CN121286129A

CN121286129A - Multicolor miniature LED pixel array

Info

Publication number: CN121286129A
Application number: CN202580002678.XA
Authority: CN
Inventors: 徐群超; 陈伟新
Original assignee: Shanghai Xianyao Display Technology Co ltd
Current assignee: Shanghai Xianyao Display Technology Co ltd
Priority date: 2024-11-13
Filing date: 2025-05-23
Publication date: 2026-01-06

Abstract

A multicolor micro LED unit is described comprising a plurality of multicolor micro LED pixels, each multicolor micro LED pixel comprising a first LED structure emitting a first color light, wherein the first LED structure is formed on a substrate, a first metal pillar formed on the substrate, a second LED structure emitting a second color light, wherein the second LED structure is located on the first metal pillar, and a conductive structure surrounding the plurality of multicolor micro LED pixels.

Description

Multicolor miniature LED pixel array

Technical Field

The present disclosure relates generally to Light Emitting Diode (LED) display devices, and more particularly to multicolor micro LED pixel arrays.

Background

Light Emitting Diodes (LEDs) are widely used in the fields of lighting, backlighting, and displays. Advantages of using LEDs as pixels include high brightness, low operating voltage, low power consumption, large size, long life, impact resistance, and stable performance. With the recent development of mini-LEDs and micro-LED technology, consumer devices and applications such as Augmented Reality (AR), virtual Reality (VR), projection, head-up display (HUD), mobile device display, wearable device display, and in-vehicle display require LED panels with improved resolution and brightness. For example, an AR display integrated within goggles and positioned close to the wearer's eye may have dimensions such as nail size while still requiring HD definition (1280 x 720 pixels) or higher. Many electronic devices require LED panels to have a specific pixel size, distance between adjacent pixels, brightness, and viewing angle. In general, while trying to achieve maximum resolution and brightness on a small display, maintaining both resolution and brightness requirements is challenging. In contrast, in some cases, it is difficult to balance the pixel size and brightness at the same time because they have approximately opposite relationships. For example, obtaining a high luminance per pixel results in a low resolution. Also, obtaining high resolution may reduce brightness.

The light emitted by the LED chip is generated by spontaneous emission and is therefore non-directional, resulting in a large divergence angle. In micro LED displays, a large divergence angle causes various problems. On the one hand, only a small portion of the light emitted by the micro LED can be utilized due to the large divergence angle. This may significantly reduce the efficiency and brightness of the micro LED display system. In addition, due to the large divergence angle, light emitted from one micro LED pixel may strike an adjacent pixel, resulting in optical crosstalk between pixels, loss of sharpness, and loss of contrast. Fig. 1 shows a conventional solution for reducing a large divergence angle in order to reduce light waste to reduce power consumption and light interference between pixels. As shown in fig. 1, an optical isolation structure 110 is located around each micro LED pixel. However, these separate optical isolation structures occupy a large chip area, increase process difficulty, and are detrimental to miniaturization of the micro LED pixel cells.

The multicolor LED designs of the prior art generally employ a coaxial stack structure, i.e. LED chips of different colors are stacked together. In this structure, light emitted from the lower LED light emitting region may pass through the upper LED light emitting region and be emitted from the top outward, or may be emitted from the top outward through a side reflecting structure after traveling laterally. In such coaxially stacked multi-color LED structures, the light propagation path from the underlying LED light emitting region is longer, which increases the probability of light being reflected and absorbed by the optical isolation and electrical connection structures, resulting in higher optical losses. This may significantly reduce the efficiency and brightness of the micro LED display system.

Accordingly, there is a need to provide an LED structure for a display panel that addresses the above-described shortcomings and others.

Disclosure of Invention

There is a need for improved multicolor LED designs to ameliorate and solve the shortcomings of conventional display systems. In particular, there is a need for an LED device structure that can improve brightness and resolution while effectively maintaining low power consumption.

Some example embodiments provide a multicolor micro LED unit including a plurality of multicolor micro LED pixels, each multicolor micro LED pixel including a first LED structure emitting a first color light, wherein the first LED structure is formed on a substrate, a first metal pillar formed on the substrate, a second LED structure emitting a second color light, wherein the second LED structure is located on the first metal pillar, and a conductive structure surrounding the plurality of multicolor micro LED pixels.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, each multicolor micro LED pixel further comprises a second metal pillar formed on the substrate, and a third LED structure emitting a third color, wherein the third LED structure is located on the second metal pillar.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, the first LED structure is bonded to the substrate by a first metal bonding layer, and/or the second LED structure is bonded to the first metal pillar on the substrate by a second metal bonding layer, and/or the third LED structure is bonded to the second metal pillar on the substrate by a third metal bonding layer.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the lower ends of the first metal posts are electrically connected to contacts on the substrate, the upper ends of the first metal posts are electrically connected to the second metal bonding layer and not lower than the top of the first LED structure, and/or the lower ends of the second metal posts are electrically connected to contacts on the substrate, and the upper ends of the second metal posts are electrically connected to the third metal bonding layer and not lower than the top of the second LED structure.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first LED structure includes a lower conductive layer, an upper conductive layer, and a red LED light emitting layer located between the lower conductive layer and the upper conductive layer, the second LED structure includes a lower conductive layer, an upper conductive layer, and a green LED light emitting layer located between the lower conductive layer and the upper conductive layer, the third LED structure includes a lower conductive layer, an upper conductive layer, and a blue LED light emitting layer located between the lower conductive layer and the upper conductive layer, the upper conductive layers of the first LED structure, the second LED structure, and the third LED structure are electrically connected with the conductive structures, and the lower conductive layers of the first LED structure, the second LED structure, and the third LED structure are electrically connected with corresponding contacts on the substrate, respectively.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the insulating dielectric is made of a dielectric material, such as a solid inorganic material or a plastic material. The solid inorganic material includes SiO₂、Al₃O₃、Si₃N₄、SiCN、HfO₂、Ta₂O₅、TiO₂、ZrO₂、La₂O₃、MgO、 phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), or any combination thereof. The plastic material comprises a polymer such as SU-8, permiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive micro-resist BCL-1200, or any combination of the above.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, a micro lens over the insulating dielectric, and/or a spacer formed at the bottom of the micro lens, at the top of the light exit area, are also included.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the lower end of the conductive structure is located on the substrate but not electrically connected to the contact on the substrate, and the upper end of the conductive structure reaches a position not lower than the top surface of the second or third LED structure, or the upper end of the conductive structure reaches the top surface of the insulating dielectric or the bottom of the micro lens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, the micro lenses include a first micro lens over the first LED structure, a second micro lens over the second LED structure, and a third micro lens over the third LED structure, and the heights of the first micro lens, the second micro lens, and the third micro lens are different, the same, or partially the same.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, a first reflective layer is disposed on a sidewall of the conductive structure.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, a first bottom reflective layer formed between the first LED structure and the first bonding layer, and/or a second bottom reflective layer formed between the second LED structure and the second bonding layer, and/or a third bottom reflective layer formed between the third LED structure and the third bonding layer.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first reflective layer and the bottom reflective layer comprise one or more of a metal layer, a DBR layer, a multi-layer omnidirectional reflector (ODR).

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the DBR layer is a conductive DBR or a dielectric DBR.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first reflective layer is one or more reflective coatings.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure partially overlap each other.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the cross-sectional shapes of the first LED structure, the second LED structure, and the third LED structure are rectangular, circular, square, hexagonal, or elliptical.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, each of the first LED structure, the second LED structure, and the third LED structure includes a first semiconductor epitaxial layer of a first conductivity type, a second semiconductor epitaxial layer of a second conductivity type, and a light emitting layer therebetween.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the plurality of multicolor micro LED pixels are arranged in an n×m pixel array, where N is a positive integer greater than or equal to 1 and M is a positive integer greater than or equal to 2.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, adjacent multicolor micro LED pixels share one or more LED structures.

In some exemplary embodiments or any combination of the foregoing exemplary embodiments of the multicolor micro LED unit, the plurality of multicolor micro LED pixels comprises a first multicolor micro LED pixel and a second multicolor micro LED pixel, the first multicolor micro LED pixel and the second multicolor micro LED pixel sharing a first LED structure, a second LED structure, and/or a third LED structure.

In some exemplary embodiments of the multicolor micro LED unit or any combination of the foregoing exemplary embodiments, the first multicolor micro LED pixel and the second multicolor micro LED pixel-shared first LED structure is electrically connected to a first contact of the first LED structure driving the first multicolor micro LED pixel and a second contact of the first LED structure driving the second multicolor micro LED pixel, the first multicolor micro LED pixel and the second multicolor micro LED pixel-shared second LED structure is electrically connected to a third contact of the second LED structure driving the first multicolor micro LED pixel and a fourth contact of the second LED structure driving the second multicolor micro LED pixel, and/or the first multicolor micro LED pixel and the second multicolor micro LED pixel-shared third LED structure is electrically connected to a fifth contact of the third LED structure driving the first multicolor micro LED pixel and a sixth contact of the third LED structure driving the second multicolor micro LED pixel.

