surrounding the light emitting area, wherein the bottom of the floating reflective cup is located above the semiconductor substrate, and light emitted in a horizontal direction from a side wall of the light emitting layer of each of the plurality of color LED structures reaches the suspended floating reflective cup and is reflected upward by the suspended floating reflective cup.

[0143] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bottom of the floating reflector cup is higher than a top surface of a corresponding bonding metal layer of a bottom of one of the plurality of color LED structures.

[0144] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the floating reflector is stepped.

[0145] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a top of the floating reflective cup is higher than a top of the micro lens.

[0146] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a refractive structure is formed at the bottom of the micro lens between the floating reflective cup and the light emitting area.

[0147] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the floating reflector has a top opening area, and a lateral dimension of the micro lens is smaller than a lateral dimension of the top opening area.

[0148] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, a bottom dielectric layer is formed between the floating reflector cup and the semiconductor substrate.

[0149] 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 of the floating reflector cup or the bottom of the floating reflector cup.

[0150] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the stepped floating reflector cup forms a cavity surrounding the light emitting area.

[0151] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the material of the floating reflective cup includes metal.

[0152] 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, which is respectively formed at the bottom of each of the plurality of color LED structures.

[0153] In some exemplary embodiments of the micro LED pixel unit or any combination of the foregoing exemplary embodiments, the thickness of the reflective layer is in a range of 5 nm to 10 nm, and the thickness of each of the plurality of color LED structures does not exceed 300 nm.

[0154] The compact design of the multicolor LED device and system disclosed herein utilizes the lateral overlap of the light-emitting LED structure, thereby improving the luminous efficiency, resolution and overall performance of the LED display system. In addition, the manufacture of the multicolor LED display system can reliably and effectively form the LED structure pattern without using or retaining an additional substrate. In some cases, the design of the display device and system disclosed herein forms a microlens directly on the top of the multicolor LED device on the substrate by utilizing the consistency of the shape of the microlens material with the shape of the multicolor LED device, thereby greatly reducing the steps of microlens manufacturing and improving the efficiency of display panel structure formation. Reducing the viewing angle and reducing light interference improves the luminous efficiency, resolution and overall performance of the display system. Therefore, the implementation of the multicolor LED display system can meet the strict display requirements for AR and VR, head-up displays, displays for mobile devices, displays for wearable devices, high-definition small projectors and automotive displays compared to the use of conventional LEDs.

[0155] It should be noted that the various embodiments described above may be combined with any other embodiments described herein. The features and advantages described in the specification are not all-inclusive, and in particular, many additional features and advantages will be apparent to those of ordinary skill in the art from the drawings, the specification, and the claims. Furthermore, it should be noted that the language used in the specification is selected primarily for readability and instructional purposes, and is not selected to delineate or limit the subject matter of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0156] In order that the present disclosure can be understood in more detail, the present disclosure may be described in more detail by referring to the features of various embodiments, some of which are shown in the accompanying drawings. However, these drawings only illustrate the relevant features of the present disclosure and are therefore not to be considered restrictive, as the description may allow for other effective features.

[0157] Figure 1Ais a top view of a single pixel three-color LED device 100 according to some embodiments.

[0158] Figure 1B A single pixel three-color LED device 100 according to some embodiments is Figure 1A A cross-sectional view along the diagonal line 102 .

[0159] Figure 1C A single pixel three-color LED device 100 according to some embodiments is Figure 1A A cross-sectional view along the diagonal line 150.

[0160] Figure 2A A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A A cross-sectional view along the diagonal line 102 .

[0161] Figure 2B A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A A cross-sectional view along the diagonal line 150.

[0162] Figure 3A A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A A cross-sectional view along the diagonal line 102 .

[0163] Figure 3B A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A A cross-sectional view along the diagonal line 150.

[0164] Figure 4A is a top view of a layered planarized single pixel three-color LED device 400 according to some embodiments.

[0165] Figure 4B is a planarized single pixel tri-color LED device 400 according to some embodiments. Figure 4A A cross-sectional view along the diagonal line 402.

[0166] Figure 5 The single pixel three-color LED device 500 with a refractive structure according to some embodiments is Figure 1A A cross-sectional view along the diagonal line 102 .

[0167] Fig. 6A A single pixel three-color LED device 600 with a microlens on a reflective structure according to some embodiments Figure 1A A cross-sectional view along the diagonal line 102 .

[0168] Figure 6BA single pixel three-color LED device 600 having a microlens within the area formed by the reflective structure according to some embodiments Figure 1A A cross-sectional view along the diagonal line 102 .

[0169] Figure 6C A method of manufacturing a display panel having an integrated microlens array formed using top-down pattern transfer according to some embodiments.

[0170] Fig.6D A method of manufacturing a display panel having an integrated microlens array formed using top-down pattern transfer according to some embodiments.

[0171] Figure 7 is an edge of three single pixel tri-color LED devices 710, 720, and 730 located on substrate 104 according to some embodiments. Figure 1A A cross-sectional view 700 along a diagonal line such as 102 is shown.

[0172] Figure 8 The single pixel three-color LED device 800 with a stepped reflector according to some embodiments is Figure 4A A cross-sectional view of a diagonal line such as 402 .

[0173] Fig. 9 The single pixel three-color LED device 900 with a floating reflector according to some embodiments Figure 4A A cross-sectional view of a diagonal line such as 402 .

[0174] Fig. 10A is a circuit diagram of a matrix of single pixel three-color LED devices 1000 according to some embodiments.

[0175] Fig. 10B is a circuit diagram of a matrix of single pixel three-color LED devices 1000 according to some embodiments.

[0176] Fig.11 is a top view of a micro LED display panel 1100 according to some embodiments.

[0177] According to common practice, the various features illustrated in the drawings may not be drawn to scale. Therefore, for clarity, the sizes of various features may be arbitrarily expanded or reduced. In addition, some drawings may not depict all components of a given system, method, or device. Finally, the same reference numerals may be used to represent similar features throughout the specification and drawings. DETAILED DESCRIPTION

[0178] Numerous details are described herein in order to provide a thorough understanding of the example embodiments shown in the accompanying drawings. However, some embodiments may be practiced without many of the specific details, and the scope of the claims is limited only by those features and aspects specifically detailed in the claims. In addition, well-known methods, components, and materials are not described in detail so as not to unnecessarily obscure the relevant aspects of the embodiments described herein.

[0179] 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 there are two LED structures in a single-pixel multicolor LED device, light of two colors and a mixed color of the two colors can be emitted from the single-pixel multicolor LED device. When there are three LED structures in a single-pixel multicolor LED device, light of three colors and a mixed color of the three colors can be emitted from the single-pixel multicolor LED device.

[0180] 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 light emitted from the sidewalls of each LED structure upward. 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, light emitted from a single-pixel multicolor LED device is a combination of light emitted from the sidewalls and the top surface of each LED structure within the single-pixel multicolor LED device, for example, in a certain proportion, light emitted from the sidewalls accounts for about 20% to 100% of the light emitted by the single-pixel multicolor LED device.

[0181] Figure 1A is a top view of a single pixel three-color LED device 100 according to some embodiments.

[0182] Figure 1B is a single pixel three-color LED device 100 according to some embodiments. Figure 1A A cross-sectional view along the diagonal line 102 .

[0183] Figure 1C is a single pixel three-color LED device 100 according to some embodiments. Figure 1A A cross-sectional view along the diagonal line 150.

[0184] Diagonal lines 102 and 150 each pass through the center of a single pixel tri-color LED device 100. Diagonal lines 102 and 150 are orthogonal to each other. In some embodiments, tri-color LED device 100 includes substrate 104. For convenience, "upward" is used to mean away from substrate 104, "downward" means toward substrate 104, and other directional terms such as top, bottom, above, below, directly below, below, etc. are also interpreted accordingly. Support substrate 104 is a substrate on which an array of individual drive circuits 106 are prepared. In some embodiments, the drive circuit can also be located in one of the layers above substrate 104, or above micro tri-color LED structure 100. Each drive circuit is a pixel driver 106. In some cases, drive circuit 106 is a thin film transistor pixel driver or a silicon CMOS pixel driver. In one embodiment, substrate 104 is a Si substrate. In another embodiment, 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 drive circuit 106 forms each pixel driver to control the operation of each individual pixel three-color LED device 100. The circuit on the substrate 104 includes contacts for each individual drive circuit 106 and ground contacts. Figure 1A , 1B As shown in 1C, each micro tri-color 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 the ground (i.e., the common electrode), such as 116, 120 and 140.

[0185] In some embodiments, the N electrode (or N electrode contact pad) and its connecting parts, 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 of the above materials. In some embodiments, the N electrode (or N electrode contact pad) and its connecting parts, such as 116, 120 and 140, are made of non-transparent or transparent conductive materials, and in a preferred embodiment, are made of transparent conductive materials. In some embodiments, the P electrode (or P electrode contact pad) and its connecting parts, such as 126, 152, are made of materials such as graphene, ITO, AZO or FTO or any combination of the above materials. In some embodiments, the P electrode (or P electrode contact pad) and its connecting parts, such as 126, 152, are made of non-transparent or transparent conductive materials, and in a preferred embodiment, are made of transparent conductive materials. In some embodiments, the positions of the P electrode (or P electrode contact pad) and its connecting parts and the N electrode (or N electrode contact pad) and its connecting parts can be switched.

[0186] Although some features are described herein using the term "layer", it should be understood that these features are not limited to a single layer, but may include multiple sub-layers. In some cases, a "structure" may take the form of a "layer".

[0187] In some embodiments, three LED structures including LED light-emitting layers 112 , 130 , and 136 , respectively, form a stacked structure. 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 .

[0188] Typically, an LED light emitting layer includes a PN junction having a p-type region / layer and an n-type region / layer, and an active layer between the p-type region / layer and the n-type region / layer.

[0189] In some embodiments, 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.

[0190] In some embodiments, the light emitted by the red LED light emitting layer 112 can propagate horizontally toward the sidewalls of the red LED light emitting layer 112, and then be reflected upward by a reflective element such as 146 and / or 148 as described below, and be emitted at the top surface of the single pixel three-color LED device 100. As described below, a reflective layer 109 is disposed below the red LED light emitting layer 112, and a reflective layer 115 is disposed above the red LED light emitting layer 112. The light emitted by the red LED light emitting layer 112 is reflected toward the sidewalls of the red LED light emitting layer 112 between the two reflective layers 109 and 115.

[0191] 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 upward by a reflective element such as 146 and / or 148 as described below, and be emitted at the top surface of the single pixel three-color LED device 100. As described below, a reflective layer 127 is disposed below the green LED light emitting layer 130, and a reflective layer 133 is disposed 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.

[0192] In some embodiments, light emitted by 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 upward by a reflective element such as 146 and / or 148 as described below, and be 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.

[0193] In some embodiments, light emitted by the red LED light emitting layer 112 can propagate vertically through the green LED light emitting layer 130 and then be emitted from the three-color LED device 100 through the blue LED light emitting layer 136. In some embodiments, light emitted by the green LED light emitting layer 130 can propagate through the blue LED light emitting layer 136 to be emitted from the three-color LED device 100. In the case of vertical light transmission, in some preferred embodiments, the top reflective layers above each light emitting layer, such as 115 and 133, are not included in the three-color LED device 100.

[0194] In some embodiments, LED light emitting layers such as 112, 130, and 136 include many 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 micro-LEDs include GaN-based UV / blue / green micro-LEDs, AlInGaP-based red / orange micro-LEDs, and GaAs or InP-based infrared (IR) micro-LEDs.

[0195] In some embodiments, each LED structure in the stacked LED structure can be controlled separately to produce its own light. In some embodiments, the mixed light emitted by the top LED epitaxial layer can change the color of a single pixel in a small footprint on a display panel due to the simultaneous operation of all LED epitaxial layers in the tri-color LED device 100.

[0196] In some embodiments, the color of light emitted by each LED structure included in the same device is not limited to red, green and blue according to the design of the LED device 100. For example, a suitable color can be selected from a range of different color lights with wavelengths of 380nm to 700nm in the visible light range. In some embodiments, the LED structure can also emit other color lights in the invisible range such as ultraviolet rays and infrared rays.

[0197] In some embodiments, when vertical light emission is combined with horizontal light emission, for example, the three color choices from bottom to top may be red, green, and blue. In another embodiment, the three color choices from bottom to top may be infrared, orange, and ultraviolet. In some embodiments, the wavelength of light emitted by the LED structure on a certain layer of the device 100 is longer than the wavelength of light emitted by the LED structure on the layer above the current layer. 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.

[0198] In some embodiments, when emitting light horizontally or when the portion emitting light horizontally is greater than the portion emitting light vertically from the top surface of the LED device 100, each of the LED light-emitting layers 112, 130, and 136 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 100 but is directly emitted from the edge or sidewall of the current light-emitting layer, light propagation loss can be reduced and light-emitting efficiency can be improved. For example, compared with vertically emitting LED devices, horizontally emitting LED devices can increase 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%.

[0199] In some embodiments, the bottom red LED light emitting layer 112 is bonded to the substrate 104 through the metal bonding layer 108. The metal bonding layer 108 can 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, and serves as a P electrode. In some embodiments, the thickness of the metal bonding layer 108 is about 0.1 microns to 3 microns. In a preferred embodiment, the thickness of the metal bonding layer 108 is about 0.3 μm. 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 in the LED device 100. The 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 a combination thereof. For example, if Au-Au bonding is selected, the two layers of Au 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 thickness of the two Au layers is approximately the same, under high pressure and high temperature, the Au on the two layers diffuse mutually to bond the two layers together. Eutectic bonding, hot pressing bonding and transient liquid phase (TLP) bonding are exemplary techniques that can be used.

[0200] In some embodiments, the metal bonding layer 108 may also act as a reflector to reflect light emitted from the LED structure above.

[0201] 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 is a conductive transparent layer such as an indium tin oxide (ITO) layer that is transparent to the light emitted by the LED device 100, and is formed between the red LED light emitting layer 112 and the metal bonding layer 108 to improve conductivity and light transmittance.

[0202] exist Figures 1A to 1C In some embodiments not shown in the figure, 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 can be, for example, Figure 1CA metal layer or a conductive transparent layer, such as an ITO layer, for improving conductivity and transmittance is shown formed between the red LED light emitting layer 112 and the N-electrode contact pad 116. In some embodiments, the N-electrode contact pad 116 is made of graphene, ITO, AZO or FTO or any combination thereof.