Some exemplary embodiments provide a multicolor micro LED pixel array comprising a plurality of multicolor micro LED pixels arranged in an array, N multicolor micro LED pixels arranged in a line for each row of the array, each multicolor micro LED pixel comprising a first LED structure emitting a first color light, wherein the first LED structure is formed on a substrate, a first metal pillar formed on the substrate, a second LED structure emitting a second color, wherein the second LED structure is located on the first metal pillar, a second metal pillar formed on the substrate, and a third LED structure emitting a third color light, wherein one of the second LED structure and the third LED structure is located on the second metal pillar, wherein one of the second LED structure and the third LED structure in one multicolor micro LED pixel is shared by a left adjacent multicolor micro LED pixel, the other of the second LED structure and the third LED structure in one multicolor micro LED pixel is shared by a right adjacent multicolor micro LED pixel, and the conductive structure is located around the plurality of multicolor micro LED pixels.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the first LED structure is bonded to the substrate by a first metal bonding layer, and/or the second LED structure is bonded to the first metal pillar on the substrate by a second metal bonding layer, and/or the third LED structure is bonded to the second metal pillar on the substrate by a third metal bonding layer.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the lower ends of the first metal posts are electrically connected to contacts on the substrate, the upper ends of the first metal posts are electrically connected to the second metal bonding layer and are not lower than the top of the first LED structure, and/or the lower ends of the second metal posts are electrically connected to contacts on the substrate, and the upper ends of the second metal posts are electrically connected to the third metal bonding layer and are not lower than the top of the second LED structure.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the first LED structure includes a lower conductive layer, an upper conductive layer, and a red LED light emitting layer located between the lower conductive layer and the upper conductive layer, the second LED structure includes a lower conductive layer, an upper conductive layer, and a green LED light emitting layer located between the lower conductive layer and the upper conductive layer, the third LED structure includes a lower conductive layer, an upper conductive layer, and a blue LED light emitting layer located between the lower conductive layer and the upper conductive layer, and the upper conductive layers of the first LED structure, the second LED structure, and the third LED structure are electrically connected to the conductive structures, and the lower conductive layers of the first LED structure, the second LED structure, and the third LED structure are electrically connected to corresponding contacts on the substrate, respectively.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the lower end of the conductive structure is located on the substrate but not electrically connected to the contact on the substrate, and the upper end of the conductive structure reaches a position no lower than the top surface of the second or third LED structure, or the upper end of the conductive structure reaches the bottom of the microlens or the top surface of the insulating dielectric surrounding the LED structure, or directly to the bottom of the top pad and electrically connected to the top pad.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the cross-sectional shapes of the first LED structure, the second LED structure, and the third LED structure are rectangular, circular, square, hexagonal, or elliptical.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the second LED structure is electrically connected to two contacts on the substrate for driving the second LED structure of two adjacent multicolor micro LED pixels, and the third LED structure is electrically connected to two contacts on the substrate for driving the third LED structure of two adjacent multicolor micro LED pixels.

In some exemplary embodiments of the multicolor micro LED pixel array or any combination of the foregoing exemplary embodiments, the conductive structure comprises, for each row of the array, a first horizontal portion and a second horizontal portion located on both sides of the multicolor micro LED pixel along the row direction, a plurality of first vertical portions disposed between adjacent first LED structures, and a plurality of second vertical portions disposed between adjacent second LED structures and third LED structures, wherein one end of the first vertical portion is connected to the first horizontal portion and the other end is directed toward but not in contact with the second LED structure or the third LED structure, wherein one end of the second vertical portion is connected to the second horizontal portion and the other end is directed toward but not in contact with the first LED structure.

Other aspects include assemblies, devices, systems, improvements, methods, and processes, including manufacturing methods, applications, and other techniques related to any of the foregoing.

It should be noted that the various embodiments described above may be combined with any of the 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 one of ordinary skill in the art in view of the drawings, specification, and claims. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter.

Drawings

So that the disclosure may be understood in more detail, a more particular description may be had by reference to the features of the various embodiments, some of which are illustrated in the accompanying drawings. The drawings illustrate only pertinent features of the present disclosure and therefore should not be considered limiting, as the description may allow for other useful features.

Fig. 1 shows a conventional solution for reducing a large divergence angle.

Fig. 2 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention.

Fig. 3 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 2 along line AA in accordance with one embodiment of the invention.

Fig. 4 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 2 along line BB in accordance with one embodiment of the present invention.

Fig. 5 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the invention.

Fig. 6 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 5 along line AA in accordance with one embodiment of the invention.

Fig. 7 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 5 along line BB in accordance with one embodiment of the present invention.

Fig. 8A shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention.

Fig. 8B shows a schematic top view of a multicolor micro LED pixel according to another embodiment of the present invention.

Fig. 9 shows a schematic top view of a multicolor micro LED pixel according to yet another embodiment of the present invention.

Fig. 10 shows a schematic top view of a multicolor micro LED pixel according to yet another embodiment of the present invention.

Fig. 11 shows a schematic top view of a multicolor micro LED pixel with narrow beam width according to one embodiment of the invention.

Fig. 12 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 11 along line AA in accordance with one embodiment of the invention.

Fig. 13 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 11 along line BB in accordance with one embodiment of the present invention.

Fig. 14 shows a schematic cross-sectional view of a process for manufacturing a multi-color micro LED pixel according to one embodiment of the invention.

Fig. 15 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention.

Fig. 16 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line AA in accordance with an embodiment of the invention.

Fig. 17 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line BB in accordance with one embodiment of the present invention.

Fig. 18 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line CC in accordance with one embodiment of the invention.

Fig. 19 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the invention.

Fig. 20 illustrates a cross-sectional view of the multi-color micro LED pixel of fig. 19 along line AA in accordance with one embodiment of the invention.

Fig. 21 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 19 along line BB in accordance with one embodiment of the present invention.

Fig. 22 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the invention.

Fig. 23 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 22 along line AA in accordance with one embodiment of the invention.

Fig. 24 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 22 along line BB in accordance with one embodiment of the present invention.

Fig. 25-27 show the effect of the distance between the emitter and the lens on the LED divergence angle.

Fig. 28-34 illustrate schematic cross-sectional views of multi-color micro LED pixels having at least one inverted trapezoidal LED structure, according to one embodiment of the present invention.

FIG. 35 illustrates a schematic cross-sectional view of a process of manufacturing microlenses of different heights, according to an embodiment of the invention.

Fig. 36 illustrates a top view schematic of four multicolor micro LED pixels sharing one conductive structure, according to one embodiment of the invention.

Fig. 37 shows a schematic top view of a2 x 2 multicolor micro LED pixel sharing one conductive structure according to another embodiment of the present invention.

FIG. 38 illustrates a top view schematic of two multi-color micro LED pixels sharing an LED structure according to one embodiment of the invention.

FIG. 39 illustrates a cross-sectional view of the multi-color micro LED pixel of FIG. 38 along line AA in accordance with one embodiment of the invention.

Fig. 40 illustrates a cross-sectional view of the multi-color micro LED pixel of fig. 38 along line BB in accordance with one embodiment of the present invention.

Fig. 41 illustrates a cross-sectional view of the multi-color micro LED pixel of fig. 38 along line CC according to one embodiment of the invention.

Fig. 42 shows a schematic top view of two multi-color micro LED pixels sharing one LED structure according to another embodiment of the invention.

FIG. 43 illustrates a top view schematic of two multicolor micro LED pixels sharing two LED structures according to one embodiment of the present invention.

FIG. 44 illustrates a cross-sectional view of the multi-color micro LED pixel of FIG. 43 along line AA in accordance with one embodiment of the invention.

Fig. 45 illustrates a cross-sectional view of the multi-color micro LED pixel of fig. 43 along line BB in accordance with one embodiment of the present invention.

In accordance with common practice, the various features shown in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. Moreover, some figures may not depict all of the components of a given system, method, or apparatus. Finally, the same reference numerals may be used to denote the same features throughout the specification and figures.

Detailed Description

Numerous details are described herein to provide a thorough understanding of the example embodiments shown in the 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 recited in the claims. Moreover, well-known processes, components, and materials are not described in detail so as not to unnecessarily obscure the relevant aspects of the embodiments described herein.

In some embodiments, a single multicolor LED pixel includes two or more LED structures. In some embodiments, each LED structure includes at least one LED light emitting layer that emits light of a unique color. When two LED structures are present within a single multi-color LED pixel, the single multi-color LED pixel is capable of emitting light of two colors and a mixture of the two colors. When three LED structures are present within a single multi-color LED pixel, the single multi-color LED pixel is capable of emitting light of three colors and a mixture of the three colors.

Fig. 2 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention. Fig. 3 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 2 along line AA in accordance with one embodiment of the invention. Fig. 4 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 2 along line BB in accordance with one embodiment of the present invention. As shown in fig. 2-4, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a third LED structure 240, a conductive structure 250, and a microlens 260. The first LED structure 220, the second LED structure 230, and the third LED structure 240 are not coaxially stacked. Instead, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are offset from one another from the top.