[0203] In some embodiments, a reflective layer 109 is disposed between the conductive layer 110 and the metal bonding layer 108 below the red LED light emitting layer 112 , and a reflective layer 115 is disposed between the conductive layer 114 and the bonding layer 156 above the red LED light emitting layer 112 .

[0204] In some embodiments, the red LED light emitting layer 112 has an extension portion 164 on one side thereof relative to other layers above. Figure 1C In some embodiments, the extension portion 164 extends with the conductive layers 110 and 114. In some embodiments, the extension portion 164 extends 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 portion of the conductive layer 114 above the extension portion 164.

[0205] In one method, the red LED light emitting layer 112 is grown on another separate substrate (called an 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 in .

[0206] In some embodiments, the red LED light emitting layer 112 is used to form a red micro-LED. Examples of red LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the red LED light emitting layer 112 may include a layer of P-type GaP / P-type AlGaInP light emitting layer / AlGaInP / N-type AlGaInP / N-type GaAs. In some embodiments, the P-type layer is typically Mg-doped, and the N-type layer is typically Si-doped. In some examples, the thickness of the red LED light emitting layer is approximately 0.1 microns to 5 microns. In a preferred embodiment, the thickness of the red LED light emitting layer is approximately 0.3 microns.

[0207] 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 .

[0208] 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 metal bonding layer 108. In some embodiments, bonding layer 156 can also be used as a reflector to reflect light emitted by the LED structure above.

[0209] In some embodiments, when vertical propagation is used, the bonding layer 156 is transparent to the light emitted by the micro-LED 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 borophosphosilicate glass (BPSG) or any combination thereof. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive BCL-1200 from Micro Resist, or any combination thereof. In some embodiments, the transparent bonding layer can facilitate the passage of light emitted by the layer below the bonding layer.

[0210] In some embodiments, 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 the conductive layer 128. In some embodiments, the conductive layer 128 for electrode connection is formed at the bottom of the green LED light emitting layer 130. In some embodiments, as Figure 1A and 1B As shown, the conductive layer 128 may be a conductive transparent layer such as an ITO layer or a metal layer for improving conductivity and transmittance, and is formed between the green LED light emitting layer 130 and the P-electrode contact pad 126 .

[0211] In some embodiments, the conductive layer 128 has an extension portion 128-1 on one side thereof relative to other layers above. Figure 1B In some embodiments, the extension portion 128-1 extends together with all layers below the conductive layer 128 in the LED device 100. In some embodiments, the green LED light emitting layer 130 is electrically connected to the P-electrode contact pad 126 through the extension portion 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.

[0212] 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. The P-electrode contact pad 126 extends from its contact with the drive circuit 106 to its contact with the conductive layer 128 through a via or channel in the insulating layer 174. The P-electrode contact pad 126 does not contact other layers in the LED device 100.

[0213] 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.

[0214] In some embodiments, Figure 1C As shown in FIG, 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.

[0215] like Figure 1C As shown, in some embodiments, the green LED light emitting layer 130 has an extension portion 166 on one side thereof. In some embodiments, the extension portion 166 extends together with the conductive layers 128 and 132 and all other layers below the conductive layer 128. In some embodiments, the extension portion 166 is electrically connected to the N-electrode contact pad 120 through the extension portion of the conductive layer 132 above the extension portion 166.

[0216] 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 .

[0217] In some embodiments, a reflective layer 127 is disposed between the conductive layer 128 and the bonding layer 156 below the green LED light emitting layer 130 , and a reflective layer 133 is disposed between the conductive layer 132 and the bonding layer 160 above the green LED light emitting layer 130 .

[0218] In one method, the green LED light emitting layer 130 is grown on another separate substrate (called an 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 in .

[0219] In some embodiments, the green LED light emitting layer 130 is used to form a green micro-LED. Examples of green LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the green LED light emitting layer 130 may include 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 microns to 5 microns. In a preferred embodiment, the thickness of the green LED light emitting layer is approximately 0.3 microns.

[0220] 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 .

[0221] In some embodiments, without including extended portions such as 164, 166 and the portion below 128-1 of conductive layer 128, the first LED structure, e.g., a red LED structure, and the second LED structure, e.g., a green LED structure, have the same central axis. In some embodiments, without including extended portions such as 164, 166 and the portion below 128-1 of conductive layer 128, the first LED structure and the second LED structure are aligned along the same central axis.

[0222] 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 the 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 can also be used as a reflector to reflect light emitted by the LED structure above.

[0223] In some embodiments, when vertical propagation is used, bonding layer 160 is transparent to light emitted by LED device 100. In some embodiments, bonding layer 160 is made of a dielectric material such as a solid inorganic material or a plastic material, as described above for bonding layer 156. In some embodiments, a transparent bonding layer can facilitate the passage of light emitted by layers below the bonding layer.

[0224] In some embodiments, 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 the 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, as Figure 1A and 1B As shown, the conductive layer 134 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 P-electrode contact pad 152 to improve conductivity and transmittance.

[0225] In some embodiments, the conductive layer 134 has an extension portion 134-1 on one side thereof relative to other layers above. Figure 1B In some embodiments, the extension portion 134-1 extends together with all layers below the conductive layer 134 in 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 portion 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.

[0226] 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. The P-electrode contact pad 152 extends from its contact with the drive circuit 106 to its contact with the conductive layer 134 through a via or channel in the insulating layer 174. The P-electrode contact pad 152 does not contact other layers in the LED device 100.

[0227] 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 or a metal layer such as an ITO layer, formed between the blue LED light emitting layer 136 and the N electrode contact pad 140 to improve conductivity and 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 of the above. 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 an integral element as a common N electrode.

[0228] In some embodiments, Figure 1B As shown in FIG. 1 , 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 .

[0229] 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 .

[0230] In some embodiments, the top electrode elements such as N-electrode pad 140 are connected by electrical connection elements below the optical isolation structures such as 146, 148, 170, and 172. In some embodiments, the top electrodes are connected by electrical connection elements embedded in substrate 104. In one example, the top electrode 140 is connected by electrical connection elements located above insulating layer 174 and below the optical isolation structures such as 146, 148, 170, and 172.

[0231] In some embodiments, a reflective layer 135 is provided between the conductive layer 134 and the bonding layer 160 below the blue LED light emitting layer 136. In some embodiments, an optional reflective layer 139 ( Figures 1A-1C not shown).

[0232] In one method, the blue LED light emitting layer 136 is grown on another separate substrate (called an 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 in .

[0233] In some embodiments, the blue LED light emitting layer 136 is used to form a blue micro-LED. Examples of blue LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the blue LED light emitting layer 136 may include 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 blue LED light emitting layer is approximately 0.1 microns to 5 microns. In a preferred embodiment, the thickness of the blue LED light emitting layer is approximately 0.3 microns.

[0234] In some embodiments, the blue LED structure includes a reflective layer 135 , a conductive layer 134 , a blue LED light 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 .

[0235] In some embodiments, without including an extension such as 166 and the lower portion of 134-1 of conductive layer 134, the second LED structure, e.g., a green LED structure, and the third LED structure, e.g., a blue LED structure, have the same central axis. In some embodiments, without including an extension such as 166 and the lower portion of 134-1 of conductive layer 134, the first LED structure and the second LED structure are aligned along the same central axis.

[0236] In some embodiments, the N electrode 140 covers the top of the three-color LED device 100. In some embodiments, the N electrode 140 is connected to the N electrode (at the top) of the adjacent three-color LED device via some electrical connection elements. Figures 1A-1C ), as a common electrode.

[0237] In some embodiments, each conductive layer 110, 114, 128, 132, 134, and 138 has a thickness of about 0.01 micrometers to 1 micrometer. In some cases, each conductive layer 110, 114, 128, 132, 134, and 138 is typically deposited on the respective corresponding epitaxial layer by a vapor deposition process, such as electron beam evaporation or sputtering deposition, before any bonding process with the next epitaxial layer is performed. In some examples, the conductive layer is used to maintain good conductivity of the electrode connection, and in some cases, it is also used to improve the optical properties of the LED device, such as reflectivity or transmittance.

[0238] 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. Figures 1A-1C In some embodiments, the additional dielectric layer has a thickness of 20 nanometers to 2 micrometers. In a preferred embodiment, the additional dielectric layer has a thickness of about 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 (in the embodiment of FIG. 1 ). Figures 1A-1C 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 about 100 nanometers.

[0239] In some embodiments, to improve the light emission efficiency from the three-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 three-color LED device 100. In some embodiments, the optical isolation structures such as 146, 148, 170, and 172 are made of a dielectric material such as SiO2.

[0240] As in Figure 1A As shown from a top view in FIG. 1 , in some embodiments, the three-color LED device 100 has a circular shape. In some embodiments, optical isolation structures such as 146, 148, 170, and 172 are connected as a whole and form a circular side wall around the three-color LED device 100. In some embodiments, the optical isolation structure forms a reflective cup described in further detail below. In some embodiments, the three stacked LED structures within the three-color LED device 100 are also circular in shape. In some embodiments, the three-color LED device 100 can be in other shapes, such as rectangular, square, triangular, trapezoidal, polygonal. In some embodiments, optical isolation structures such as 146, 148, 170, and 172 are connected as a whole and form a side wall around the three-color LED device 100 in other shapes such as rectangular, square, triangular, trapezoidal, polygonal.

[0241] 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 may refer to a surface that is not perpendicular to the top surface or the bottom surface of the corresponding LED light-emitting layer. In some embodiments, the angle between the inclined side wall and the bottom surface of the corresponding LED light-emitting layer is less than 90 degrees. In some embodiments, the bonding layers 108, 156, and 160 also have inclined side surfaces. The inclined side surfaces can facilitate the connection of different connecting elements to each LED light-emitting layer, prevent the connection elements from being disconnected due to sudden changes in angles, and enhance the overall stability of the device.

[0242] In some embodiments, the light propagation efficiency of the multicolor LED device changes as the angle of the inclined side surface of the LED light emitting layer relative to the surface normal of the substrate 104 changes. In some embodiments, the light propagation efficiency of the multicolor LED device increases as the angle of the inclined side surface of the LED light emitting layer relative to the normal of the substrate 104 surface increases. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the substrate 104 surface is ±5 degrees and when the optical isolation structure such as 146, 148, 170 and / or 172 is not a reflective 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 normal of the substrate 104 surface is ±15 degrees and when the optical isolation structure such as 146, 148, 170 and / or 172 is not a reflective cup as described below, the luminous efficiency of the multicolor LED device is 2.7%. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the surface of the substrate 104 is at (for example, 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 not a reflective cup as described below, the luminous efficiency of the multi-color LED device is equal to or very close to 56.4%.

[0243] In contrast, the implementation of the reflective cup structure as described in further detail below improves the light propagation efficiency of the multi-color LED device. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the substrate 104 surface is ±5 degrees and when the optical isolation structure such as 146, 148, 170 and / or 172 is a reflective cup as described below, the luminous efficiency of the multi-color LED device is 0.65%, that is, an increase of 104.6% compared to the LED device without the reflective cup. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the substrate 104 surface is ±15 degrees and when the optical isolation structure such as 146, 148, 170 and / or 172 is a reflective cup as described below, the luminous efficiency of the multi-color LED device is 6.65%, that is, an increase of 144.4% compared to the LED device without the reflective cup. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the surface of the substrate 104 is at (for example, 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 reflective cup as described below, the luminous efficiency of the multi-color LED device is equal to or very close to 66.65%, that is, an increase of 18.4% compared to the LED device without a reflective cup.

[0244] In some embodiments, a reflective layer is formed above and below each LED light emitting layer to improve light transmission efficiency. 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 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.

[0245] 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, in the presence of the conductive layer 128, 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, in the presence of the conductive layer 132, the reflective layer 133 is formed between the bonding layer 160 and the conductive layer 132.

[0246] 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, in the presence of the conductive layer 134, the reflective layer 135 is formed between the bonding layer 160 and the conductive layer 134. In some embodiments, an optional reflective layer 139 ( Figure 1B-1C In some embodiments, where conductive layer 138 is present, an optional reflective layer 139 is formed between N-electrode pad 140 and conductive layer 138, while still allowing conductive layer 138 to be electrically connected to N-electrode pad 140, for example, through a conductive path.

[0247] In some embodiments, the material reflectivity of the reflective layers 109, 115, 127, 133, 135, and 139 is high, especially for light emitted by a single pixel three-color LED device 200. For example, the reflectivity of the reflective layers 109, 115, 127, 133, 135, and 139 is higher than 60%. In another example, the reflectivity of the reflective layers 109, 115, 127, 133, 135, and 139 is higher than 70%. In yet another example, the reflectivity of the reflective layers 109, 115, 127, 133, 135, and 139 is higher than 80%.

[0248] In some embodiments, the material of the reflective layers 109, 115, 127, 133, 135 and 139 is selected from one or more of the following metals: Rh, Al, Ag and Au. In some embodiments, any one of the reflective layers 109, 115, 127, 133, 135 and 139 may include at least two sub-layers with different refractive indices. Each sub-layer also has a high reflectivity such as higher than 60%, 70% or 80%.

[0249] In some embodiments, each reflective layer, such as 109, 115, 127, 135, and 139, is coated on both sides of each of the light-emitting layers, such as 112, 130, and 136, or, in the case of a conductive layer, is coated on both sides of the conductive layers 110, 114, 128, 132, 134, and 138 before bonding. In some cases, the thickness of each of the reflective layers, such as 109, 115, 127, 133, 135, and 139, is about 2 nanometers (nm) to 5 microns. In some embodiments, the thickness of each of the reflective layers, such as 109, 115, 127, 133, 135, and 139, is equal to or less than 1 micron. In some preferred embodiments, the thickness of each of the reflective layers, such as 109, 115, 127, 133, 135, and 139, is about 5 nanometers (nm) to 10 nm.

[0250] In some embodiments, any of the reflective layers such as 109, 115, 127, 133, 135, and 139 includes a distributed Bragg reflector (DBR) structure. For example, any of the reflective layers such as 109, 115, 127, 133, 135, and 139 is formed by alternating multiple layers or multiple layers of different materials with different refractive indices. In some cases, each layer boundary of the DBR structure causes partial reflection of the light wave. Reflective layers such as 109, 115, 127, 133, 135, and 139 can be used to reflect some 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 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 transmission of light of different wavelengths can be achieved.

[0251] In some embodiments, any of the reflective layers such as 109, 115, 127, 133, 135 and 139 further includes a transparent layer on one of the high reflectivity sub-layers. For example, the transparent layer formed on either or both sides of the reflective layers such as 109, 115, 127, 133, 135 and 139 is preferably selected from one or more of ITO and SiO2.