For convenience, "upward" is used to mean away from the substrate 210, "downward" means toward the substrate 210, as well as other directional terms, such as top, bottom, above, below, directly below, etc., are also construed accordingly. The support substrate 210 is a substrate on which an array of individual driver circuits is prepared. In some embodiments, the driver circuit may also be located in a layer above the substrate 210. Each driver circuit is a pixel driver. In some cases, the driver circuit is a thin film transistor pixel driver or a silicon CMOS pixel driver. In one embodiment, the substrate 210 is a Si substrate. In another embodiment, the support substrate 210 is a transparent substrate, such as a glass substrate. Examples of other substrates include GaAs, gaP, inP, siC, znO and sapphire substrates. The driver circuits form individual pixel drivers to control the operation of individual multi-color micro LED pixels. The circuitry on the substrate 210 includes contacts 211 to each individual driver circuit as well as ground contacts.

In some embodiments, the first LED structure 220 may include a lower conductive layer 221, an upper conductive layer 222, and a red LED light emitting layer 223 between the lower conductive layer 221 and the upper conductive layer 222, the second LED structure 230 may include a lower conductive layer 231, an upper conductive layer 232, and a green LED light emitting layer 233 between the lower conductive layer 231 and the upper conductive layer 232, and the third LED structure 240 may include a lower conductive layer 241, an upper conductive layer 242, and a blue LED light emitting layer 243 between the lower conductive layer 241 and the upper conductive layer 242. It will be appreciated by those skilled in the art that the LED light emitting layer 223 in the first LED structure 220 is not limited to red, the light emitting layer 233 in the second LED structure 230 is not limited to green, and the light emitting layer 243 in the third LED structure 240 is not limited to blue. That is, the light emitting layers 223, 233, 243 may be light emitting layers of any color. The description of red, green and blue light emitting layers or LED structures herein is merely illustrative and not limiting.

In some embodiments, the LED light emitting layers 223, 233, and 243 may include a first semiconductor epitaxial layer of a first conductivity type, a second semiconductor epitaxial layer of a second conductivity type, and a light emitting layer therebetween. The light emitting layer may be, but is not limited to, a multiple quantum well layer. The first conductivity type may be N-type and the second conductivity type may be P-type, or the first conductivity type may be P-type and the second conductivity type may be N-type. The N-type semiconductor epitaxial layer of each of the three color light emitting layers includes, but is not limited to, N-type Si doped GaN, si doped AlGaN, si doped AlGaInP, si doped GaAs, or Si doped AlInP. The P-type semiconductor epitaxial layer includes, but is not limited to, mg doped GaN, mg doped AlGaN, mg doped InGaN, mg doped InAlGaN, mg doped AlInP, mg doped AlGaInP, mg doped GaP, or C doped GaP. The quantum well layers include, but are not limited to, inGaN/GaN cycles, inGaP/AlGaInP cycles.

In some embodiments, the first LED structure 220 may further include an upper connection 224 between the upper conductive layer 222 and the LED light emitting layer 223, and the upper connection is electrically connected to the upper conductive layer 222 and the LED light emitting layer 223. The material of the upper connection 224 is metal, including one or more of Al, au, rh, ag, cr, ti, pt, sn, cu, auSn, tiW.

In some embodiments, the upper and lower conductive layers may be metal layers or conductive transparent layers, such as ITO, FTO, copper layers, formed to improve conductivity and transparency. In another embodiment, the lower conductive layer 221 may be a metal layer to constitute a portion of the first metal bonding layer 271.

Although the term "layer" is used herein to describe some features, 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".

In some embodiments, as shown in fig. 2, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are close to each other, but do not overlap each other.

In some embodiments, the first LED structure 220 is bonded to the substrate 210 through a metal bonding layer 271. The metal bonding layer 271 may be disposed on the substrate 210. In one approach, a metal bonding layer 271 is grown on the substrate 210. In some embodiments, the metal bonding layer 271 and the contacts 211 on the substrate 210 are electrically connected with the first LED structure 220 located above the metal bonding layer 271, functioning like a P-electrode. In some embodiments, the thickness of metal bonding layer 271 is about 0.1 microns to about 3 microns. In a preferred embodiment, the thickness of the metal bonding layer 271 is about 0.3 μm. The metal bonding layer 271 may include an ohmic contact layer and a metal bonding layer. In some cases, the metal bonding layer 271 includes two metal layers. One of the two metal layers is deposited on the bottom of the first LED structure 220. A corresponding bonding metal layer is deposited on the substrate 210. In some embodiments, the composition of metal bonding layer 271 includes Au-Au bonds, au-Sn bonds, au-In bonds, ti-Ti bonds, cu-Cu bonds, or combinations thereof. For example, if au—au bonding is selected, two Au layers require a Cr coating as an adhesive layer and a Pt coating as an anti-diffusion layer, respectively. And the Pt coating is located between the Au layer and the Cr layer. The Cr and Pt layers are located on top and bottom of the two Au layers bonded together. In some embodiments, when the thickness of the two Au layers is approximately the same, au interdiffusion on the two layers bonds the two layers together at high pressure and temperature. Eutectic bonding, thermocompression bonding, and Transient Liquid Phase (TLP) bonding are example techniques that may be used.

In some embodiments, the metal bonding layer 271 may also function as a reflector to reflect light emitted from the overlying LED structure. In some embodiments, the metal bonding layer 271 may include a reflective layer. Furthermore, the reflective layer may comprise stacked reflective sublayers.

In some embodiments, as shown in fig. 4, the second LED structure 230 is bonded to the metal posts 273 on the substrate 210 by a metal bonding layer 272. The third LED structure 240 is bonded to the metal posts 275 on the substrate 210 by a metal bonding layer 274. In some embodiments, the lower ends of the metal posts 273 are electrically connected to contacts 211 on the substrate 210, and the upper ends of the metal posts 273 are electrically connected to the metal bonding layer 272, functioning like a P-electrode. In one approach, metal posts 273 are grown on substrate 210. In some embodiments, the upper end of the metal post 273 is not lower than the top of the first LED structure 220 so that the second LED structure 230 can be bonded to the metal post 273. In some embodiments, the lower ends of the metal posts 275 are electrically connected to contacts 211 on the substrate 210 and the upper ends are electrically connected to a metal bonding layer 274, functioning like a P-electrode. In one approach, metal pillars 275 are grown on substrate 210. In some embodiments, the upper end of the metal stud 275 is not lower than the top of the second LED structure 230 so that the third LED structure 240 may be bonded with the metal stud 275.

In some embodiments, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are directly bonded through a metal bonding layer, and the metal bonding has low requirements on surface flatness. Therefore, the multicolor miniature LED pixel can have the advantages of metal bonding and direct bonding.

In some embodiments, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are embedded within the insulating dielectric 280. The insulating dielectric 280 is transparent to light emitted by the first LED structure 220, the second LED structure 230, and the third LED structure 240. In some embodiments, insulating dielectric 280 is made of a dielectric material, such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material comprises SiO₂、Al₂O₃、Si₃N₄、SiCN、HfO₂、Ta₂O₅、TiO₂、ZrO₂、La₂O₃、MgO、 phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material comprises a polymer such as SU-8, permiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or a bonding adhesive microresister BCL-1200, or any combination of the above. In some embodiments, insulating dielectric 280 may facilitate the passage of light emitted by the LED structure.

As shown in fig. 2, the conductive structure 250 surrounds the periphery of the first LED structure 220, the second LED structure 230, and the third LED structure 240. In some embodiments, the conductive structure 250 may serve as a common electrode to connect the upper conductive layer of each LED structure, functioning like an N electrode. That is, the conductive structures 250 may electrically connect the respective upper conductive layers 242, 232, 222 of the LED structure to the negative pole of an external power source.

However, those skilled in the art will appreciate that the N-electrode and P-electrode of the LED structure are interchangeable. For example, the conductive structures may be used as a common P electrode to connect the P-type epitaxial layers of each LED structure, while the corresponding N-type epitaxial layers of the LED structures are connected to the metal bonding layer.

The upper conductive layers 242, 232, 222 may be flat or have an upward or downward slope due to the height difference between the conductive structures and the LED light emitting layers. For example, in forming the upper conductive layers 242, 232, 222, the upper conductive layers 242, 232, 222 are substantially flat if the height of the conductive structures is the same as the height of the LED light emitting layer, the upper conductive layers 242, 232, 222 include slopes that rise from the edges of the LED light emitting layer toward the conductive structures if the height of the conductive structures is higher than the height of the LED light emitting layer, and the upper conductive layers 242, 232, 222 include slopes that fall from the edges of the LED light emitting layer toward the conductive structures if the height of the conductive structures is lower than the height of the LED light emitting layer. It will be appreciated by those skilled in the art that any shape of the upper conductive layer may be designed according to the specific requirements of the micro LED pixel and fall within the scope of the present invention.