[0252] In some embodiments, each of the reflective layers 109 and 115 for red LEDs includes multiple layers of Au or / and indium tin oxide (ITO).

[0253] In some embodiments, each of the reflective layers 109 and 115 for the red LED structure has a low absorbance (e.g., equal to or less than 25%) for light generated by a different layer of the tri-color LED device 100. In some embodiments, each of the reflective layers 109 and 115 for the red LED structure has a 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.

[0254] In one example, the following DBR structure shown in Table 1 is used to reflect green light from a green LED:

[0255] Table 1: DBR layer structure for green LED reflector layer.

[0256] In some embodiments, each of the reflective layers 127 and 133 for the green LED structure has a low absorbance (e.g., equal to or less than 25%) for light generated by a different layer of the three-color LED device 100. In some embodiments, each of the reflective layers 127 and 133 for the green LED structure has a 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.

[0257] In one example, the following DBR structure shown in Table 2 is used to reflect blue light from a blue LED:

[0258] Table 2: DBR layer structure for blue LED reflector layer.

[0259] In some embodiments, each of the reflective layers 135 and optional 139 for the blue LED structure has a low absorbance (e.g., equal to or less than 25%) to light generated by a different layer of the tri-color LED device 100. In some embodiments, the reflective layer 135 for the blue LED structure has a high reflectivity (e.g., equal to or greater than 75%) to light generated above the current reflective layer 135 or between the current reflective layers 135 and 139, such as blue light.

[0260] Figure 2A A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A In some embodiments, a single pixel three-color LED device 100 has a cross-sectional view along a diagonal line 102. Figure 1A , 1B A structure similar to the single-pixel three-color LED device 100 shown in 1C is added with a planarization layer 176 covering the single-pixel three-color LED device 100.

[0261] Figure 2B A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A In some embodiments, a single pixel three-color LED device 100 has a cross-sectional view along a diagonal line 150. Figure 1A , 1B A structure similar to the single-pixel three-color LED device 100 shown in 1C is added with a planarization layer 176 covering the single-pixel three-color LED device 100.

[0262] In some embodiments, a planarization layer such as 176 is transparent to light emitted by micro-LED 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 borophosphosilicate glass (BPSG), or any combination of the above. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive BCL-1200 from Micro Resist, or any combination of the above. In some embodiments, the planarization layer can facilitate the passage of light emitted by micro-LED 100.

[0263] In some embodiments, planarization layer 176 has the same height as optical isolation structures such as 146, 148, 170, and 172 relative to the surface of substrate 104. For example, planarization layer 176 covers the entire single pixel three-color LED device 100 and the sidewalls of the optical isolation structures. Planarization layer 176 is on the same plane as the top surface of the optical isolation structures.

[0264] Figure 3A A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A In some embodiments, a single pixel three-color LED device 100 has a cross-sectional view along a diagonal line 102. Figure 1A , 1B A structure similar to the single pixel three-color LED device 100 shown in 1C is added with a planarization layer 178 covering the single pixel three-color LED device 100.

[0265] Figure 3B A single pixel three-color LED device 100 with planarization features according to some embodiments is shown along Figure 1A In some embodiments, a single pixel three-color LED device 100 has a cross-sectional view along a diagonal line 150. Figure 1A , 1B A structure similar to the single pixel three-color LED device 100 shown in 1C is added with a planarization layer 178 covering the single pixel three-color LED device 100.

[0266] In some embodiments, planarization layer 178 has the same height as the top electrode element, such as 140. Planarization layer 178 is 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 just on top of planarization layer 178. Planarization layer 178 is 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 three-color LED device 100 and a portion of the optical isolation structure sidewalls, such as 146, 148, 170, and 172.

[0267] With Figures 1A-1C The top electrode elements such as N electrode pad 140 shown are connected differently through electrical connection elements such as 146, 148, 170 and 172 below the optical isolation structure. Figure 2A-2B, 3A-3B, the top electrode element such as N electrode pad 140 is connected by electrical connection elements at least on the sidewalls of the optical isolation structures such as 146, 148, 170 and 172. In some embodiments, N electrode pad 140 is fixed by or on the surface of the optical isolation structures such as 146, 148, 170 and 172. The top electrode structure can simplify the manufacturing process, especially with a planarized layer, making the single pixel three-color LED device 100 compact.

[0268] In some embodiments, the insulating layer can be deposited on a single pixel multi-color LED device by being deposited on each LED light emitting layer and other layers such as a conductive layer and a reflective layer. A planarization process is then performed to flatten the surface of the insulating layer in which the single pixel multi-color LED device is embedded. Vias for electrical connections are also formed in each planarization layer. Compared to insulating layers that are not planarized using other processes, the features and layers within the planarized LED structure are better protected and less susceptible to external destructive forces. In addition, the planarized surface can provide light propagation efficiency by reducing deflections caused by uneven surfaces.

[0269] In some embodiments, a three-color LED structure is formed by dry etching and wet etching, and the axes of the LED structures of different colors are vertically aligned with each other. In some embodiments, the LED structures of different colors share the same axis.

[0270] In some embodiments, each of the LED structures of different colors forms a pyramid shape or a shape with a trapezoidal cross section. Each layer has a narrower width or a smaller area than the layer below it. In this case, the width or area is measured by the size of a plane parallel to the surface of the substrate 104.

[0271] In some embodiments, each of a plurality of LED structures of different colors is bonded together by a bonding layer that covers only the area of ​​the LED structure without an extension beyond the area of ​​the LED structure, and the entire multi-color LED device forms a pyramid (or inverted cone) shape or a shape with a trapezoidal cross-section (as shown in FIGS. 1-3 ). In some embodiments, the lateral dimension of the bottom LED structure, such as a red LED structure, may be the longest, and the lateral dimension of the top LED structure, such as a blue LED structure, may be the shortest. The pyramid shape may be formed naturally from the bottom up as the various layers within the LED device are etched and patterned. The pyramidal structure may improve the electrical connection between individual LED structures and with electrodes, and simplify the manufacturing process. For example, the electrode connection elements in each layer are exposed in each layer for easy connection.

[0272] In some embodiments, the bottom layer, such as the metal bonding layer 108, has a lateral dimension of about 1 micron to 500 microns. In a preferred embodiment, the lateral dimension of the metal bonding layer 108 at the bottom of the multi-color LED device is about 1.75 microns. In some embodiments, the vertical height of the multi-color LED device is about 1 micron to 500 microns. In a preferred embodiment, the vertical height of the multi-color LED device is about 1.9 microns. In a preferred embodiment, the lateral dimension of the conductive layer 138 at the top of the multi-color LED device is about 1.0 micron.

[0273] In some embodiments, the cross-sectional aspect ratio of the layers of the tri-color LED device remains substantially the same as the lateral dimensions of the same layers vary. For example, where the lateral dimension of the patterned epitaxial layer is 5 microns, the thickness of the patterned epitaxial layer is less than one micron. In another example, where 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 cross-section of the epitaxial layer and other layers is less than 1 / 5 of the thickness / width.

[0274] The shape of the LED device is not limited. In some other embodiments, the cross-sectional shape of the three-color LED device can be other shapes, such as an inverted trapezoid, a semi-ellipse, a rectangle, a parallelogram, a triangle or a hexagon.

[0275] 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 patterning 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 three-color LED device 100, including conductive layers 110, 114, 128, 132, 134, and 138.

[0276] In some embodiments, blue LED light emitting layer 136 and 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 C12 and BC13 etching gases.

[0277] In some embodiments, the bonding layer including 160 and 156 is patterned using photolithography and etching. In some cases, the etching method used to form the patterning is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases.

[0278] In some embodiments, the reflective layer including 109, 115, 127, 133, 135 and 139 is patterned using photolithography and etching. In some cases, the etching method used to pattern the reflective layer, especially the DBR layer, is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases or ion beam etching (IBE) using Ar gas.

[0279] 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 C12 and HBr etching gases.

[0280] 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, for example, inductively coupled plasma (ICP) etching using C12 / BC13 / Ar etching gas, or ion beam etching (IBE) using Ar gas.

[0281] In some embodiments, after each of the LED device structures is patterned, an insulating layer such as 174, 176, 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 similar composition to SiO2 is formed after curing a layer such as SOG at high temperature. In some embodiments, the insulating layer is made of a material having a thermal coefficient similar to the thermal coefficient of the layers below the insulating layer. Then, the surface of the insulating layer such as 176 and 178 is smoothed or planarized by related methods such as chemical mechanical polishing as understood by those of ordinary skill in the art.

[0282] In some embodiments, the insulating layers such as 176 and 178 after planarization are patterned using photolithography and etching to expose electrode contact areas. In some cases, the etching method used to form the patterning is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2.

[0283] In some embodiments, a P-electrode or anode metal pad is deposited at a suitable location of the patterned LED structure, such as on one side and / or in a via within a planarized insulating layer, using vapor deposition or by other deposition methods to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0284] In some embodiments, a separate N-electrode or cathode metal pad is deposited using vapor deposition or by other deposition methods at a suitable location of the patterned LED structure, such as on the side / top and / or in a via within a planarized insulating layer to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0285] Figure 4A is a top view of a layered planarized single pixel three-color LED device 400 according to some embodiments.

[0286] Figure 4B is a planarized single pixel tri-color LED device 400 according to some embodiments. Figure 4A 4. A cross-sectional view of a three-color LED device 400 along a diagonal line 402. The diagonal line passes through the center of a single pixel three-color LED device 400.

[0287] Compared with the embodiment depicted in FIGS. 1-3 , Figure 4A-4B The main difference of the embodiment is that each of the LED structures of different colors is embedded in a corresponding planarized insulating layer, and the planarized insulating layers with the LED structures inside are bonded together via some bonding layers.

[0288] In some embodiments, the tri-color LED device 400 includes a substrate 404. For convenience, "upward" is used to mean away from the substrate 404, and "downward" means toward the substrate 404, and other directional terms such as top, bottom, above, below, directly below, below, etc. are also interpreted accordingly. The support substrate 404 is a substrate on which the array of individual drive circuits 406 are prepared. In some embodiments, the drive circuits can also be located in one of the layers above the substrate 404, or above the micro tri-color LED structure 400. Each drive circuit is a pixel driver 406. In some cases, the drive 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 microns thick. The drive circuits 406 form individual pixel drivers to control the operation of each individual pixel tri-color LED device 400. The circuitry on the substrate 404 includes contacts for each individual driver circuit 406 and a ground contact. Figure 4A and Figure 4BAs shown, each micro tri-color LED structure 400 also has two types of contacts: P electrodes or anodes such as 450 (or 408), 452 and merged portions 422, 424 and 426 connected to the pixel driver; and N electrodes or cathodes such as 440, 442, 444 and merged portions 416, 418 and 420 connected to the ground (i.e., the common electrode).

[0289] In some embodiments, the N electrode (or N electrode contact pad) and its connecting parts, such as 440, 442, 444 and the merged parts 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 parts, such as 440, 442, 444, and the merged parts 416, 418 and 420 are made of non-transparent or transparent conductive materials, and in a preferred embodiment, are made of transparent conductive materials. In some embodiments, the P electrode (or P electrode contact pad) and its connecting parts, such as 450, 452, and the merged parts 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 parts, such as 450, 452 and the merged parts 422, 424 and 426, are made of non-transparent or transparent conductive materials, and in a preferred embodiment, are made of transparent conductive materials. In some embodiments, the positions of the P electrode (or P electrode contact pad) and its connecting parts and the N electrode (or N electrode contact pad) and its connecting parts can be switched.

[0290] Typically, an LED light emitting layer includes a PN junction having a p-type region / layer and an n-type region / layer, and an active layer between the p-type region / layer and the n-type region / layer.

[0291] In some embodiments, 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 upward by a reflective element such as 446 and / or 448 as described below, and be emitted at the top surface of the single pixel tri-color LED device 400. As described below, a reflective layer 409 is disposed below the red LED light emitting layer 412, and a reflective layer 415 is disposed 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.

[0292] 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 upward by a reflective element such as 446 and / or 448 as described below, and be emitted at the top surface of the single pixel three-color LED device 400. As described below, a reflective layer 427 is disposed below the green LED light emitting layer 430, and a reflective layer 433 is disposed 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.

[0293] In some embodiments, light emitted by 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 upward by a reflective element such as 446 and / or 448 as described below, and be emitted at the top surface of the single pixel tri-color LED device 400. As described below, a reflective layer 435 is disposed 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.

[0294] 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 three-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 three-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 three-color LED device 400.

[0295] In some embodiments, LED light emitting layers such as 412, 430, and 436 include many 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 micro-LEDs include GaN-based UV / blue / green micro-LEDs, AlInGaP-based red / orange micro-LEDs, and GaAs or InP-based infrared (IR) micro-LEDs.

[0296] In some embodiments, each LED structure in the stacked LED structure can be controlled separately to produce its own light. In some embodiments, the mixed light emitted by the top LED epitaxial layer can change the color of a single pixel in a small footprint on the display panel due to the simultaneous operation of all LED epitaxial layers in the tri-color LED device 400.

[0297] In some embodiments, according to the design of LED device 400, the color of light emitted by each LED structure 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 color lights with wavelengths of 380nm to 700nm in the visible light range. In some embodiments, the LED structure can also emit other color lights from the invisible range such as ultraviolet rays and infrared rays.

[0298] In some embodiments, when vertical light emission is combined with horizontal light emission, for example, the three color choices from bottom to top may be red, green, and blue. In another embodiment, the three color choices from bottom to top may be infrared, orange, and ultraviolet. In some embodiments, the wavelength of light emitted by the LED structures on one layer of the device 400 is longer than the wavelength of light emitted by the LED structures on the layer above the current layer. 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.

[0299] In some embodiments, when emitting light horizontally or when the portion emitting light horizontally is greater than the portion emitting light vertically 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 emission is that since the emitted light does not need to pass through other upper layers of the LED device 400 but is directly emitted from the edge or sidewall of the current light-emitting layer, light propagation loss can be reduced and light-emitting efficiency can be improved. For example, compared with vertically emitting LED devices, horizontally emitting LED devices can increase 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%.