In some embodiments, the lower end of the conductive structure 250 may be located on the substrate 210 but not electrically connected to a contact on the substrate 210, and the upper end of the conductive structure 250 may reach a position not lower than the top surface of the second or third LED structure, preferably, the upper end of the conductive structure 250 may reach the top surface of the insulating dielectric 280 or the bottom of the micro-lens, or directly reach the bottom of the top pad and be electrically connected to the top pad. In some embodiments, the conductive structures 250 may serve as optical isolation structures, so that there is no cross-talk.

In some embodiments, microlenses 260 are formed on the top surface of insulating dielectric 280.

In some embodiments, the micro lens 260 may change the exit light path of individual micro LED pixels according to design requirements, causing the light emitted by the LED device to be more focused or more divergent.

In some embodiments, the microlenses 260 can be made of a variety of materials that are transparent to the wavelengths of light emitted by the individual micro LED pixels. Exemplary transparent materials for microlenses 260 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, and the like. In some embodiments, microlenses 260 are made of photoresist.

In some embodiments, the microlenses 260 are substantially hemispherical in shape.

It will be appreciated that a complete display panel comprises a number of individual pixels and an array of micro-lenses. In addition, there is no need for a one-to-one correspondence between the microlenses and the pixel light sources, nor between the pixel driver circuits (not shown) and the pixel light sources. The pixel light source may also be made of a plurality of individual light elements, such as individual pixel LEDs connected in parallel. In some embodiments, one microlens 260 can cover several single LED pixels without lenses.

The single microlens 260 has a positive optical power and is configured to reduce the divergence or viewing angle of light emitted by the corresponding pixel light source. In one example, the light beam emitted from the pixel light source has a fairly wide original divergence angle. In one embodiment, the original angle of the edge rays of the beam with respect to the vertical axis orthogonal to the substrate 210 is greater than 60 degrees. The light is bent by the micro-lens 260 so that the new edge ray now has a reduced divergence angle. In one embodiment, the reduced angle is less than 30 degrees. The microlenses in the microlens array are typically identical. Examples of microlenses include spherical microlenses, aspherical microlenses, fresnel microlenses, and cylindrical microlenses.

The microlenses 260 generally have a planar side and a curved side. In fig. 3 and 4, the bottom of the microlens 260 is a flat side and the top is a curved side. Typical shapes of the base of each microlens 260 include circular, square, rectangular, and hexagonal. The individual microlenses in the microlens array of the display panel may be the same or different in shape, curvature, optical power, size, base, pitch, etc. In some embodiments, the microlenses 260 conform to the shape of the individual LED pixels. In one example, the base shape of the microlens 260 is the same as the shape of a single LED pixel. In another example, the shape of the base of the microlens 260 is different from the shape of a single LED pixel, e.g., the circular base of the microlens has the same width as a single LED pixel, but is smaller in area because the microlens base is circular and the base of a single LED pixel is square. In some embodiments, the microlens base area is smaller than the area of the pixel light source. In some embodiments, the area of the microlens base is equal to or greater than the area of the pixel light source.

In some embodiments, the brightness enhancement effect is achieved by integrating a microlens array onto the display panel. In some examples, the brightness with the microlens array is 4 times greater than the brightness without the microlens array in the direction perpendicular to the display surface due to the condensing effect of the microlenses. In alternative embodiments, the brightness enhancement factor may vary according to different designs of microlens arrays and optical spacers. For example, a factor greater than 8 may be implemented.

The microlenses may be fabricated by a variety of fabrication methods, including deposition, patterning, etching, and the like.

Fig. 5 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the invention. Fig. 6 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 5 along line AA in accordance with one embodiment of the invention. Fig. 7 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 5 along line BB in accordance with one embodiment of the present invention. As shown in fig. 5-7, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a third LED structure 240, a conductive structure 250, and a microlens 260. The multi-color micro LED pixel shown in fig. 5-7 differs from the multi-color micro LED pixel shown in fig. 2-4 in that the multi-color micro LED pixel shown in fig. 5-7 may further include one or more of a reflective layer 251, a bottom reflective layer 501, a bottom reflective layer 502, and a bottom reflective layer 503.

In some embodiments, as shown in fig. 6 and 7, a reflective layer 251 is disposed on sidewalls of the conductive structure 250. In some embodiments, the conductive structure 250 substantially surrounds the first LED structure, the second LED structure, and the third LED structure such that light emitted from the LED structures toward the conductive structure 250 is reflected by the reflective layer 251 and exits from the top surface of the individual LED pixel.

In some embodiments, the conductive structure with the reflective layer 251 may be fabricated by a combination of deposition, photolithography, and etching processes. In some embodiments, the conductive structure with the reflective layer 251 may be fabricated by other suitable methods.

In some embodiments, the reflective layer 253 can be a metal layer with high reflectivity comprising one or more metals, such as Pt, rh, al, au, and Ag, a stacked DBR layer comprising layers of TiO ₂/SiO₂, or any other layer with total reflection properties, including a multilayer omnidirectional reflector (ODR), or a combination of the above.

In some embodiments, the reflective layer 251 may be one or more reflective coatings disposed on sidewalls of the conductive structure 250. The bottom of each of the one or more reflective coatings is not in contact with the corresponding LED structure. The one or more reflective coatings may reflect light emitted from the light emitting region, thereby improving the brightness and light emitting efficiency of the micro LED panel or display. For example, light emitted from the light emitting region may reach and be reflected upward by one or more reflective coatings.

The material of the one or more reflective coatings may be highly reflective, having a reflectivity of greater than 60%, 70% or 80%, and thus may reflect a substantial portion of the light emitted from the light emitting region. In some embodiments, the one or more reflective coatings may include one or more metallic conductive materials having high reflectivity. In these embodiments, the one or more metallic conductive materials may include one or more of aluminum, gold, or silver. In other embodiments, one or more of the reflective coatings may be multi-layered. More specifically, the one or more reflective coatings may include one or more reflective material layers and one or more dielectric material layers stacked. For example, the one or more reflective coatings may include one layer of reflective material and one layer of dielectric material. In other embodiments, the one or more reflective coatings may include two layers of reflective material and one layer of dielectric material between the two layers of reflective material. In some other embodiments, however, one or more reflective coatings may include two layers of dielectric material and one layer of reflective material positioned between the two layers of dielectric material. In some embodiments, the multilayer structure may include two or more metal layers, which may include one or more of TiAu, crAl, or TiWAg.

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 layer of dielectric material, a metal layer, and a TCO layer. In some embodiments, one or more reflective coatings may include two or more layers of dielectric material, alternately arranged to form a Distributed Bragg Reflector (DBR). For example, the one or more reflective coatings may include a layer of dielectric material, a metal layer, and a transparent dielectric layer. The transparent dielectric layer may include one or more of SiO ₂、Si₃N₄、Al₂O₃ or TiO ₂. The one or more reflective coatings may also include a layer of dielectric material, TCO, and DBR. In other embodiments, the one or more reflective coatings may include one or more metallic conductive materials having 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 layer 251 may be a conductive reflective layer or a dielectric reflective layer.

In some embodiments, as shown in fig. 6 and 7, bottom reflective layer 501, bottom reflective layer 502, and bottom reflective layer 503 are disposed between the metal bonding layer and the LED structure. The materials and manufacturing process of the bottom reflective layer are similar to those of the reflective layer 251 and will not be described in detail for the sake of simplicity. When the bottom reflective layer is a conductive reflective layer, the bottom reflective layer may be a continuous layer or a discontinuous layer having one or more gaps. When the bottom reflective layer is a dielectric reflective layer, the bottom reflective layer may be a discontinuous layer having one or more gaps in which a conductive material is formed to ensure that the first LED structure and the substrate may be electrically connected.

Fig. 8A shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention. As shown in fig. 8A, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a third LED structure 240, a conductive structure 250, and a microlens 260. The multicolor micro LED pixel shown in fig. 8 is different from the multicolor micro LED pixel shown in fig. 2-4 in that the first LED structure 220, the second LED structure 230, and the third LED structure 240 partially overlap each other. The advantage of this configuration is that the three LED structures are more closely arranged, which is advantageous for reducing the size of a single multi-color micro LED pixel.

Fig. 8B shows a schematic top view of a multicolor micro LED pixel according to another embodiment of the present invention. As shown in fig. 8B, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a third LED structure 240, a conductive structure 250, and a microlens 260. The overlapping area between the first LED structure 220, the second LED structure 230, and the third LED structure 240 is increased as compared to the multicolor micro LED pixel shown in fig. 8A, which is advantageous for further reducing the size of the single multicolor micro LED pixel.

Fig. 9 shows a schematic top view of a multicolor micro LED pixel according to yet another embodiment of the present invention. As shown in fig. 9, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a conductive structure 250, and a microlens 260. In contrast to the multicolor micro LED pixel shown in fig. 8A, the multicolor micro LED pixel shown in fig. 9 includes only two LED structures. In some embodiments, the first LED structure 220 and the second LED structure 230 may be red-green bi-color, red-blue bi-color, green-blue bi-color, or a combination of other bi-colors.

Fig. 10 shows a schematic top view of a multicolor micro LED pixel according to yet another embodiment of the present invention. As shown in fig. 10, the multicolor micro LED pixel includes a substrate 210, a first LED structure 220, a second LED structure 230, a third LED structure 240, a conductive structure 250, and a microlens 260. The cross section of the LED structure is circular.

However, it will be appreciated by those skilled in the art that the cross-section of the LED structure may be of any shape.

Fig. 11 shows a schematic top view of a multicolor micro LED pixel with narrow beam width according to one embodiment of the invention. Fig. 12 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 11 along line AA in accordance with one embodiment of the invention. Fig. 13 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 11 along line BB in accordance with one embodiment of the present invention. As shown in fig. 11-13, the multicolor micro LED pixel includes a substrate 1110, a first LED structure 1120, a second LED structure 1130, a third LED structure 1140, a conductive structure 1150, microlenses 1160, and spacers 1170. The multicolor micro LED pixel shown in fig. 11 differs from the pixel shown in fig. 2 by a spacer 1170.

In some embodiments, spacers 1170 are formed at the bottom of the microlenses 1160, at the top of the light exit region.

The spacer 1170 is an optically transparent layer that is formed to maintain the position of the microlens 1160 relative to the pixel light source. The spacer 1170 can be made of various materials that are transparent to the light of each wavelength emitted by the pixel light source. Exemplary transparent materials for spacer 1170 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, and the like. In some embodiments, the spacers 1170 are made of photoresist. In some embodiments, the spacers 1170 are of the same material as the microlenses 1160. In some embodiments, the spacer 1170 is of a different material than the microlens 1160.

In some embodiments, when forming the microlenses 1160, the spacer layer 1170 can be formed using the same material in the same process as the microlenses 1160.

In some embodiments, a reflective layer 1171 is disposed on a sidewall of the spacer 1170. The structure, materials, and manufacturing method of the reflective layer 1171 are similar to those of the reflective layer 251, and will not be described in detail for the sake of simplicity.

In some embodiments, the spacer 1170 has a thickness of about 2 μm to 10 μm as measured from the top surface of the pixel light source, which helps achieve a narrow beam width.

In the above and other embodiments of the invention, the LED structure is embedded within the insulating dielectric. For a conventional SiO ₂/SiN insulating dielectric, H ₂ from the SiH ₄ gas precursor can passivate pGaN, resulting in a high Vf. Thus, it may be beneficial to avoid the use of SiH ₄ -based precursors. In some embodiments, the insulating dielectric may be made of a dielectric material such as a solid inorganic material. In some embodiments, the solid inorganic material comprises Al₂O₃、HfO₂、Ta₂O₅、TiO₂、ZrO₂、La₂O₃、MgO, or the like.

As shown in fig. 14, in step S1, a first LED structure 1420 is formed on a substrate 1410. Specifically, step S1 may include forming a first lower conductive layer 1421 on the first LED light emitting layer 1423, bonding the first LED light emitting layer 1423 to the substrate 1410, forming a first mesa by etching the first LED light emitting layer 1423, forming an isolation layer 1424 around the first mesa, and forming a first upper conductive layer 1422 on the first LED light emitting layer 1423.

In step S2, an insulating dielectric 1480 surrounding the first LED structure 1420 and covering the top surface of the first LED structure 1420 is filled, and a conductive structure 1450, a first metal pillar 1473, and a second metal pillar 1475 are formed on the substrate 1410 flush with the top surface of the insulating dielectric 1480.

In step S3, a second lower conductive layer 1431 is formed on the second LED light emitting layer 1433, bonding the second LED light emitting layer 1433 to the first metal posts 1473.

In step S4, a second mesa is formed by etching the second LED light emitting layer 1433, an isolation layer 1434 is formed around the second mesa, and a second upper conductive layer 1432 is formed on the second LED light emitting layer 1423.

In step S5, an insulating dielectric 1480 surrounding the second LED structure 1430 and covering the top surface of the second LED structure 1430 is filled, a conductive structure 1450 and a second metal pillar 1475 are formed on the substrate 1410 flush with the top surface of the insulating dielectric 1480, a third lower conductive layer 1441 is formed on the third LED light emitting layer 1443, and the third LED light emitting layer 1443 is bonded to the second metal pillar 1475.

In step S6, a third mesa is formed by etching the third LED light emitting layer 1443, an isolation layer 1444 is formed around the third mesa, and a third upper conductive layer 1442 is formed on the third LED light emitting layer 1443.

It will be appreciated by those skilled in the art that the above method steps are merely examples, and that in other embodiments of the invention, different steps and processes may be employed.

Fig. 15 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the present invention. Fig. 16 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line AA in accordance with an embodiment of the invention. Fig. 17 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line BB in accordance with one embodiment of the present invention. Fig. 18 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 15 along line CC in accordance with one embodiment of the invention. As shown in fig. 15-18, the multicolor micro LED pixel includes a substrate 1510, a first LED structure 1520, a second LED structure 1530, a third LED structure 1540, a conductive structure 1550, and microlenses 1560. The first LED structure 1520, the second LED structure 1530, and the third LED structure 1540 are not coaxially stacked. Instead, the first LED structure 1520, the second LED structure 1530, and the third LED structure 1540 are offset from each other from the top.

As shown in fig. 15-18, the multicolor micro LED pixel further includes a first air gap 1525 surrounding the first LED structure 1520, a second air gap 1535 surrounding the second LED structure 1530, a third air gap 1545 surrounding the third LED structure 1540, and a central electrode 1590 located between the first LED structure 1520, the second LED structure 1530, and the third LED structure 1540. When light enters low refractive index air (n≡1) from a high refractive index material (such as SiN, n=1.9), total reflection occurs at the interface of the air gap and the high refractive index material, so that the air gap has the effects of optical isolation and improvement of light extraction efficiency.

In some embodiments, the lower ends of the air gaps 1525, 1535 and 1545 may reach the substrate 1510 and the upper ends may reach a position no lower than the top surface of the second or third LED structure, preferably the upper ends of the air gaps may reach the top surface of the insulating dielectric or the bottom of the micro-lenses or directly to the bottom of the top pads. The cross-sectional shape of the air gaps 1525, 1535, and 1545 is similar to the cross-sectional shape of the first through third LED structures. That is, if the LED structure is circular, the cross-sections of the air gaps 1525, 1535, and 1545 may be circular, and if the LED structure is rectangular, the cross-section of the air gaps may be rectangular. No air gap is formed at the peripheral portion of the LED structure adjacent to the central electrode 1590. That is, each air gap 1525, 1535, and 1545 has a notch in the peripheral portion of the LED structure adjacent to the central electrode 1590 such that each upper conductive layer of the first LED structure 1520, the second LED structure 1530, and the third LED structure 1540 can be electrically connected with the central electrode 1590 through the notch.

In some embodiments, the lower end of the central electrode 1590 may be located on the substrate 1510 but not in electrical connection with the contacts on the substrate 1510, the upper end of the central electrode 1590 may reach a position no lower than the top surface of the second or third LED structure, preferably the upper end of the central electrode 1590 may reach the top surface of the insulating dielectric or the bottom of the micro-lens, or directly to the bottom of the top pad and in electrical connection with the top pad.

Fig. 19 shows a schematic top view of a multicolor micro LED pixel according to one embodiment of the invention. Fig. 20 illustrates a schematic cross-sectional view of the multicolor micro LED pixel of fig. 19 along line AA in accordance with an embodiment of the present invention. Fig. 21 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 19 along line BB in accordance with one embodiment of the present invention. As shown in fig. 19-21, the multicolor micro LED pixel includes a substrate 1910, a first LED structure 1920, a second LED structure 1930, a third LED structure 1940, a conductive structure 1950, a first microlens 1961 over the first LED structure 1920, a second microlens 1962 over the second LED structure 1930, and a third microlens 1963 over the third LED structure 1940. The first, second, and third LED structures 1920, 1930, 1940 are not coaxially stacked. Instead, the first, second, and third LED structures 1920, 1930, 1940 are offset from one another from the top.

The multi-color micro LED pixel shown in fig. 19-21 is similar to the multi-color micro LED pixel shown in fig. 2, except that each LED structure has a separate microlens.

As shown in fig. 19-21, the cross-sectional shapes of the first, second, and third LED structures 1920, 1930, 1940 may be rectangular. However, it will be appreciated by those skilled in the art that the cross-section of the LED structure may be of any shape. For example, as shown in fig. 22-24, the cross-sectional shapes of the first LED structure 2220, the second LED structure 2230, and the third LED structure 2240 may be circular.

In the embodiment shown in fig. 19-24, each LED structure has individual microlenses, and each microlens may have a different height. This therefore corresponds to each LED structure being on top, thereby reducing the chance of light emitted by the underlying LED being reflected and absorbed by the light isolating and electrical connection structures and improving LEE (light extraction efficiency). This configuration allows each LED to be designed with the proper lens size and spacer height for optimal light collection.