[0300] In some embodiments, the bottom red LED light emitting layer 412 is bonded to the substrate 404 through the metal bonding layer 408. The metal bonding layer 408 can 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, and serves as a P electrode. In some embodiments, the thickness of the metal bonding layer 408 is about 0.1 microns to 3 microns. In a preferred embodiment, the thickness of the metal bonding layer 408 is about 0.3 μm. 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 on a layer above the metal bonding layer in the LED device 400. The corresponding bonding metal layer is also deposited on the substrate 404. In some embodiments, the components of the metal bonding layer 408 include 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 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 thickness of the two Au layers is approximately the same, under high pressure and high temperature, the Au on the two layers diffuse mutually to bond the two layers together. Eutectic bonding, hot pressing bonding, and transient liquid phase (TLP) bonding are exemplary techniques that can be used.

[0301] In some embodiments, the metal bonding layer 408 may also act as a reflector to reflect light emitted from the LED structure above.

[0302] 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 In the Figure 4B In some embodiments not shown in the figure, 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 can 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 transmittance.

[0303] In some embodiments, the red LED light emitting layer 412 has an extension portion 464 on one side thereof relative to other layers above. In some embodiments, the extension portion 464 extends together with the conductive layers 410 and 414. In some embodiments, the extension portion 464 is connected to the N-electrode contact pad 416 through the extension portion of the conductive layer 414 above the extension portion 464.

[0304] In some embodiments, reflective layer 409 is located between conductive layer 410 and metal bonding layer 408 below red LED light emitting layer 412 , reflective layer 415 is located between conductive layer 414 and bonding layer 456 above red LED light emitting layer 412 , and in one example, is located within planarized insulating layer 454 .

[0305] In one method, the red LED light emitting layer 412 is grown on a separate substrate (called an 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 in .

[0306] In some embodiments, the red LED light emitting layer 412 is used to form a red micro-LED. Examples of red LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the red LED light emitting layer 412 may include a layer of P-type GaP / P-type AlGaInP light emitting layer / AlGaInP / N-type AlGaInP / N-type GaAs. In some embodiments, the P-type layer is typically Mg-doped, and the N-type layer is typically Si-doped. In some examples, the thickness of the red LED light emitting layer is approximately 0.1 microns to 5 microns. In a preferred embodiment, the thickness of the red LED light emitting layer is approximately 0.3 microns.

[0307] 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 in a planarized insulating layer 454, for example, 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 in 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.

[0308] In some embodiments, a planarization layer such as 454 is transparent to light emitted by 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 borophosphosilicate glass (BPSG) or any combination thereof. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive BCL-1200 of Micro Resist, or any combination thereof. In some embodiments, the planarization layer can facilitate the passage of light emitted by micro LED 400. In some embodiments, planarization layers such as 454, 468, and 462 have the same composition as bonding layers such as 456 and 460. In some embodiments, planarization layers such as 454, 468, and 462 have different compositions from bonding layers such as 456 and 460.

[0309] In some embodiments, vias or through-holes are formed in the planarized insulating layer 454 to accommodate P-electrode contact elements 422 and 424 for the green LED structure. The P-electrode contact elements 422 and 424 are connected to the driving circuit 406.

[0310] 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 the 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 can also be used as a reflector to reflect light emitted by the LED structure above.

[0311] In some embodiments, when vertical propagation is used, the bonding layer 456 is transparent to the light emitted by the micro-LED 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 borophosphosilicate glass (BPSG), or any combination of the above. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive BCL-1200 from Micro Resist, or any combination of the above. In some embodiments, a transparent bonding layer can facilitate the light emitted by the layer below the bonding layer to pass through.

[0312] 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 transmittance.

[0313] In some embodiments, 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 the conductive layer 428. In some embodiments, the P-electrode contact pad 426 is also connected to the P-electrode contact elements 422 and 424 in the planarized insulating layer 454 through the portion of the P-electrode contact pad 426 in the bonding layer 456. In some embodiments, the P-electrode contact element 422 is cylindrical in shape. In some embodiments, the P-electrode contact element 424 is in a funnel shape with a narrow top side and a wide bottom side, and the narrow top side matches the width of the component 422, and the funnel shape is used to support the element 422 above it. In some embodiments, a conductive layer 432 for electrode connection is formed on the 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 transmittance. In some embodiments, at Figure 4A and Figure 4B 4, 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 through the N-electrode contact element 418 in the transparent bonding layer 456. In some embodiments, a via or through hole is formed in the bonding layer 456 to accommodate a portion of the N-electrode contact element 418 and the P-electrode contact pad 426.

[0314] In some embodiments, the green LED light emitting layer 430 has an extension portion 466 on one side thereof relative to other layers above. In some embodiments, the extension portion 466 extends together with the conductive layers 428 and 432. In some embodiments, the extension portion 466 is connected to the N-electrode contact pad 420 through the extension portion of the conductive layer 432 above the extension portion 466.

[0315] In some embodiments, the lateral dimensions of the green LED light emitting layer 430 are substantially the same as the lateral dimensions of the red LED light emitting layer 412 , particularly with respect to the effective light emitting area.

[0316] In some embodiments, reflective layer 427 is below green LED light emitting layer 430 , between conductive layer 428 and bonding layer 456 , and reflective layer 433 is above green LED light emitting layer 430 , between conductive layer 432 and bonding layer 460 , and in one example, within planarization insulating layer 458 .

[0317] In one method, the green LED light emitting layer 430 is grown on another separate substrate (called an 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 in .

[0318] In some embodiments, the green LED light emitting layer 430 is used to form a green micro-LED. Examples of green LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the green LED light emitting layer 430 may include 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 microns to 5 microns. In a preferred embodiment, the thickness of the green LED light emitting layer is approximately 0.3 microns.

[0319] 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 in 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 in the planarized insulating layer 458. In some embodiments, both surfaces of the planarized insulating layer 458 are smoothed or planarized by a chemical mechanical polishing method.

[0320] In some embodiments, without including extensions such as 464, 466, the first LED structure, e.g., a red LED structure, and the second LED structure, e.g., a green LED structure, have the same central axis. In some embodiments, without including extensions such as 464, 466, the first LED structure and the second LED structure are aligned along the same central axis.

[0321] 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 can also be used as a reflector to reflect light emitted by the LED structure above.

[0322] In some embodiments, when vertical propagation is used, bonding layer 460 is transparent to light emitted by LED device 400. In some embodiments, bonding layer 460 is made of a dielectric material such as a solid inorganic material or a plastic material, as described above for bonding layer 456. In some embodiments, a transparent bonding layer can facilitate light emitted by layers below the bonding layer to pass through.

[0323] 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 transmittance. Figure 4A shown, but in Figure 4B Not shown in the figure, 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 some P-electrode contact elements (eg, 422 and 424) in the planarized insulating layers 454 and 458 and in the transparent bonding layers 456 and 460. Figure 4A and 4B Those P-electrode contact elements are connected to the driving circuit 406.

[0324] 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 transmittance. Figure 4B As shown, N electrode 440 has N electrode contact pads 442 and 444 electrically connected to blue LED light emitting layer 436 through N electrode 440 and conductive layer 438. In some embodiments, N electrode 440 is also electrically connected to N electrode contact pad 420 of green LED structure. In some embodiments, N electrode 440 is made of a material such as graphene, ITO, AZO or FTO or any combination thereof.

[0325] In some embodiments, the lateral dimensions of the blue LED light emitting layer 436 are substantially the same as the lateral dimensions of the green LED light emitting layer 430 , particularly with respect to the effective light emitting area.

[0326] 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).

[0327] In one method, the blue LED light emitting layer 436 is grown on another separate substrate (called an 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 in .

[0328] In some embodiments, the blue LED light emitting layer 436 is used to form a blue micro-LED. Examples of blue LED light emitting layers include III-V nitrides, III-V arsenides, III-V phosphides, and III-V antimonide epitaxial structures. In some cases, the film within the blue LED light emitting layer 436 may include 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 blue LED light emitting layer is approximately 0.1 microns to 5 microns. In a preferred embodiment, the thickness of the blue LED light emitting layer is approximately 0.3 microns.

[0329] 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.

[0330] In some embodiments, vias or through-holes are formed in the planarized insulating layer 462 and the transparent bonding layer 460 to accommodate the portion of the N-electrode 440 connected to the green LED structure N-electrode contact pad 420 .

[0331] In some embodiments, N-electrode 440 covers the top of planarized insulating layer 462. In some embodiments, N-electrode 440 covers the top of tri-color LED device 400. In some embodiments, N-electrode 440 is connected to the N-electrode of the adjacent tri-color LED device via N-electrode contact pads 442 and 444 (at Figure 4A or not shown in 4B), using it as a common electrode.

[0332] In some embodiments, the lateral dimensions of the blue LED structure are approximately the same as the lateral dimensions of the green LED structure. In some embodiments, without including an extension such as 466, the second LED structure, e.g., the green LED structure, and the third LED structure, e.g., the blue LED structure, have the same central axis. In some embodiments, without including an extension such as 466, the second LED structure and the third LED structure are aligned along the same central axis.

[0333] In some embodiments, each of the conductive layers 410, 414, 428, 432, 434, and 438 has a thickness of about 0.01 micrometers to about 1 micrometer. In some cases, each of the conductive layers 410, 414, 428, 432, 434, and 438 is typically deposited on the respective epitaxial layer by a vapor deposition process, such as electron beam evaporation or sputtering deposition, before any bonding process with the next epitaxial layer is performed. In some examples, the conductive layer is used to maintain good conductivity of the electrode connection, and in some cases, it is also used to improve the optical properties of the LED device, such as reflectivity or transmittance.

[0334] In some embodiments, to improve the luminous efficiency of the three-color LED device 400, optical isolation structures such as 446 and 448 are formed along the sidewalls of the three-color LED device 400. In some embodiments, the optical isolation structures 446 and 448 are made of a dielectric material such as SiO2.

[0335] like Figure 4AAs shown in the top view in FIG. 4 , in some embodiments, the three-color LED device 400 has a circular shape. In some embodiments, optical isolation structures such as 446 and 448 are connected as a whole and form a circular side wall around the three-color LED device 400. In some embodiments, the optical isolation structure forms a reflective cup described in further detail below. In some embodiments, the three stacked LED structures within the three-color LED device 400 are also circular in shape. In some embodiments, the three-color LED device 400 can be in other shapes, such as a rectangle, a square, a triangle, a trapezoid, a polygon. In some embodiments, optical isolation structures such as 446 and 448 are connected as a whole and form a side wall of other shapes such as a rectangle, a square, a triangle, a trapezoid, a polygon, etc. around the three-color LED device 400.

[0336] 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 may refer to a surface that is not perpendicular to the top surface or the bottom surface of the corresponding LED light emitting layer. In some embodiments, the angle between the inclined side wall and the bottom surface of the corresponding LED light emitting layer is less than 90 degrees. In some embodiments, the metal bonding layer 408 also has an inclined side surface. The inclined side surface can facilitate the connection of different connecting elements to each LED light emitting layer, prevent the connection element from being disconnected due to a sudden change in angle, and enhance the overall stability of the device.

[0337] In some embodiments, the light propagation efficiency of the multicolor LED device changes as the angle of the inclined side surface of the LED light emitting layer relative to the normal of the substrate 404 surface changes. In some embodiments, the light propagation efficiency of the multicolor LED device increases as the angle of the inclined side surface of the LED light emitting layer relative to the normal of the substrate 404 surface increases. 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 reflective 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 reflective cup as described below, the luminous efficiency of the multicolor LED device is 2.7%. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the surface of the substrate 404 is at (for example, 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 reflective cup as described below, the luminous efficiency of the multi-color LED device is equal to or very close to 56.4%.

[0338] In contrast, the implementation of the reflective cup structure as described in further detail below improves the light propagation efficiency of the multi-color LED device. 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 a reflective cup as described below, the luminous efficiency of the multi-color LED device is 0.65%, that is, an increase of 104.6% compared to the LED device without the reflective cup. 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 ±15 degrees and when the optical isolation structure such as 446 and / or 448 is a reflective cup as described below, the luminous efficiency of the multi-color LED device is 6.65%, that is, an increase of 144.4% compared to the LED device without the reflective cup. For example, when the angle of the side surface of the LED light emitting layer relative to the normal of the surface of the substrate 404 is at (for example, 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 reflective cup as described below, the luminous efficiency of the multi-color LED device is equal to or very close to 66.65%, that is, an increase of 18.4% compared to the LED device without a reflective cup.

[0339] 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 for the effective light emitting area.

[0340] In some embodiments, a reflective layer is formed above and below each layer of the LED light-emitting layer to improve light transmission efficiency. 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, in the case where the 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 (or / and within the planarized insulating layer 454) and the red LED light emitting layer 412. In some embodiments, in the case where the conductive layer 414 is present, the reflective layer 415 is formed between the bonding layer 456 (or / and within the planarized insulating layer 454) and the conductive layer 414.

[0341] In some embodiments, a reflective layer 427 is formed between the bonding layer 456 (or / and within the planarized insulating layer 458) and the green LED light emitting layer 430. In some embodiments, in the case where the conductive layer 428 is present, the reflective layer 427 is formed between the bonding layer 456 (or / 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 (or / and within the planarized insulating layer 458) and the green LED light emitting layer 430. In some embodiments, in the case where the conductive layer 432 is present, the reflective layer 433 is formed between the bonding layer 460 (or / and within the planarized insulating layer 458) and the conductive layer 432.

[0342] In some embodiments, a reflective layer 435 is formed between the bonding layer 460 (or / and within the planarized insulating layer 462) and the blue LED light emitting layer 436. In some embodiments, in the presence of the conductive layer 434, the reflective layer 435 is formed between the bonding layer 460 (or / and 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 43), while still allowing the blue LED light emitting layer 436 to be electrically connected to the N-electrode pad 440, for example, through a conductive path. In some embodiments, where the conductive layer 438 is present, 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, through a conductive path.

[0343] In some embodiments, the materials, composition, properties, and manufacturing process of the reflective layer are the same as described above with respect to FIGS. 1-3 .

[0344] In some embodiments, a three-color LED structure is formed by dry etching and wet etching, and the axes of the LED structures of different colors are vertically aligned with each other. In some embodiments, the LED structures of different colors share the same axis.

[0345] In some embodiments, each of the plurality of LED structures of different colors is formed in a pyramid shape or a shape with a trapezoidal cross section within its respective planarized insulating structure. Each layer has a narrower width or a smaller area than the layer below it. In this case, the width or area is measured by the size of a plane parallel to the surface of the substrate 404. In some embodiments, especially when a planarized layered structure is used, each LED structure in the LED structures of different colors has substantially the same lateral size compared to the other LED structures. When each LED structure in the LED structure has substantially the same area, the luminous efficiency of the entire LED device is improved.