Fig. 25-27 show the effect of the distance between the emitter and the lens on the LED divergence angle. As shown in fig. 25, the illuminant is located at the focal point and most of the light that can enter the lens exits the lens at an angle that is approximately parallel to the central axis of the lens. As shown in fig. 26, the illuminant is located inside the focal point, and the proportion of light that can enter the lens increases, but most of the light that is emitted from the lens is emitted at an angle that deviates from the central axis of the lens. As shown in fig. 27, the light emitter is located outside the focal point, and the proportion of light that can enter the lens is reduced, but most of the light that is emitted from the lens is emitted at an angle toward the central axis of the lens.

In the above embodiment, the cross-sectional shape of each LED structure is trapezoidal, i.e., the top area of the LED structure is smaller than the bottom area. However, in other embodiments of the present invention, as shown in FIGS. 28-33, the cross-sectional shape of some LED structures may be inverted trapezoidal, i.e., the top area of the LED structure is greater than the bottom area. LED structures with inverted trapezoids have higher LEEs (light extraction efficiency). Furthermore, reflective layers may be provided at the bottom and sidewalls of the LED structure, which will also improve LEEs.

As shown in fig. 28, only the cross-sectional shape of the second LED structure 2820 is inverted trapezoidal, while the cross-sectional shapes of the first LED structure 2810 and the third LED structure 2830 are trapezoidal. Reflective layers 2821 are disposed on the bottom and sidewalls of the second LED structure 2820.

As shown in fig. 29, the cross-sectional shape of the second and third LED structures 2920, 2930 is inverted trapezoidal, while the cross-sectional shape of the first LED structure 2910 is trapezoidal. Two reflective layers 2921, 2931 are provided on the bottom and sidewalls of the second and third LED structures 2920, 2930.

As shown in fig. 30, only the cross-sectional shape of the third LED structure 3030 is inverted trapezoidal, while the cross-sectional shapes of the first and second LED structures 3010, 3020 are trapezoidal. The reflective layer 3031 is disposed on the bottom and sidewalls of the third LED structure 3030.

As shown in fig. 31, only the cross-sectional shape of the first LED structure 3110 is inverted trapezoidal, while the cross-sectional shapes of the second LED structure 3120 and the third LED structure 3130 are trapezoidal. The reflective layer 3111 is disposed on the bottom and sidewalls of the first LED structure 3110.

As shown in fig. 32, the cross-sectional shape of the first and second LED structures 3210, 3220 is an inverted trapezoid, and the cross-sectional shape of the third LED structure 3230 is a trapezoid. Two reflective layers 3211, 3221 are provided on the bottom and sidewalls of the first and second LED structures 3210, 3220.

As shown in fig. 33, the cross-sectional shapes of the first to third LED structures 3310, 3320, 3330 are all inverted trapezoids. Three reflective layers 3311, 3321, 3331 are disposed on the bottom and sidewalls of the first to third LED structures 3310, 3320, 3330.

As shown in fig. 34, the cross-sectional shape of the first and third LED structures 3410, 3430 is an inverted trapezoid, while the cross-sectional shape of the second LED structure 3420 is a trapezoid. Two reflective layers 3411, 3431 are disposed on the bottom and sidewalls of the first and third LED structures 3410, 3430.

In step S1, a dielectric layer 3510 is formed on the substrate of the fabricated LED structure and associated conductive structure, and a plurality of hemispherical photoresist bumps 3521, 3522, 3523 are formed on the dielectric layer directly above the first, second and third LED structures. In some embodiments of the present invention, the photoresist bumps 3521, 3522, 3523 having predetermined dimensions and curvatures may be formed through a photolithography, reflow, or imprinting process.

In step S2, an etching process is performed to form a plurality of hemispherical bump structures 3511, 3512, 3513 on the dielectric layer 3510. During etching, the etch rate of dielectric layer 3510 is substantially the same as the etch rate of the photoresist, so that after etching is completed, the shape of the photoresist is replicated onto dielectric layer 3510.

In step S3, a photoresist layer is formed on the hemispherical bump structure 3511 on the dielectric layer 3510 to a certain thickness. The hemispherical bump structures 3512, 3513 are not covered by photoresist layers. In some embodiments of the invention, the photoresist layer may be of any shape. In an embodiment of the present invention, a certain thickness of photoresist may be formed on the entire surface of the dielectric layer 3510 through processes such as spin coating and imprinting, and then the photoresist over the hemispherical bump structures 3512, 3513 is removed while the photoresist over the hemispherical bump structures 3511 remains. An etching process is performed to reduce the heights of the hemispherical bump structures 3512 and 3513 by a predetermined distance, and then the photoresist remaining on the hemispherical bump structure 3511 is removed.

In step S4, a photoresist layer is formed with a certain thickness on the hemispherical bump structures 3511 and 3512 on the dielectric layer 3510. The hemispherical bump structure 3513 is not covered by the photoresist layer. An etching process is performed to reduce the height of the hemispherical bump structure 3513 by a predetermined distance, and then the photoresist remaining on the hemispherical bump structures 3511 and 3512 is removed.

In some embodiments, multiple multicolor micro LED pixels may share one conductive structure. For example, fig. 36 shows a schematic top view of four multicolor micro LED pixels sharing one conductive structure, according to one embodiment of the present invention.

As shown in fig. 36, the conductive structure 3650 is a square ring and surrounds the four multi-color micro LED pixels 3610, 3620, 3630, 3640. Each multicolor micro LED pixel is similar to the multicolor micro LED pixel shown in fig. 2, except that four multicolor micro LED pixels 3610, 3620, 3630, 3640 share a common conductive structure 3650. The LED structure in each pixel is circular in cross-section.

In some embodiments, conductive structure 3650 may serve as a common electrode connecting the upper conductive layer of the LED structure in each micro LED pixel to the negative electrode of an external power source. In some embodiments, conductive structure 3650 may also be referred to as a top electrode or an N-electrode.

In some embodiments, the number of multicolor micro LED pixels sharing one conductive structure may be 1 x 2, 2 x 3, 3x 3. In other words, the multicolor micro LED pixels sharing one conductive structure may be arranged in an n×m pixel array, where N is a positive integer greater than or equal to 1 and M is a positive integer greater than or equal to 2.

Fig. 37 is a schematic top view of a2 x 2 multicolor micro LED pixel sharing a conductive structure according to another embodiment of the present invention. The structure shown in fig. 37 is similar to that shown in fig. 36, and only differences are described for simplicity of explanation. As shown in fig. 37, the LED structure in each pixel is rectangular in cross section, and one microlens 3760 covers 2×2 multicolor micro LED pixels.

Those skilled in the art will appreciate that the microlenses may have a variety of arrangements, such as one microlens 3660 covering one pixel as shown in fig. 36, one microlens covering multiple pixels as shown in fig. 37, or one microlens covering one LED structure, etc.

In some embodiments, each multicolor micro LED pixel may include a plurality of LED structures, and adjacent multicolor micro LED pixels may share one or more LED structures. The LED structure shared by the two or more multi-color micro LED pixels is electrically connected to a plurality of contacts on the IC substrate for driving corresponding ones of the two or more multi-color micro LED pixels. The LED structure shared by two or more multicolor micro LED pixels may be of any color.

FIG. 38 illustrates a top view schematic of two multi-color micro LED pixels sharing an LED structure according to one embodiment of the invention. FIG. 39 illustrates a cross-sectional view of the multi-color micro LED pixel of FIG. 38 along line AA in accordance with one embodiment of the invention. Fig. 40 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 38 along line BB in accordance with one embodiment of the present invention. Fig. 41 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 38 along line CC in accordance with one embodiment of the invention. As shown in fig. 38-41, the first pixel 3810 and the second pixel 3820 may share a third LED structure 3803. The first pixel 3810 may also include a first LED structure 3811 and a second LED structure 3812 that are not shared by other pixels. The second pixel 3820 may also include a first LED structure 3821 and a second LED structure 3822 that are not shared by other pixels. The small circles in the center of each LED structure represent contacts on the IC substrate below the LED structure, which are shown in top view for illustrative purposes only. The third LED structure 3803 shared by the first pixel 3810 and the second pixel 3820 is electrically connected to a contact 3813 for driving the third LED structure in the first pixel 3810 and a contact 3823 for driving the third LED structure in the second pixel 3820. The third LED structure 3803 is bonded to the two metal posts 3814 and 3824 on the substrate by a metal bonding layer. The lower ends of the metal posts 3814 are electrically connected to contacts 3813 on the substrate, and the upper ends of the metal posts 3814 are electrically connected to the metal bonding layer, functioning as P-electrodes of the third LED structure in the first pixel 3810. The lower ends of the metal posts 3824 are electrically connected to contacts 3823 on the substrate, and the upper ends of the metal posts 3824 are electrically connected to the metal bonding layer, functioning as P-electrodes of the third LED structure in the second pixel 3820.

Fig. 42 shows a schematic top view of two multi-color micro LED pixels sharing one LED structure according to another embodiment of the present invention. The structure shown in fig. 42 is similar to the structure shown in fig. 38, with the only difference that the LED structure in each pixel is rectangular in cross-section.

FIG. 43 illustrates a top view schematic of two multicolor micro LED pixels sharing two LED structures according to one embodiment of the present invention. FIG. 44 illustrates a cross-sectional view of the multicolor micro LED pixel of FIG. 43 along line AA in accordance with one embodiment of the present invention. Fig. 45 illustrates a schematic cross-sectional view of the multi-color micro LED pixel of fig. 43 along line BB in accordance with one embodiment of the present invention. As shown in fig. 43-45, the multicolor micro LED pixels are arranged in an array. For example, N multicolor LED pixels are arranged in a line to form a row of the array. For the first row, the third LED structure 4303 is shared by the first pixel 4310 and the second pixel 4320, and the second LED structure 4302 is shared by the second pixel 4320 and the third pixel 4330. Each pixel may also include a first LED structure that is not shared by other pixels. That is, each pixel may include three LED structures, one shared by the left-hand adjacent pixels, one shared by the right-hand adjacent pixels, and one not shared by the other pixels. The small circles in the center of each LED structure represent contacts on the IC substrate below the LED structure, which are shown in top view for illustrative purposes only.

The third LED structure 4303 shared by the first pixel 4310 and the second pixel 4320 is electrically connected to a contact 4313 for driving the third LED structure in the first pixel 4310 and a contact 4323 for driving the third LED structure in the second pixel 4320. The third LED structure 4303 is bonded to the two metal posts 4314 and 4324 on the substrate by a metal bonding layer. The lower ends of the metal posts 4314 are electrically connected to contacts 4313 on the substrate, and the upper ends of the metal posts 4314 are electrically connected to the metal bonding layer, serving as P-electrodes of the third LED structure in the first pixel 4310. The lower ends of the metal posts 4324 are electrically connected to contacts 4323 on the substrate, and the upper ends of the metal posts 4324 are electrically connected to the metal bonding layer, serving as P-electrodes of the third LED structure in the second pixel 4320.

The second LED structure 4302 shared by the second pixel 4320 and the third pixel 4320 is electrically connected to a contact 4322 for driving the second LED structure in the second pixel 4320 and a contact 4332 for driving the second LED structure in the third pixel 4330. The second LED structure 4302 is bonded to the two metal posts 4325 and 4335 on the substrate by a metal bonding layer. The lower ends of the metal posts 4325 are electrically connected to contacts 4322 on the substrate, and the upper ends of the metal posts 4325 are electrically connected to the metal bonding layer, acting as P-electrodes of the second LED structure in the second pixel 4320. The lower ends of the metal posts 4335 are electrically connected to contacts 4332 on the substrate, and the upper ends of the metal posts 4335 are electrically connected to the metal bonding layer, acting as P-electrodes of the second LED structure in the third pixel 4330.

In some embodiments, to achieve better light isolation, in a multicolor micro LED pixel array, the conductive structure 4350 may include, for each row of pixels, a first horizontal portion 4351 and a second horizontal portion 4352 located on both sides of the pixel in the pixel row direction, a plurality of first vertical portions 4353 disposed between adjacent first LED structures, and a plurality of second vertical portions 4354 disposed between adjacent second and third LED structures. One end of the first vertical portion 4353 is connected to the first horizontal portion 4351, and the other end faces the second LED structure or the third LED structure but is not in contact with the second LED structure or the third LED structure. One end of the second vertical portion 4354 is connected to the second horizontal portion 4352, and the other end faces the first LED structure but is not in contact with the first LED structure.

It will be appreciated by those skilled in the art that a multicolor micro LED pixel according to one embodiment of the present invention may comprise any number of LED structures of the same or different colors. For example, a multicolor micro LED pixel may include four, five, or six LED structures.

Each dimension of the micro LED chip is no more than 1 centimeter (cm), preferably no more than 20 micrometers (μm). The micro LED structures are formed in array form in the micro LED chip, and the resolution is, for example, 720×480, 640×480, 1920×1080, 1280×720, 2k or 4k. The diameter of the micro LED structure is at the nano level, e.g. 20nm to 100nm.

The micro LED chip includes an Integrated Circuit (IC) backplate and a micro LED array. The micro LED array includes a plurality of micro LEDs. Each micro LED may form at least a portion of a pixel element on the micro LED chip.

In some embodiments, the IC backplate may be electrically connected to each micro LED of the array of micro LEDs by a separate metal interconnect. In some embodiments, each micro LED may be individually electrically controlled by the IC backplane. In some embodiments, the IC backplate may be electrically connected to the electrodes of the micro LED chip by metal interconnects. In some embodiments, a dielectric layer may be formed in the gaps between the micro LEDs. In some embodiments, a dielectric layer may also be formed in the gaps between the interconnects.

In some embodiments, each micro LED in the array of micro LEDs may include a micro mesa structure. In some embodiments, the micro mesa structure may include a first type epitaxial layer, a light emitting layer, and a second type epitaxial layer from bottom to top. I.e. of these three layers, the first type epitaxial layer is closest to the IC backplate, the light emitting layer is located above the first type epitaxial layer and furthest from the IC backplate, and the second type epitaxial layer is located above the light emitting layer and furthest from the IC backplate. In some embodiments, the light emitting layer is formed of several stacked quantum well layers, in particular superlattice stacked quantum well layers. Preferably, the superlattice-stacked quantum well layers include a plurality of pairs of quantum well layers stacked with quantum barrier layers. In some embodiments, the first type epitaxial layer is a semiconductor material having a first conductivity type and includes a plurality of semiconductor layers. The host material of the first type epitaxial layer may be, but is not limited to, ga, N, as, P, in or Al. In addition, the first type epitaxial layer may include, but is not limited to, a waveguide layer, a confinement layer, a transition layer, and a window layer from top to bottom, and furthermore, an ohmic contact layer may be formed under the window layer. In some embodiments, the second type epitaxial layer is a semiconductor material having a second conductivity type and includes a number of semiconductor layers. The host material of the second type epitaxial layer may be, but is not limited to, ga, N, as, P, in or Al based materials. In addition, the first type epitaxial layer may include, but is not limited to, a confinement layer and a waveguide layer from top to bottom, and furthermore, in some embodiments, an ohmic contact layer may be, but is not limited to, formed on the confinement layer.

In some embodiments, a top conductive layer may be formed on the top surface of the micro LED array. In some embodiments, the top conductive layer may be shared by all of the micro LEDs in the array of micro LEDs. In some embodiments, the light emitting layer may include at least one quantum well layer. In some embodiments, the micro LED array may comprise a single layer micro LED structure. In some embodiments, the micro LED array may include a vertically stacked multi-layer micro LED structure.

In some embodiments, the micro LED array may include blue micro LEDs. In some embodiments, the pitch of the micro LED array (i.e., the minimum center-to-center distance between micro LEDs) may be about 2 μm to about 50 μm. In some embodiments, the number of pixels in a micro LED chip may be thousands to millions or more.

Although the detailed description contains many specifics, these should not be construed as limitations on the scope of the invention, but merely as exemplifications of different aspects of the invention. It is to be understood that the scope of the present invention includes other embodiments not discussed in detail above. For example, the above method may be applied to the integration of functional devices other than LEDs and OLEDs with control circuits of non-pixel drivers. Examples of non-LED devices include Vertical Cavity Surface Emitting Lasers (VCSELs), photodetectors, microelectromechanical systems (MEMS), silicon photonics, power electronics, and distributed feedback lasers (DFBs). Examples of other control circuits include current drivers, voltage drivers, transimpedance amplifiers, and logic circuits.

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 readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

The features of the present invention may be implemented, used, or aided by a computer program product, such as a storage medium (media) or computer-readable storage medium (media) having instructions stored thereon/in which can be used to program a processing system to perform any of the features set forth herein. The storage medium may include, but is not limited to, high-speed random access memory (e.g., DRAM, SRAM, DDR RAM, or other random access solid state storage devices), and may include non-volatile memory (e.g., one or more magnetic disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid state storage devices). The memory optionally includes one or more storage devices remotely located from the CPU. The memory or a non-volatile storage device within the memory includes a non-transitory computer-readable storage medium.

Features of the present invention may be stored on any machine-readable medium and integrated into software and/or firmware for controlling the hardware of the processing system and enabling the processing system to interact with other mechanisms which utilize 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.

It will be understood that, although the terms "first," "second," and the like 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.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the claims. As used in the description of the embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is also to be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

As used herein, the term "if" may be interpreted to mean "in the context of" when..once..or "in response to detection," depending on the context, the stated precondition is true. Similarly, the phrase "if it is determined that a prerequisite of a statement is true" or "if a prerequisite of a statement is true" or "when a prerequisite of a statement is true" may be interpreted to mean that, depending on the context, "when determining" or "in response to a determination" or "upon a determination" or "when detecting" or "in response to a detection", the prerequisite of a statement is true.

For ease of explanation, the above description has been described with reference to specific embodiments. However, the illustrative discussions above are 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 teaching. The embodiments were chosen and described in order to best explain the principles of operation and the practical application, thereby enabling others skilled in the art to understand them.