[0346] In some embodiments, especially when a planarized layered structure is not used, each LED structure in the LED structures of different colors is bonded together by a bonding layer that only covers the LED structure area without extending beyond the LED structure area, and the entire multi-color LED device forms a pyramid (or inverted cone) shape or a trapezoidal cross-section shape (in Figure 4B ). In some embodiments, the lateral dimension of the bottom LED structure, such as the red LED structure, can be the longest, and the lateral dimension of the top LED structure, such as the blue LED structure, can be the shortest. The pyramid shape can be naturally formed from the bottom to the top when the various layers in the LED device are etched and patterned. The pyramid structure can improve the electronic connection between the individual LED structures and between the electrodes and simplify the manufacturing process. For example, the electrode connection elements of each layer are exposed in each layer to facilitate connection.

[0347] In some embodiments, the bottom layer, such as metal bonding layer 408, has a lateral dimension of about 1 micron to 500 microns. In a preferred embodiment, the lateral dimension of metal bonding layer 408 at the bottom of the multi-color LED device is about 2.0 microns. In some embodiments, the vertical height of the multi-color LED device is about 1 micron to 500 microns. In a preferred embodiment, the vertical height of the multi-color LED device is about 1.9 microns. In a preferred embodiment, the lateral dimension of conductive layer 438 at the top of the multi-color LED device is about 1.0 micron.

[0348] In some embodiments, the cross-sectional aspect ratio of the layers in the tri-color LED device remains substantially the same when the lateral dimension of the same layer changes. For example, when the lateral dimension of the patterned epitaxial layer is 5 microns, the thickness of the patterned epitaxial layer is less than one micron. 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 cross-sectional aspect ratio of the epitaxial layer and other layers is less than 1 / 5 of the thickness / width.

[0349] The shape of the LED device is not limited, and in some other embodiments, the cross-sectional shape of the three-color LED device can adopt other shapes, such as an inverted trapezoid, a semi-ellipse, a rectangle, a parallelogram, a triangle or a hexagon, etc.

[0350] In some embodiments, a planarized insulating layer, such as 454, 458, and 462, is used to cover each LED structure of different colors, thereby simplifying the manufacturing process of a single-pixel three-color LED device and improving the luminous efficiency of a single-pixel three-color LED device. For example, each LED structure of different colors can first be independently formed in a corresponding planarized insulating layer to include a conductive layer, a reflective layer, and an electrode contact pad and their related connectors, and then each LED structure is bonded together through a corresponding bonding layer.

[0351] In contrast, in the process of manufacturing a directly stacked three-color LED device without a planarization feature, the LED structures of different colors are directly bonded together using some bonding layers, and a single pixel three-color LED device can be formed into a pyramid (or inverted cone) shape or a trapezoidal shape in cross section due to layer-by-layer patterning (and / or etching). Therefore, the effective light-emitting area for the LED structure at the bottom of the stack of the single pixel three-color LED device is the largest, while the effective light-emitting area for the LED structure at the top of the stack is the smallest. The non-uniformity of the light-emitting area between multiple LED structures in the LED device will reduce its luminous efficiency. Although it has a planarized layered structure, since each LED structure is manufactured in its own planarized insulating layer, the single pixel three-color LED device is not limited to the pyramid structure as described above. On the contrary, the effective light-emitting area of ​​different LED structures in a single pixel three-color LED device can be adjusted according to the design. In some cases, the horizontal effective light-emitting area of ​​different LED structures in a single pixel three-color LED device is substantially the same to improve the luminous efficiency and make it easier to electrically connect. In some cases, the planarized three-color LED structure can increase the luminous efficiency by at least 5%, at least 10%, or sometimes, at least 20%, compared to a similar three-color LED structure without planarization.

[0352] In some embodiments, when a corresponding epitaxial substrate is used to grow each layer of the LED light-emitting layer as described above, an insulating layer may be first deposited on the epitaxial substrate covering the corresponding LED light-emitting layer and each of the other layers such as the conductive layer and the reflective layer. Then, a planarization process is performed to make the surface of the insulating layer in which the corresponding LED structure is embedded flat. Vias for electrical connection are also formed in the planarized layer before bonding.

[0353] In another embodiment, the layers of the LED structure including the bonding layer can be formed directly on the planarized insulating layer with the formed LED structure already embedded therein, and then the planarized insulating layer is formed to cover the current LED structure. Before the next LED structure is formed over the current LED structure, vias for electrical connection are formed in the planarized layer.

[0354] Compared to some other processes where there is no planarized insulating layer and the bonding layer directly contacts the top or bottom of the LED structure to form a device, 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 damaging forces. In addition, the planarized surface can improve light propagation efficiency by reducing deflection caused by uneven surfaces.

[0355] 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 three-color LED device 400, including layers 410, 414, 428, 432, 434, and 438.

[0356] In some embodiments, blue LED light emitting layer 436 and 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 C12 and BC13 etching gases.

[0357] In some embodiments, the bonding layer including 460 and 456 is patterned using photolithography and etching. In some cases, the etching method used to form the patterning is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases.

[0358] In some embodiments, the reflective layer including 409, 415, 427, 433, 435 and 439 is patterned using photolithography and etching. In some cases, the etching method used to pattern the reflective layer, especially the DBR layer, is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2 etching gases or ion beam etching (IBE) using Ar gas.

[0359] 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 C12 and HBr etching gases.

[0360] In some embodiments, metal bonding layer 408 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 C12 / BC13 / Ar etching gas, or ion beam etching (IBE) using Ar gas.

[0361] In some embodiments, after each of the LED device structures is patterned, an insulating layer such as 454, 458, 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 curing a layer such as SOG at high temperature. In some embodiments, the insulating layer is made of a material having a thermal coefficient similar to the thermal coefficient of the layers below the insulating layer. The surface of the insulating layer is then smoothed or planarized by related methods such as chemical mechanical polishing as understood by those of ordinary skill in the art.

[0362] In some embodiments, the insulating layer after planarization is patterned using photolithography and etching to expose the electrode contact area. In some cases, the etching method used to form the patterning is dry etching, for example, inductively coupled plasma (ICP) etching using CF4 and O2.

[0363] In some embodiments, a P-electrode or anode metal pad is deposited at a suitable location of the patterned LED structure, such as on one side and / or in a via within a planarized insulating layer, using vapor deposition or by other deposition methods to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0364] In some embodiments, a separate N-electrode or cathode metal pad is deposited using vapor deposition or by other deposition methods at a suitable location of the patterned LED structure, such as on the side / top and / or in a via within a planarized insulating layer to electrically connect the red LED structure, the green LED structure, and the blue LED structure.

[0365] Figure 5 The single pixel three-color LED device 500 with a refractive structure according to some embodiments is Figure 1A 102. In some embodiments, although not all Figure 51-4, but adds a refractive structure 502 formed above the top surface of the single-pixel three-color LED device to improve the luminous efficiency. The light emitted by the single-pixel three-color LED device is emitted through the top surface of the single-pixel three-color LED device without the refractive structure (light emitting area). 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 the top electrode such as the N electrode 140. In some embodiments, the refractive structure 502 is directly formed on the surface of the planarized insulating layer 176. In some embodiments, the refractive structure 502 is the same as the planarized insulating layer 176 and is integrated with the planarized insulating layer 176.

[0366] In some embodiments, the refractive structure 502 is formed between the optical isolation structure of the reflective cups such as 146 and 148 and the top surface of the single pixel three-color LED device without the refractive structure, i.e., the light emitting area. 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 located above a top electrode such as N-electrode 140. In some embodiments, the top surface of the refractive structure is at the same height as the top electrode such as N-electrode 140 or below the top electrode.

[0367] In some embodiments, the refractive structure 502 changes the optical path of the light emitted by the three-color LED device of a single pixel by making the light emitted by the LED device more focused or more divergent according to design requirements.

[0368] 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 the single pixel three-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.

[0369] In some embodiments, the refractive layer 502 is formed directly on the planarized insulating layer. In some embodiments, the refractive layer 502 is formed by deposition, sputtering or other methods.

[0370] Fig. 6A A single pixel three-color LED device 600 with a microlens on a reflective structure according to some embodiments Figure 1A A cross-sectional view along the diagonal line 102 .

[0371] Figure 6B A single pixel three-color LED device 600 having a microlens within the area formed by the reflective structure according to some embodiments Figure 1A A cross-sectional view along the diagonal line 102 .

[0372] In some embodiments, although not all Figure 6A-6B 1-5, but the single pixel three-color LED device 600 has a structure similar to any of the single pixel three-color LED devices shown in FIGS. 1-5, and a microlens 602 formed above the top surface of the single pixel three-color LED device is added to improve the light emitting efficiency. Without the microlens structure (light emitting area), the light emitted by the single pixel three-color LED device is emitted through the top surface of the single pixel three-color LED device. In some embodiments, the microlens 602 is directly formed on the surface of the planarized insulating layer 176. In some embodiments, the microlens 602 is directly formed on the surface of the planarized insulating layer 176. Figure 5 The microlens 602 is shown on the surface of the refractive structure 502. In some embodiments, the microlens 602 covers and contacts the exposed surface of the top electrode such as the N-electrode 140.

[0373] In some embodiments, optional spacers 604 are formed on top of the light emitting regions at the bottom of microlenses 602. In some embodiments, the top surface of spacers 604 is planarized. In some embodiments, spacers 604 are formed directly on the surface of planarized insulating layer 176. In some embodiments, spacers 604 are formed directly on the surface of planarized insulating layer 176. Figure 5 On the surface of the refractive structure 502 shown. In some embodiments, the spacer 604 is Figure 5 The refractive structure 502 shown is the same as and integrated with the refractive structure 502. 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 the same as and integrated with the planarized insulating layer 176.

[0374] In some embodiments, microlens 602 is formed between each optical isolation structure such as reflective structures 146 and 148 or reflective cups and the top surface of a single pixel three-color LED device that does not have a microlens, i.e., a light emitting area, 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 Fig. 6AWhen the top surface of the microlens 602 is located above the top of the reflective structure such as 146 and 148, the microlens 602 can basically capture and focus all the light emitted by the single pixel three-color LED device including the reflective cup. Figure 6B The top of the optical isolation structure is shown to be 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 the top of the reflective structure such as 146 and 148 or below the top of the reflective structure, at least a portion of the light emitted by the microlens 602 is further reflected by the reflective structure or reflective cup confined within a certain area.

[0375] In some embodiments, the lateral dimension of the bottom of the microlens 602 is smaller than the lateral dimension of the light emitting area. 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 area. In some embodiments, the lateral dimension of the bottom of the microlens 602 is smaller than the lateral dimension of the top surface area 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 area of ​​the top light emitting layer 136.

[0376] In some embodiments, an optional spacer 604 is formed between an optical isolation structure such as a reflective cup 146 and 148 and a top surface of a single pixel three-color LED device without a microlens and a spacer, i.e., a light emitting area. In some embodiments, the top surface of the spacer 604 is located above the top of the optical isolation structure. In some embodiments, the top surface of the spacer 604 is at the same height as or lower than the top of the optical isolation structure. In some embodiments, the top surface of the spacer 604 is located above a top electrode such as an N-electrode 140. In some embodiments, the top surface of the spacer 604 is at the same height as or lower than the top electrode such as an N-electrode 140. In some embodiments, the lateral dimension of the bottom of the microlens 602 is smaller than the lateral dimension of the top surface of the spacer 604. 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 of the spacer 604.

[0377] In some embodiments, the microlens 602 changes the optical path of the light emitted by the single-pixel three-color LED device by making the light emitted by the single-pixel three-color LED device more focused or more divergent according to design requirements.

[0378] In some embodiments, the spacer 604 lengthens the optical path of light emitted by a single pixel tricolor LED device. In some embodiments, the spacer 604 changes the optical path of light emitted by a single pixel tricolor LED device by making the light emitted by the single pixel tricolor LED device more focused or more divergent according to design requirements.

[0379] In some embodiments, the microlens 602 can be made of various materials that are transparent to the wavelengths of light emitted by the single pixel three-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.

[0380] The spacer 604 is an optically transparent layer formed to maintain the position of the microlens 602 relative to the pixel light source such as a single pixel three-color LED device below the microlens 602. The spacer 604 can be made of various materials that are transparent to the wavelengths of light emitted by the pixel light source. For example, exemplary transparent materials for the 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, the spacer 604 is made of photoresist. In some embodiments, the spacer 604 and the microlens 602 have the same material. In some embodiments, the spacer 604 and the microlens 602 have different materials.

[0381] In some embodiments, the height of microlens 602 is no greater than 2 microns. In some embodiments, the height of microlens 602 is no greater than 1 micron. In some embodiments, the height of microlens 602 is no greater than 0.5 microns. In some embodiments, the width of microlens 602 is no greater than 4 microns. In some embodiments, the width of microlens 602 is no greater than 3 microns. In some embodiments, the width of microlens 602 is no greater than 2 microns. In some embodiments, the width of microlens 602 is no greater than 1 micron. In some embodiments, the ratio of width to height of microlens 602 is greater than 2.

[0382] In some embodiments, the shape of the microlens 602 is substantially hemispherical. In some embodiments, the central axis of the microlens 602 is aligned with or identical to the central axis of the single pixel three-color LED device without a lens.

[0383] For the sake of clarity, Figure 6A-6BIt is shown that in some embodiments, in a display panel, each pixel light source in a single pixel light source such as a three-color LED device corresponds to a microlens 602. It should be understood that a complete display panel includes an array of many individual pixels and many microlenses. In addition, there may not be a one-to-one correspondence between the microlenses and the pixel light sources, and there may not be a one-to-one correspondence between the pixel driving circuit (not shown) and the pixel light source. The pixel light source may also be made of multiple individual optical elements, for example, multiple single pixel LEDs connected in parallel. In some embodiments, one microlens 602 may cover multiple single pixel three-color LED devices without lenses.

[0384] 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 light beam emitted by the pixel light source has a relatively wide original divergence angle. In one embodiment, the original angle of the edge light of the light beam relative to the vertical axis perpendicular to the substrate 104 is greater than 60 degrees. The light is bent by the microlens 602 so that the new edge light now has a reduced divergence angle. In one embodiment, the reduced angle is less than 30 degrees. The microlenses in the microlens array are generally identical. Examples of microlenses include spherical microlenses, aspherical microlenses, FRESNAL microlenses, and cylindrical microlenses.

[0385] The microlens 602 typically has a planar side and a curved side. In FIG6 , the bottom of the microlens 602 is the planar side and the top of the microlens 602 is the curved side. Typical shapes of the base of each microlens 602 include circular, square, rectangular, and hexagonal. The individual microlenses in the microlens array of the display panel can be the same or different in shape, curvature, optical power, size, base, spacing, etc. In some embodiments, the microlens 602 conforms to the shape of a single pixel three-color LED device. In one example, the shape of the base of the microlens 602 is the same as the shape of a single pixel three-color LED device, for example, Figure 6A-6B In another example, the shape of the microlens 602 base is different from the shape of the single pixel tri-color LED device, for example, the circular base of the microlens has the same width as the single pixel tri-color LED, but a smaller area because the microlens base is circular and the base of the single pixel tri-color LED is square. In some embodiments, the microlens base area is smaller than the area of ​​the pixel light source. In some embodiments, the microlens base area is the same as or larger than the area of ​​the pixel light source.

[0386] In some embodiments, when forming microlenses 602, spacer layer 604 can be formed by the same process and the same material as microlenses 602. In some embodiments, the height of the pixel light source measured from the bottom of substrate 104 is greater than, equal to, or less than the thickness of spacer 604.

[0387] 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 micron. 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 microns. 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 microns. In some embodiments, the thickness of the spacer 604 measured from the top surface of the pixel light source is approximately 1 micron.

[0388] In some embodiments, a brightness enhancement effect is achieved by integrating a microlens array onto a display panel. In some examples, due to the light-gathering effect of the microlenses, the brightness with the microlens array is 4 times the brightness without the 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 the optical spacer. For example, a factor greater than 8 can be achieved.

[0389] In some embodiments, the first method for manufacturing a microlens includes the steps of directly depositing a microlens material layer on top of at least 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 substantially flat, and the shape of the formed microlens 602 is substantially 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 three-color LED device, by chemical vapor deposition (CVD) technology. In some embodiments, the deposition parameters for the CVD process are: power of about 0W to 1000W, pressure of about 100 mTorr to 2000 mTorr, temperature of about 23°C to 500°C, gas flow of about 0 to 3000 sccm (standard cubic centimeters per minute), and time of about 1 hour to 3 hours. In some embodiments, the material of the microlens material layer is a dielectric material such as silicon dioxide.

[0390] In some embodiments, the first method for manufacturing a microlens further includes the step of patterning the microlens material layer to expose the electrode region of the 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 also includes patterning the mask by 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 also 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 by a wet etching method.

[0391] In some embodiments, the second method for manufacturing a microlens further includes an optional step of forming a marking layer with markings for alignment with a microlens material layer deposited in a subsequent step. For example, the marking layer is formed to align the unit of the light-emitting pixel with the microlens material layer so as to form a microlens in the center of the pixel light source. In some embodiments, the marking layer is formed to align the pixel light source with the layer above it, especially the microlens material layer, so as to form a microlens on top of the pixel light source.

[0392] The second method for manufacturing a microlens further comprises the step of depositing a layer of microlens material directly on top of at least one pixel light source. Figure 6C-6D Further shown are methods for manufacturing a display panel integrated with a microlens array using top-down pattern transfer according to some embodiments. Figure 6C As shown, the 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 on the top of the pixel light source array 606 by spin coating. 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.

[0393] A second method for fabricating microlenses also includes top-down patterning of a microlens material layer such that Figure 6C-6D The step of forming at least one hemisphere in the microlens material layer is shown. 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 disposed above at least one pixel light source 606M.

[0394] In some embodiments, the step of patterning the microlens material layer from top to bottom further includes: Figure 6C The first step of depositing a mask layer 630 on the surface of a microlens material layer 645 is shown in FIG.

[0395] The step of patterning the microlens material layer from top to bottom also 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 separate units 640, such as in Figure 6C As shown in the dotted rectangular unit in the figure, preparation is made for the formation of the hemispherical pattern. As an example, the separated unit 640 is patterned and formed by a photolithography process. The patterned photosensitive polymer mask layer 650 with the separated unit 640 is then formed into a hemispherical pattern 660 by a high temperature reflow process. In one method, the separated unit 640 is formed into a separated hemispherical pattern 660 by high temperature reflow. In some embodiments, the separated hemispherical pattern 660 of one pixel is not in direct physical contact with the hemispherical pattern of the adjacent pixel. In some embodiments, the hemispherical pattern 660 of one pixel is only in contact with the hemispherical pattern of the adjacent pixel 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 time. After the polymer material melts to a liquefied state, the surface tension of the liquefied material causes it to become a shape with a smooth curvature surface. For a cell with a circular base with a radius R, when the height of the cell is 2R / 3, a hemispherical shape / pattern will be formed after the reflow process. Figure 6C A display panel is shown with an array of hemispherical patterns 660 integrated therein after the high temperature reflow process is completed. In some embodiments, the hemispherical pattern 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 pattern in the mask layer can be formed using grayscale mask lithography exposure. In some other embodiments, the hemispherical pattern in the mask layer can be formed via a molding / imprinting process.

[0396] The step of patterning the microlens material layer from top to bottom also includes a third step of etching the microlens material layer 645 using the hemispherical pattern 660 as a mask to form a hemisphere in the microlens material layer 645. In some examples, etching the microlens material layer 645 is performed by a photolithography process. In some examples, etching the microlens material layer 645 is performed by a process such as Figure 6C In some embodiments, after the microlens material layer 645 is etched, the microlens material layer 645 is not etched through to expose the top surface of the pixel light source 606M, such as Figure 6C-6D As shown, the spacer 670 is formed on the top of the pixel light source 606M or covers the top of the pixel light source 606M, as shown in FIG. Fig.6D shown.

[0397] The second method for manufacturing a microlens also includes patterning the microlens material layer to expose the electrode area of ​​the substrate (at Fig.6D 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 also includes the step of patterning the mask by a photolithography process to form an opening in the mask to expose the microlens material layer above the electrode area of ​​the pixel light source. The etching step further includes the step of etching the exposed microlens material layer with mask protection. In some embodiments, the exposed microlens material layer is etched by a wet etching method. In some embodiments, the opening for the electrode is provided outside the display array area.

[0398] As mentioned above, Figures 6A to 6D Various manufacturing methods are shown to form a display panel with an integrated microlens array. It should be understood that these are only examples and other manufacturing techniques may also be used.

[0399] Although the detailed description contains many details, these should not be construed as limiting the scope of the invention, but are merely construed 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.

[0400] Figure 7 is an edge of three single pixel tri-color LED devices 710, 720, and 730 located on substrate 104 according to some embodiments. Figure 1A A cross-sectional view 700 of a diagonal line such as 102. In some embodiments, although not all Figure 7 1 to 6. As shown in FIG. 1, each of the single pixel three-color LED devices 710, 720, and 730 has a similar structure to any of the single pixel three-color LED devices shown in FIG. 1 to 6. The cross-sectional view of the single pixel three-color LED device 710 within rectangle 750 is equivalent to the cross-sectional view shown in any of the figures of FIG. 1 to 6 as described above.

[0401] In some embodiments, as shown in any of the embodiments in FIGS. 1-7 , the single pixel three-color LED device further includes one or more reflective cup structures, such as 702, 704, and 706. The reflective structures, such as 702, 704, and 706, surround the respective single pixel three-color LED devices 710, 720, and 730. The reflective cup can be formed on the semiconductor substrate 104 and is arranged to surround the light emitting area where the light emitted by the single pixel three-color LED is emitted. For example, Figures 1A-1C As shown, according to Figure 1B A cross-sectional view along the direction 102, and according to Figure 1C In the cross-sectional view along the direction 150 in FIG. 1 , the reflector cup may include four reflector cup portions 146, 148, 170, and 172. In some embodiments, the reflector cup portions 146, 148, 170, and 172 may be formed on the semiconductor substrate 104 and positioned around the light emitting area. In some embodiments, the reflector cup may isolate at least some or substantially all of the light emitted from the light emitting area. For example, as shown in FIG. 1B-1C , when the height of the reflector cup is higher than the height of the light emitting area, the reflector cup portions 146, 148, 170, and 172 may isolate at least some or substantially all of the light emitted from the light emitting area. Therefore, the reflector cup may suppress light crosstalk between pixels and improve the overall contrast of the LED display. The reflection in the reflector cup also increases the luminous efficiency and brightness by focusing the light emission in a particular direction.

[0402] In some embodiments, the height of the reflector cup may be greater than the height of the bottom LED structure such as the red LED structure, greater than the height of the middle LED structure such as the green LED structure, or greater than the height of the top LED structure such as the 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 the red LED structure, the middle LED structure such as the green LED structure, and the top LED structure such as the blue LED structure. In some embodiments, the total height of the reflector cup may be greater than the height of a single pixel three-color LED device without planarized layers. In some embodiments, the height of the reflector cup is between 0.5 microns and 50 microns. In some embodiments, the height of the reflector cup is between 1 micron and 20 microns. In some embodiments, the height of the reflector cup is between 2 microns and 10 microns. In a preferred embodiment, the height of the reflector cup is about 2.5 microns, while the height of a single pixel three-color LED device without planarized layers is about 1.9 microns. However, in some embodiments, the 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 reflective cup portion such as 146 or 148 is a trapezoid whose bottom side is longer than the top side. In some embodiments, the bottom width of the reflective cup portion such as 146 or 148 is between 0.3 microns and 50 microns. In some embodiments, the bottom width of the reflective cup portion such as 146 or 148 is between 0.5 microns and 25 microns. In a preferred embodiment, the bottom width of the reflective cup portion such as 146 or 148 is about 1 micron. In some embodiments, the distance from the nearest edge of the bottom of the reflective cup portion such as 146 or 148 to the nearest edge of the bottom of the single-pixel three-color LED device is between 0.2 microns and 30 microns. In some embodiments, the distance from the nearest edge of the bottom of the reflective cup portion such as 146 or 148 to the nearest edge of the bottom of the single-pixel three-color LED device is between 0.4 microns and 10 microns. In a preferred embodiment, the distance from the nearest edge of the bottom of the reflective cup portion such as 146 / 446 or 148 / 448 to the nearest edge of the bottom of the single-pixel three-color LED device is between 10 microns and 15 microns. Figure 4B The distance of the P-electrode connection structure 422 is shown to be approximately 0.6 microns.

[0403] In some embodiments, the distance between the centers of adjacent reflective cup portions such as 146 / 446 and 148 / 448 in a single pixel three-color LED device is between 1 micron and 50 microns. In a preferred embodiment, the distance between the centers of adjacent reflective cup portions such as 146 and 148 in a single pixel three-color LED device is about 5 microns.

[0404] In some embodiments, a divergence angle of 0° may correspond to light propagation perpendicular to the top surface of the light emitting region, and a divergence angle of 90° may correspond to light propagation parallel to the top surface of the light emitting region. Changing the geometry of the reflector cup may control the divergence angle of the light emitted by the light emitting region. Thus, the reflector cup may 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, as Figure 1B-1C The side walls 146-1, 148-1, 170-1 and 172-1 of the reflective cup shown can be straight, curved, wavy, multi-line or a combination thereof. In some embodiments, the steepness of the side walls of the reflective cup portions 146, 148, 170 and 172 can be designed to reduce the divergence of the light emitted by the luminous area. For example, the angle of the side walls of the reflective cup portions 146, 148, 170 and 172 relative to the vertical axis perpendicular to the substrate 104 can be from a minimum of 15 degrees to a maximum of 75 degrees. The angle of the side walls of the reflective cup portions 146, 148, 170 and 172 relative to the vertical axis perpendicular to the substrate 104 can be from a minimum of 5 degrees to a maximum of 60 degrees. In some preferred embodiments, the angle of the side walls of the reflective cup portions 146, 148, 170 and 172 relative to the vertical axis perpendicular to the substrate 104 can be from a minimum of 10 degrees to a maximum of 50 degrees. The reflective cup can also reflect some of the light emitted by the luminous area upward. For example, some of the light emitted by the light emitting area may reach the reflective cup portions 146, 148, 170, and 172 and be reflected upward by them.

[0405] In some embodiments, the reflective cup may include a metal. In some embodiments, the reflective cup may include a dielectric material such as silicon oxide. In some embodiments, the reflective cup 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 reflective cup may include a photoresist.

[0406] In some embodiments, the reflective cup can be manufactured by a combination of deposition, photolithography and etching processes. In some embodiments, the reflective cup can be manufactured by other suitable methods. In one method, PSPI forms a reflective cup shape by a photolithography process. Then, a metal layer including one or more metals such as Pt, Rh, Al, Au and Ag with high reflectivity, a stacked DBR layer including a TiO2 / SiO2 layer, any other layer with total reflection characteristics including a multilayer omnidirectional reflector (ODR), or a combination of the above are formed by vapor deposition on the entire surface of the multicolor LED device including the reflective cup as a reflective layer. Next, the reflective layer is shielded by the photoresist in the reflective cup area, and the reflective layer on another area is etched so that the light-emitting area is exposed.

[0407] In another method, an isolation layer including one or more of SiO2, silicon nitride or SU8, which is thicker than the stacked LED structure, is deposited or spin-coated on the stacked LED structure. Then, using a photoresist as a mask, the isolation layer is etched and the isolation layer is formed into a reflective cup shape. Next, a metal layer including one or more metals such as Pt, Rh, Al, Au and Ag with high reflectivity, a stacked DBR layer including a TiO2 / SiO2 layer, any other layer with total reflection characteristics including a multilayer omnidirectional reflector (ODR), or a combination of the above are formed by vapor deposition on the entire surface of the multicolor LED device including a reflective cup as a reflective layer. Finally, the reflective layer is shielded by the photoresist in the reflective cup area, and the reflective layer on another area is etched so that the light-emitting area is exposed.

[0408] In some embodiments, as shown in FIGS. 2-6 , a single pixel three-color LED device further includes one or more top electrodes (e.g., top electrodes 140 / 440, 442, and 444) integrated with the reflective cup. The one or more top electrodes may be electrically connected to the top electrode (layer) 140 / 440. For example, Figure 4B As shown, electrodes 442 and 444 can be integrated with reflective cups, such as reflective cup portions 446 and 448, respectively. Both top electrodes 442 and 444 can extend toward the light-emitting region and be electrically connected to the top electrode (layer) 140 / 440. By adopting one or more top electrodes, the reflective cup can be used as a common P electrode or N electrode for a single pixel three-color LED device. For example, when the top electrode (layer) 140 / 440 is 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 reflective cup can be used as a common P electrode or a common N electrode for a single pixel three-color LED device.