Claims

1. A multi-color micro LED unit, comprising:

A plurality of multi-color micro-LED pixels, each multi-color micro-LED pixel comprising: a first LED structure emitting a first color light, wherein the first LED structure is formed on a substrate; a first metal pillar formed on the substrate; a second LED structure emitting a second color light, wherein the second LED structure is located on the first metal pillar; and...

Conductive structure surrounding the plurality of multicolor micro-LED pixels.

2. The multi-color micro LED unit according to claim 1, characterized in that each multi-color micro LED pixel further comprises:

The second metal pillar formed on the substrate; and

A third LED structure that emits a third color of light, wherein the third LED structure is located on the second metal pillar.

3. The multicolor micro LED unit according to claim 1 or 2, characterized in that:

The first LED structure is bonded to the substrate via a first metal bonding layer; and/or

The second LED structure is bonded to a first metal pillar on the substrate via a second metal bonding layer; and/or

The third LED structure is bonded to the second metal pillar on the substrate through a third metal bonding layer.

4. The multicolor micro LED unit according to claim 3, characterized in that:

The lower end of the first metal pillar is electrically connected to a contact on the substrate, and the upper end of the first metal pillar is electrically connected to the second metal bonding layer, and is not lower than the top of the first LED structure; and/or

The lower end of the second metal pillar is electrically connected to a contact on the substrate, and the upper end of the second metal pillar is electrically connected to the third metal bonding layer, and is not lower than the top of the second LED structure.

5. The multicolor micro LED unit according to claim 2, characterized in that:

The first LED structure includes a lower conductive layer, an upper conductive layer, and a red LED light-emitting layer located between the lower conductive layer and the upper conductive layer;

The second LED structure includes a lower conductive layer, an upper conductive layer, and a green LED light-emitting layer located between the lower conductive layer and the upper conductive layer; the third LED structure includes a lower conductive layer, an upper conductive layer, and a blue LED light-emitting layer located between the lower conductive layer and the upper conductive layer; and

The upper conductive layers of the first LED structure, the second LED structure, and the third LED structure are electrically connected to the conductive structure, and the lower conductive layers of the first LED structure, the second LED structure, and the third LED structure are respectively electrically connected to corresponding contacts on the substrate.

6. The multicolor micro LED unit according to claim 2, wherein the first LED structure, the second LED structure and the third LED structure are embedded in an insulating dielectric.

7. _The multicolor micro LED unit according to claim 6, wherein _the insulating dielectric material is selected from a combination of _Al₂O₃ , _HfO₂ , _Ta₂O₅ , _TiO₂ , _ZrO₂ , _La₂O₃ and _MgO .

8. The multicolor micro LED unit according to claim 6, further comprising:

Microlenses located above the insulating dielectric; and/or

Spacers formed at the bottom of the microlens and at the top of the light emission area.

9. The multicolor micro LED unit according to claim 8, characterized in that:

The lower end of the conductive structure is located on the substrate, but is not electrically connected to the contacts on the substrate; and

The upper end of the conductive structure reaches a position no lower than the top surface of the second or third LED structure; or, the upper end of the conductive structure reaches the top surface of the insulating dielectric or the bottom of the microlens or directly reaches the bottom of the top pad and is electrically connected to the top pad.

10. The multicolor micro LED unit according to claim 8, wherein the microlens comprises a first microlens located above the first LED structure, a second microlens located above the second LED structure, and a third microlens located above the third LED structure, and the first microlens, the second microlens, and the third microlens have different, the same, or partially the same heights.

11. The multicolor micro LED unit according to claim 1, wherein a first reflective layer is provided on the sidewall of the conductive structure.

12. The multicolor micro LED unit according to claim 1, further comprising:

A first bottom reflective layer formed between the first LED structure and the first bonding layer; and/or

A second bottom reflective layer is formed between the second LED structure and the second bonding layer; and/or

A third bottom reflective layer is formed between the third LED structure and the third bonding layer.

13. The multicolor micro LED unit according to claim 11 or 12, wherein the first reflective layer and the bottom reflective layer comprise one or more of a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

14. The multicolor micro LED unit according to claim 13, wherein the DBR layer is a conductive DBR or a dielectric DBR.

15. The multicolor micro LED unit according to claim 11, wherein the first reflective layer is one or more reflective coatings.

16. The multicolor micro LED unit according to claim 1 or 2, wherein the first LED structure, the second LED structure and the third LED structure partially overlap each other.

17. The multicolor micro LED unit according to claim 1 or 2, wherein the cross-sectional shape of the first LED structure, the second LED structure and the third LED structure is rectangular, circular, square, hexagonal or elliptical.

18. The multicolor micro LED unit according to claim 1 or 2, wherein each of the first LED structure, the second LED structure and the third LED structure comprises a first semiconductor epitaxial layer of a first conductivity type, a second semiconductor epitaxial layer of a second conductivity type, and a light-emitting layer located between the first semiconductor epitaxial layer and the second semiconductor epitaxial layer.

19. The multicolor micro LED unit according to claim 1, wherein the plurality of multicolor micro LED pixels are arranged in an N×M pixel array, where N is a positive integer greater than or equal to 1 and M is a positive integer greater than or equal to 2.

20. The multicolor micro LED unit according to claim 1, wherein adjacent multicolor micro LED pixels share one or more LED structures.

21. The multicolor micro LED unit according to claim 2, wherein the plurality of multicolor micro LED pixels includes a first multicolor micro LED pixel and a second multicolor micro LED pixel that share the first LED structure, the second LED structure and/or the third LED structure.

22. The multicolor micro LED unit according to claim 2, characterized in that:

The first LED structure shared by the first multi-color micro LED pixel and the second multi-color micro LED pixel is electrically connected to the first contact of the first LED structure that drives the first multi-color micro LED pixel and the second contact of the first LED structure that drives the second multi-color micro LED pixel.

The second LED structure shared by the first multi-color micro-LED pixel and the second multi-color micro-LED pixel is electrically connected to the third contact of the second LED structure driving the first multi-color micro-LED pixel and the fourth contact of the second LED structure driving the second multi-color micro-LED pixel; and/or

The third LED structure shared by the first multi-color micro-LED pixel and the second multi-color micro-LED pixel is electrically connected to the fifth contact of the third LED structure that drives the first multi-color micro-LED pixel and the sixth contact of the third LED structure that drives the second multi-color micro-LED pixel.

23. A multi-color micro LED pixel array, comprising:

Multiple multi-color micro LED pixels are arranged in an array, and for each row of the array, N multi-color micro LED pixels are arranged in a straight line.

Each multicolor micro LED pixel includes: a first LED structure emitting a first color light, wherein the first LED structure is formed on a substrate; a first metal pillar formed on the substrate; a second LED structure emitting a second color light, wherein the second LED structure is located on the first metal pillar; a second metal pillar formed on the substrate; and a third LED structure emitting a third color light, wherein the third LED structure is located on the second metal pillar;

In a multi-color micro-LED pixel, one of the second LED structure and the third LED structure is shared by the multi-color micro-LED pixel adjacent to the left, and the other of the second LED structure and the third LED structure in a multi-color micro-LED pixel is shared by the multi-color micro-LED pixel adjacent to the right.

Conductive structures located around the plurality of multicolor micro-LED pixels.

24. The multicolor micro LED pixel array according to claim 23, characterized in that: the first LED structure is bonded to the substrate through a first metal bonding layer; and/or

The second LED structure is bonded to the first metal pillar on the substrate via a second metal bonding layer; and/or

25. The multicolor micro LED pixel array according to claim 24, characterized in that:

26. The multicolor micro LED pixel array according to claim 23, characterized in that:

27. The multicolor micro LED pixel array according to claim 23, characterized in that:

The upper end of the conductive structure reaches a position no lower than the top surface of the second or third LED structure; or, the upper end of the conductive structure reaches the top surface of the insulating dielectric surrounding the LED structure or the bottom of the microlens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

28. The multicolor micro LED pixel array according to claim 23, wherein the cross-sectional shape of the first LED structure, the second LED structure and the third LED structure is rectangular, circular, square, hexagonal or elliptical.

29. The multicolor micro LED pixel array according to claim 23, characterized in that:

The second LED structure is electrically connected to two contacts on the substrate, the two contacts on the substrate being used to drive the second LED structure of two adjacent multi-color micro-LED pixels; and

The third LED structure is electrically connected to two contacts on the substrate, which are used to drive the third LED structure of two adjacent multi-color micro LED pixels.

30. The multicolor micro LED pixel array according to claim 23, characterized in that, for each row of the array, the conductive structure comprises:

Along the row direction, the first horizontal portion and the second horizontal portion are located on both sides of the multicolor micro LED pixel;

Multiple first vertical portions arranged between adjacent first LED structures; and

A plurality of second vertical portions are arranged between adjacent second and third LED structures, wherein one end of a first vertical portion is connected to a first horizontal portion, and the other end faces the second or third LED structure but does not contact the second or third LED structure.

One end of the second vertical portion is connected to the second horizontal portion, and the other end faces the first LED structure but does not contact the first LED structure.