[0409] In some embodiments, the reflective cup further includes one or more reflective coatings. The one or more reflective coatings may be disposed on one or more side walls of the reflective cup, for example, on side walls 146-1, 148-1, 170-1, and 172-1 of the reflective cup. 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, the green LED structure, and the blue LED structure. The one or more reflective coatings may reflect the light emitted by the light-emitting area, thereby improving the brightness and luminous efficacy of the micro LED panel or display. For example, the light emitted by the light-emitting area may reach the one or more reflective coatings and may be reflected upward by them.

[0410] The one or more reflective coatings together with the reflective cup can utilize the reflection direction and / or reflection intensity of the light emitted by the light emitting area. For example, the side walls 146-1, 148-1, 170-1 and 172-1 of the reflective cup are inclined at a certain angle, so the one or more reflective coatings arranged on the side walls 146-1, 148-1, 170-1 and 172-1 of the reflective cup are inclined at the same angle as the side walls 146-1, 148-1, 170-1 and 172-1 of the reflective cup. When the light emitted by the light emitting area reaches the one or more reflective coatings, the light emitted by the light emitting area is reflected by the one or more reflective coatings according to the angles of the side walls 146-1, 148-1, 170-1 and 172-1 of the reflective cup.

[0411] The material of the one or more reflective coatings may be highly reflective, having a reflectivity greater than 60%, 70% or 80%, and thus may reflect most of the light emitted by the light emitting area. 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 some other embodiments, the one or more reflective coatings may be multilayered. More specifically, the one or more reflective coatings may include one or more layers of reflective materials and one or more layers of dielectric materials stacked. For example, the one or more reflective coatings may include a layer of reflective material and a layer of dielectric material. In other embodiments, the one or more reflective coatings may include two layers of reflective materials and a layer of dielectric material located between the two layers of reflective materials. However, in some other embodiments, the one or more reflective coatings may include two layers of dielectric materials and a layer of reflective material located between the two layers of dielectric materials. In some embodiments, the multilayer structure may include two or more metal layers, and the metal layers may include one or more of TiAu, CrAl or TiWAg.

[0412] In some embodiments, the one or more reflective coatings may be a multilayer omnidirectional reflector (ODR) 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.

[0413] In some embodiments, the one or more reflective coatings may be conductive, and then the one or more reflective coatings may also perform the function of electrically contacting a single pixel multicolor LED device. For example, the top electrode (layer) 140 may be electrically connected to the one or more reflective coatings. For 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 so as not to block the light emitted by the light emitting area. Then, the one or more reflective coatings may also be used as a common electrode of an LED structure within a single pixel multicolor LED device and / or a common electrode of an LED on a display panel.

[0414] In some embodiments, a top conductive layer for connecting with the electrode is formed on the top of the multi-color LED device, and the top conductive layer is electrically connected to the reflective cup. In some embodiments, the top conductive layer is in direct contact with the top of the reflective cup or the bottom of the reflective cup.

[0415] In some embodiments, a bottom dielectric layer is formed between the bottom of the reflective cup and the semiconductor substrate.

[0416] In some embodiments, the one or more reflective coatings may be fabricated by one or more of electron beam deposition or sputtering processes.

[0417] In some embodiments, the reflective cup may have a stepped structure. Figure 8 The single pixel three-color LED device 800 with a stepped reflector according to some embodiments is Figure 4AA cross-sectional view of a diagonal line such as 402. In some embodiments, although not all Figure 8 As shown in FIG. 1 , the single pixel three-color LED device 800 has a structure similar to any of the single pixel three-color LED devices having reflective cup portions such as 146, 148, 170, and 172 shown in FIGS. 1-7 , and has a stepped reflective cup. The stepped reflective cup can be formed on the semiconductor substrate 104 / 404 and positioned around the light emitting area. For example, Figure 8 As shown, according to Figure 4A In the cross-sectional view along the diagonal line such as 402, 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, Figure 8 As shown, when the height of the stepped reflector is higher than the height of the light emitting area, the stepped reflector 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 can suppress light crosstalk between pixels and improve the overall contrast of the LED display.

[0418] In some embodiments, the stepped reflector 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 can be the same as the height of the LED structure on the same vertical level. For example, the stepped structures 846-1 and 848-1 each have the same height as the bottom LED structure. The stepped structures 846-2 and 848-2 each have the same height as the middle LED structure. The stepped structures 846-3 and 848-3 each have the same height as the top LED structure. However, in some embodiments, the stepped reflector portions 846 and 848 can have the same or different heights. The stepped reflector can also reflect the light emitted by the light emitting area upward. For example, according to the design, some of the light emitted by the light emitting area can reach the stepped reflector portions 846 and 848 and reflect upward with different patterns for each LED structure in a single pixel multicolor LED device through them. For example, each step can adjust the focus of the emitted (especially horizontal) light in a different pattern. For example, the red light of the light beam from the LED device is focused more in the center and the blue light is focused more at the edge. Therefore, it can reduce the divergence of the light emitted by the light emitting area and enhance the brightness of a single pixel multi-color LED device.

[0419] In some embodiments, the stepped reflector structure may include or form a cavity surrounding the light emitting region. The cavity may include an area surrounded by the stepped reflector and above the semiconductor substrate 404. The cavity may include an inner sidewall, which may include a plurality of inclined surfaces. For example, Figure 8 As shown, the stepped reflector may include or surround a cavity, which may include an area between the stepped reflector portions 846 and 848 and above the semiconductor substrate 404. The light emitting area may be positioned in the cavity and surrounded by the stepped reflector portions 846 and 848.

[0420] 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 the stepped reflector (e.g., stepped reflector 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 angles of the plurality of inclined surfaces (relative to the surface of the substrate 404) increase from the bottom to the top of the cavity. For example, as Figure 8 As shown, the angles of the inclined surfaces 846-1S, 846-2S, and 846-3S are respectively expressed as inclination angles α, β, and γ. The inclination angles of the inclined surfaces 846-1S, 846-2S, and 846-3S may be the same as the inclination angles of the inclined surfaces 848-1S, 848-2S, and 848-3S, respectively. In some embodiments, the inclination angles α, β, and γ remain the same or increase from the bottom to the top of the cavity. In some preferred embodiments, the inclination angles α, β, and γ may gradually decrease from the bottom to the top of the cavity, so that the light emitted by the LED device may be more divergent toward the upper part of the LED device. However, in some embodiments, the inclination angles α, β, and γ may be any angle according to the design. In some embodiments, the cavity may be filled with a silicon-containing material, such as silicon oxide, which may improve optical refraction, increase transmittance, and / or enhance UV resistance and heat resistance. In some embodiments, the cavity may be empty or vacuum. In some embodiments, the inclined surfaces (eg, inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S, and 848-3S) may be straight, curved, wavy, multi-linear, or a combination thereof.

[0421] In some embodiments, the cavity may include a plurality of sub-cavities. The sub-cavities may be formed or surrounded by various inclined surfaces and may have different sizes in the horizontal direction. For example, there may be Figure 8The three sub-cavities shown. The sub-cavity at the bottom of the cavity may include an area 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 sub-cavity in the middle of the cavity may include an area 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 sub-cavity at the top of the cavity may include an area 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 open top 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 Figure 8 As shown, each sub-cavity can be formed or surrounded by a plurality of inclined surfaces 846-1S, 846-2S, 846-3S, 848-1S, 848-2S and 848-3S and have different sizes 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.

[0422] In some embodiments, the heights of the subcavities may be different. For example, the height of the subcavity located in the middle of the cavity may be less than the heights of the other subcavities. The height of the subcavity located at the top of the cavity may be greater than the height of the subcavity located at the bottom of the cavity. In some embodiments, each color LED structure is located in a different subcavity in the subcavity. For example, the bottom red LED structure is located in the subcavity at the bottom of the cavity, and the top blue LED structure is located in the subcavity at the top of the cavity. The middle green LED structure is located in the subcavity in the middle of the cavity. In some embodiments, the subcavity may be filled with silicon-containing materials, such as silicon oxide, which may improve optical refraction, increase light transmittance, and / or enhance ultraviolet aging resistance and heat aging resistance. In some embodiments, the materials of the subcavities may be different. For example, the subcavity at the top of the cavity may be filled with silicon oxide, and the subcavity at the bottom of the cavity may be filled with epoxymethyl silicon. In some embodiments, the subcavity may be empty or vacuum.

[0423] 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 a photoresist. In some embodiments, the manufacturing process of the stepped reflector is similar to that described above with reference to the reflector.

[0424] 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 the stepped reflective cup, 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, the green LED structure, and the blue LED structure. The one or more reflective coatings may reflect the light emitted by the light emitting area, thereby enhancing the brightness and luminous efficacy of the micro LED panel or display. For example, the light emitted by the light emitting area may reach the one or more reflective coatings and may be reflected upward by them.

[0425] The one or more reflective coatings together with the stepped reflective cup can utilize the reflection direction and / or reflection intensity of the light emitted by the light emitting area. For example, the tilt angles α, β, and γ corresponding to the tilted surfaces 846-1S, 846-2S, and 846-3S can become smaller and smaller from the bottom to the top of the cavity, so 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 the light emitted from the light emitting area reaches the one or more reflective coatings, the light emitted from the light emitting area will be reflected by the one or more reflective coatings at the tilt angles α, β, and γ. The tilt angles α, β, and γ can become larger, the same, or smaller, or the tilt angles α, β, and γ can be selected separately according to a specific design.

[0426] The material of the one or more reflective coatings may be highly reflective, having a reflectivity greater than 60%, 70%, or 80%, and may reflect most of the light emitted from the light emitting area. In some embodiments, the material of the one or more reflective coatings is similar to that described above with reference to the reflective cup. In some embodiments, the material 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 the inclined surface 846-1S may be different from the material of the reflective coating disposed on the inclined surfaces 846-2S and 846-3S, respectively.

[0427] In some embodiments, one or more of the reflective coatings can be manufactured by one or more of electron beam deposition or sputtering processes. In some embodiments, each of the one or more step 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, step structures such as 846-1 and 848-1 are formed in the same step before or after the planarized layer 454 is formed. Step structures such as 846-2 and 848-2 are formed in the same step before or after the planarized layer 458 is formed. Step structures such as 846-3 and 848-3 are formed in the same step before or after the planarized layer 462 is formed. In some embodiments, particularly when layer-by-layer planarization is involved in the process of forming a single pixel three-color LED device, the step structure is formed as a result of layer-by-layer processing and bonding misalignment of different planarized layers including the LED structure. In some embodiments, there may be gaps (in the region of 846-1, 846-2, and 846-3) between different step structures, such as 846-1, 846-2, and 846-3, as a result of layer-by-layer processing and misalignment of layer bonding including different planarizations of the LED structure. Figure 8 not shown).

[0428] In some embodiments, the reflective cup may have a floating structure. Fig. 9 The single pixel three-color LED device 900 with a floating reflector according to some embodiments Figure 4A A cross-sectional view of a diagonal line such as 402. In some embodiments, although not all Fig. 9 As shown in , a single pixel three-color LED device 900 has a structure similar to any of the single pixel three-color LED devices shown in FIGS. 1-8 , and has floating reflective cup portions such as 946 and 948 .

[0429] 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. Fig. 9 As shown, the reflective cup portions 946 and 948 surround the light emitting region, and the bottoms of the reflective cup portions 946 and 948 do not directly contact the semiconductor substrate 104, for example, there is a gap between the bottom of the reflective cup and the substrate 104 / 404. In some embodiments, the gap is filled by a planarized insulating layer 454. In some embodiments, light emitted from the light emitting region can reach the reflective cup and be reflected upward by the reflective cup. For example, Fig. 9 As shown, the light emitted from the light emitting area, including the light emitted from the sidewall and / or top of the LED structure, can reach the reflective cups 946 and 948 and be reflected upward by them. Therefore, it can reduce the divergence of the light emitted from the light emitting area and enhance the brightness of the single pixel multi-color LED device.

[0430] 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 multi-color LED device and the display panel. When the production of the single pixel multi-color LED device 900 is completed, the distance is fixed and cannot be adjusted. 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 multi-color 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 or smaller than the distance between the top surface of the bonding layer 408 at the bottom of the light emitting layer 412 to 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 to the top surface of the substrate 404. By adjusting the gap of the floating reflector cup, specific light from certain portions of the single-pixel multicolor LED device 900 may not be reflected or isolated, which may make the light more focused at the selected portion of the device 900 .

[0431] In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 0.5 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 1 micron. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 2 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 5 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 10 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 20 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 50 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 75 microns. In some embodiments, the distance between the bottom of the reflective cup and the top surface of the semiconductor substrate 404 may be less than 100 microns. In general, the distance between the bottom of the reflective 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 reflective cup and the top surface of the semiconductor substrate 404 is no greater than 20 micrometers.

[0432] In some embodiments, the reflective cup can isolate at least some of the light emitted by the light emitting area. Fig. 9 As shown, when the height of the reflector is higher than the height of the light emitting area, the reflector portions 946 and 948 can isolate at least some of the light emitted by the light emitting area. Therefore, the reflector can suppress light crosstalk between pixels and improve the overall contrast of the LED display. The floating reflector has the same or similar components, shape and manufacturing process as the reflector described above (except for the position and orientation).

[0433] FIGS. 1-9 only illustrate a single pixel multicolor LED device according to some embodiments. In other embodiments, the reflective cup may be a different shape when viewed from a top view or a side view. That is, the side wall of the reflective cup surrounding the light emitting area may be circular, triangular, square, rectangular, pentagonal, hexagonal, and octagonal. The side wall of the reflective cup may surround one light emitting area or one single pixel multicolor LED device, or may surround a group of light emitting areas or a group of single pixel multicolor LED devices. For example, the side wall of the reflective cup may surround two or more light emitting areas arranged in the same plane or two or more single pixel multicolor LED devices arranged in the same plane.

[0434] An array of single-pixel multi-color LED devices can be utilized, each of which can include a reflective cup. Each reflective cup can have a different shape when viewed from a top view or a plan view. For example, the reflective cup of the first single-pixel multi-color LED device can be round, and the reflective cup of an adjacent single-pixel multi-color LED device can be square. In addition, the reflective cups can be electrically isolated from each other. The reflective cups can also be isolated if a buffer space is provided between adjacent reflective cups or if the material of the reflective cups may not extend all the way to the interface with adjacent reflective cups. Alternatively, the reflective coating formed on the sidewalls of the reflective cups can simply extend to cover the gap area between adjacent reflective cups. In another embodiment, the reflective cups can be electrically connected to each other via a common electrode such as a top electrode.

[0435] It will be apparent to those skilled in the art that various other modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus of the present invention disclosed herein without departing from the spirit and scope of the present invention as defined in the appended claims. Therefore, the scope of the present invention shall be determined by the appended claims and their legal equivalents.

[0436] Additional embodiments also include various subsets of the above-described embodiments shown in FIGS. 1-9 combined or otherwise rearranged in various other embodiments.

[0437] Various design aspects of a single pixel multicolor LED device, such as the dimensions of the layers (e.g., the width, length, height, and cross-sectional area of ​​each layer), the dimensions of each electrode, the size, shape, spacing, and arrangement of the two or more LED structure layers, bonding layers, reflective layers, and conductive layers, and 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 that vary based on the above design aspects include, for example, size, material, cost, manufacturing efficiency, luminous efficiency, power consumption, directionality, luminous intensity, luminous flux, color, spectrum, and spatial radiation pattern.

[0438] Fig. 10A is a circuit diagram of a matrix of single pixel three-color LED devices 1000 according to some embodiments. Fig. 10A The circuit in includes three pixel drivers 1002 , 1004 and 1006 and three three-color LED devices 1008 , 1010 and 1012 .

[0439] In some embodiments, the display panel includes a plurality of 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. The micro-LED typically has 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.

[0440] In some embodiments, a pixel driver such as 1002 includes a plurality of transistors and capacitors ( Fig. 10A The transistor includes a driving transistor connected to a power supply and a control transistor configured to have a gate connected to a scan signal bus. The capacitor includes a storage capacitor for maintaining a gate voltage of the driving transistor during a period when the scan signal sets other pixels.

[0441] In this example, each of the three tricolor LED devices, such as 1008, has its own integrated circuit (IC) pixel driver 1002. The tricolor LED device 1008 for a single pixel can be viewed 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 tricolor LED device 1008 are connected to the same IC pixel driver 1002 through a common P electrode pad or anode.

[0442] In some embodiments, each red LED, green LED, and blue LED within the same three-color LED device 1008 is connected to a separate N-electrode pad or cathode.

[0443] In some embodiments, all red LEDs, such as 1018, 1024, and 1030, from different three-color LED devices are connected to the same common N electrode 1036. All green LEDs, such as 1016, 1022, and 1028, from different three-color LED devices are connected to the same common N electrode 1034. All blue LEDs, such as 1014, 1020, and 1026, from different three-color LED devices 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 electrode.

[0444] In some embodiments, the connections of the P and N electrodes can be switched and interchanged ( Fig. 10A 1018, 1024, and 1030). For example, the red LED 1018, green LED 1016, and blue LED 1014 within the same three-color LED device 1008 are connected to a shared N electrode pad or cathode. The red LEDs, green LEDs, and blue LEDs within the same three-color LED device 1008 are connected to separate P electrode pads or anodes. All red LEDs from different three-color LED devices, such as 1018, 1024, and 1030, are connected to the same common N electrode 1036.

[0445] Fig. 10B is a circuit diagram of a matrix of single pixel three-color LED devices 1000 according to some embodiments. Fig. 10B Similar to Fig. 10A , except 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, the red LED 1018, the green LED 1016, and the blue LED 1014 are connected to different IC pixel drivers 1002-1, 1002-2, and 1002-3, respectively, within the same tri-color LED device 1008 via separate P-electrode pads or anodes. As can be observed from Figures 1-9, this type of P-electrode connection is shown in some embodiments.

[0446] In addition, in Fig. 10B In some of the embodiments shown, all LEDs of different colors from different three-color LED devices are connected to the same common N electrode 1032 .

[0447] In some embodiments, the connections of the P and N electrodes can be switched and interchanged ( Fig. 10BFor example, the red LED 1018, the green LED 1016, and the blue LED 1014 in the same three-color LED device 1008 are connected to different N electrode pads or cathodes. All LEDs of different colors of different three-color LED devices are connected to the same common P electrode 1032.

[0448] Fig.11 1 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 that defines an 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 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; a shift register or other type of buffer and memory to store and transmit data; a digital-to-analog converter and a level converter; and a scan controller including a clock circuit.

[0449] Pixel region 1150 includes a pixel array. The pixels include micro-LEDs such as multi-color LEDs 1134 integrated with, for example, a pixel driver as described above. In some embodiments, the top of the multi-color LED array is covered with an array of micro-lenses ( Fig.11 In some embodiments, a reflective structure or a reflective cup ( Fig.11 In this example, the display panel 1100 is a color RGB display panel. It includes red, green and blue pixels. In 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), in contact with ground through a ground pad 1136, and also in contact with a control signal. Although in Fig.11 Not shown in the figure, the P electrode of the tricolor LED 1134 and the output of the driving transistor are located inside the LED 1134. The LED current drive signal connection (between the P electrode of the LED and the output of the pixel driver), the ground connection (between the n electrode and the system ground), the power supply voltage Vdd connection (between the source of the pixel driver and the system Vdd), and the control signal connection to the pixel driver gate are made according to various embodiments.

[0450] Fig.11 The drawings are representative only. Other designs will be apparent. For example, the colors do not have to be red, green, and blue. Nor do they have to be arranged in rows or strips. As an example, Fig.11In addition to the square matrix arrangement of pixels shown in , a hexagonal matrix arrangement of pixels may also be used to form the display panel 1100 .

[0451] In some applications, a fully programmable rectangular pixel array is not necessary. Other designs of display panels and displays with a variety of shapes can also be formed using the device structures described herein. One class of examples is special applications, including signage and automobiles. For example, 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 LEDs on and off. Another professional example is automotive headlights and smart 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 by individual pixel drivers.

[0452] Even the lateral arrangement of the devices within each pixel can vary. In Figures 1-9, the LEDs and pixel drivers are arranged vertically, i.e., each LED is located on top of the corresponding pixel driver circuit. Other arrangements are also possible. For example, the pixel driver circuit can also be located "behind", "in front of" or "beside" the LED.

[0453] Different types of display panels can be manufactured. For example, the resolution of display panels can typically range from 8×8 to 3840x2160. Common display resolutions include QVGA with a resolution of 320x240 and an aspect ratio of 4:3, XGA with a resolution of 1024x768 and an aspect ratio of 4:3, D with a resolution of 1280x720 and an aspect ratio of 16:9, FHD with a resolution of 1920×1080 and an aspect ratio of 16:9, UHD with a resolution of 3840x2160 and an aspect ratio of 16:9, and 4K with a resolution of 4096×2160. There can also be a wide variety of pixel sizes, ranging from sub-micron and below to 10mm and above. The size of the overall display area can also vary widely, ranging from as small as a few tens of microns or less on the diagonal to hundreds of inches or more.

[0454] Different applications will also have different requirements for optical brightness and viewing angle. Example applications include direct-view displays, light engines for home / office projectors and portable electronics such as smartphones, laptops, wearable electronics, AR and VR glasses, and retinal projection. Power consumption can range from as low as a few milliwatts for retinal projectors to as high as kilowatts for large-screen outdoor displays, projectors, and smart car headlights. In terms of frame rate, due to the fast response of inorganic LEDs (nanoseconds), the frame rate can be as high as KHz, or even MHz for small resolutions.

[0455] Additional embodiments also include various subsets of the embodiments in Figures 1-11 combined and otherwise rearranged in various other embodiments, for example, with and without a reflective layer, with and without a planarization layer, with and without a reflective cup structure including various shapes and positioning types, with and without a refractive layer, with and without a microlens, with and without a spacer, and with and without a multi-color LED pixel device / unit with and without different electrode connection structures.

[0456] Although the specific description contains many details, these should not be construed as limiting the scope of the invention, but merely 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 above method can be applied to the integration of non-LED and OLED functional devices with non-pixel driver control circuits. Examples of non-LED devices include vertical cavity surface emitting lasers (VCSELs), photodetectors, micro-electromechanical systems (MEMS), silicon photonic devices, power electronic devices, and distributed feedback lasers (DFBs). Examples of other control circuits include current drivers, voltage drivers, transimpedance amplifiers, and logic circuits.

[0457] The foregoing description of the disclosed embodiments is provided to enable making or using the embodiments described herein and variations thereof. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Therefore, the present disclosure is not intended to be limited to the embodiments shown herein, but will conform to the widest scope consistent with the following claims and the principles and novel features disclosed herein.

[0458] Features of the present invention can be implemented by using a computer program product or with the help of a computer program product, such as a storage medium (multiple media) or a computer-readable storage medium (multiple media), wherein or thereon instructions are stored, and these instructions can be used to program a processing system to perform any features presented herein. Storage media can include, but are not limited to, high-speed random access memory, such as DRAM, SRAM, DDRRAM or other random access solid-state memory devices, and can include non-volatile memory, such as one or more magnetic disk storage devices, optical disk storage devices, flash memory devices or other non-volatile solid-state storage devices. Memory optionally includes one or more storage devices located away from the CPU. Memory or optionally non-volatile memory devices in memory include non-temporary computer-readable storage media.

[0459] Features of the present invention stored on any machine-readable medium(s) may be embodied in software and / or firmware for controlling the hardware of a processing system and for enabling the processing system to interact with other mechanisms utilizing the results of the present invention. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0460] It should be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

[0461] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the claims. As used in the description of the embodiments and the appended claims, the singular forms "one", "an" and "the" are intended to also include multiple forms 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 related listed items. It should also be understood that the terms "including" and / or "comprising" when used in this specification specify the presence of said features, integers, steps, operations, elements and / or parts, but do not prevent the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups.

[0462] As used herein, the term "if" may be interpreted to mean "under the circumstances," "when," or "in response to detecting," the stated antecedent is true, depending on the context. Similarly, the phrase "if it is determined that [that stated antecedent is true]" or "if [the stated antecedent is true]" or "when [the stated antecedent is true]" may be interpreted to mean "upon determination" or "in response to determination" or "upon determination" or "upon detection" or "in response to detection," the stated antecedent is true, depending on the context.

[0463] The foregoing description for purposes of illustration has been described with reference to specific embodiments. However, the above illustrative discussion is not intended to be exhaustive or to limit the claims to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments are chosen and described in order to best explain the principles of practical application and operation to enable others skilled in the art to realize.

Claims

1. A micro LED pixel unit, comprising: Semiconductor substrates; A light emitting region formed on the semiconductor substrate includes a plurality of color LED structures, wherein the bottom of each of the plurality of color LED structures is 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 surrounds the light emitting area, wherein the bottom of the floating reflector cup is located above the semiconductor substrate, and light emitted along the horizontal direction 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.

2. The micro LED pixel unit according to claim 1, wherein: The bottom of the floating reflective cup is higher than the top surface of the corresponding bonding metal layer at the bottom of one of the plurality of color LED structures.

3. The micro LED pixel unit according to claim 1, wherein: The floating reflective cup is stepped. 4 . The micro LED pixel unit according to claim 3 , further comprising a micro lens formed above the light emitting area.

5. The micro LED pixel unit according to claim 4, wherein: The top of the floating reflective cup is higher than the top of the microlens. 6 . The micro LED pixel unit according to claim 4 , further comprising a refractive structure located at the bottom of the micro lens, wherein the refractive structure is formed between the floating reflective cup and the light emitting area.

7. The micro LED pixel unit according to claim 4, wherein: The lateral size of the microlens is not less than the lateral size of the light emitting area.

8. The micro LED pixel unit according to claim 4, wherein: The floating reflective cup has a top opening area, and a lateral dimension of the microlens is smaller than a lateral dimension of the top opening area. 9 . The micro LED pixel unit according to claim 3 , further comprising a bottom dielectric layer formed between the floating reflective cup and the semiconductor substrate.

10. The micro LED pixel unit according to claim 1, wherein: The top electrode layer directly contacts the top of the floating reflector or the bottom of the floating reflector.

11. The micro LED pixel unit according to claim 10, wherein: Each of the plurality of colored LED structures comprises a bottom conductive contact layer and a top conductive contact layer, the light emitting layer being 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 through the reflective structure and the corresponding bonding metal layer by means of contact vias, and A top surface of the top conductive contact layer of the top color LED structure contacts the top electrode layer, and an edge of the top conductive contact layer of the color LED structure below the top color LED structure contacts the top electrode layer.

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

13. The micro LED pixel unit according to claim 3, wherein: The stepped floating reflective cup forms a cavity surrounding the light emitting area.

14. The micro LED pixel unit according to claim 13, wherein: The inner side wall of the cavity includes a plurality of inclined surfaces.

15. The micro LED pixel unit according to claim 14, wherein: Angles of the plurality of inclined surfaces relative to the surface of the semiconductor substrate become smaller from the bottom of the cavity to the top of the cavity.

16. The micro LED pixel unit according to claim 14, wherein: The subcavities formed by the plurality of inclined surfaces have different sizes in a horizontal direction.

17. The micro LED pixel unit according to claim 16, wherein: The inner side walls of the sub-cavities are not positioned in the same plane.

18. The micro LED pixel unit according to claim 17, wherein: The heights of the sub-cavities are different.

19. The micro LED pixel unit according to claim 16, wherein: The height of the sub-cavity located in the middle of the cavity is smaller than the heights of the other sub-cavities.

20. The micro LED pixel unit according to claim 16, 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.

21. The micro LED pixel unit according to claim 13, wherein: The plurality of color LED structures also includes a top color LED structure.

22. The micro LED pixel unit according to claim 21, wherein: The top of the cavity is higher than the top of the top color LED structure.

23. The micro LED pixel unit according to claim 13, wherein: The cavity includes a plurality of sub-cavities, and each of the plurality of color LED structures is located in a different sub-cavity of the plurality of sub-cavities.

24. The micro LED pixel unit according to claim 1, wherein: The floating reflective cup is made of metal.

25. The micro LED pixel unit according to claim 1, wherein: Each of the plurality of color LED structures comprises a corresponding extension portion extending from one side of the corresponding 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 through a corresponding second contact via.

26. The micro LED pixel unit according to claim 1, wherein: The plurality of colored LED structures have a same central axis.

27. The micro LED pixel unit according to claim 1, wherein: The reflective structure includes a reflective layer formed at a bottom of each of the plurality of color LED structures, respectively.

28. The micro LED pixel unit according to claim 27, wherein: The thickness of the reflective layer is in the range of 5 nm to 10 nm, and the thickness of each of the plurality of color LED structures does not exceed 300 nm.

29. 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).

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