Multi-color micro LED pixel with non-coaxial stacked LED structure

Abstract

The present invention describes a multi-color micro LED pixel comprising: a first LED structure emitting light of a first color, where 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 conductive structure surrounding the first LED structure and the second LED structure; the first micro lens is positioned above the first LED structure; and a second microlens over the second LED structure.

Description

Technical Field

[0001] This disclosure generally relates to light-emitting diode (LED) display devices, and more specifically, to multicolor micro LED pixels having a non-coaxial stacked LED structure. Background Technology

[0002] Light-emitting diodes (LEDs) are widely used in lighting, backlighting, and displays. The advantages of using LEDs as pixels include high brightness, low operating voltage, low power consumption, large size, long lifespan, shock resistance, and stable performance. With the development of mini-LED and micro-LED technologies in recent years, consumer devices and applications such as augmented reality (AR), virtual reality (VR), projection, head-up displays (HUDs), mobile device displays, wearable device displays, and automotive displays require LED panels with improved resolution and brightness. For example, an AR display integrated into goggles and positioned close to the wearer's eyes can be as small as a fingernail while still requiring HD resolution (1280×720 pixels) or higher. Many electronic devices require LED panels with specific pixel sizes, pixel spacing, brightness, and viewing angles. Often, achieving maximum resolution and brightness on a small display while maintaining these requirements is challenging. Conversely, in some cases, pixel size and brightness are difficult to balance simultaneously because they have roughly inverse relationships. For example, achieving high brightness per pixel results in low resolution. Similarly, achieving high resolution reduces brightness.

[0003] The light emitted by LED chips is spontaneously emitted, making it non-directional and resulting in a large divergence angle. In micro-LED displays, this large divergence angle causes various problems. Firstly, due to the large divergence angle, only a small portion of the light emitted by the micro-LED can be utilized. This can significantly reduce the efficiency and brightness of the micro-LED display system. Secondly, due to the large divergence angle, the light emitted by one micro-LED pixel may illuminate adjacent pixels, leading to inter-pixel crosstalk, loss of sharpness, and loss of contrast. Figure 1 A conventional solution for reducing large divergence angles is shown, aiming to reduce light waste to lower power consumption and inter-pixel light interference. For example... Figure 1 As shown, the optical isolation structure 110 is located around each micro-LED pixel. However, these individual optical isolation structures occupy a large chip area, increase the manufacturing difficulty, and are not conducive to the miniaturization of micro-LED pixel units.

[0004] Existing multicolor LED designs typically employ a coaxial stacked structure, where LED chips of different colors are stacked together. In this structure, light emitted from the lower LED's emitting region can pass through the upper LED's emitting region and exit from the top, or propagate laterally and exit from the top through side reflection structures. In this coaxially stacked multicolor LED structure, the light emitted from the lower LED's emitting region has a longer propagation path, increasing the probability of light being reflected and absorbed by optical isolation and electrical connection structures, resulting in higher light loss. This can significantly reduce the efficiency and brightness of micro-LED display systems.

[0005] Therefore, there is a need to provide an LED structure for display panels to address the aforementioned drawbacks and other problems. Summary of the Invention

[0006] Improved multicolor LED designs are needed to address the shortcomings of traditional display systems. Specifically, an LED device structure is required that can improve brightness and resolution while effectively maintaining low power consumption.

[0007] The multicolor micro-LED pixels described herein may include a high reflectivity structure to increase the internal reflectivity of the emitted light, while also helping to achieve a narrow beam width, thereby simultaneously improving brightness and resolution and making them suitable for current display panels, particularly for high-definition AR devices and virtual reality (VR) glasses.

[0008] Some exemplary embodiments provide a 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 first LED structure and the second LED structure.

[0009] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: 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 and a conductive structure surrounds the third LED structure.

[0010] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure is bonded to the substrate through a first metal bonding layer; and / or the second LED structure is bonded to a first metal pillar on the substrate through a second metal bonding layer; and / or the third LED structure is bonded to a second metal pillar on the substrate through a third metal bonding layer.

[0011] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the lower end of the first metal pillar is electrically connected to a contact on the substrate, the upper end of the first metal pillar is electrically connected to a 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, the upper end of the second metal pillar is electrically connected to a third metal bonding layer, and is not lower than the top of the second LED structure.

[0012] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned 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 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.

[0013] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

[0014] In some exemplary embodiments of multicolor micro LED pixels, 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. Solid inorganic materials include SiO2, Al2O3, Si3N4, SiCN, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, phosphosilicate glass (PSG), borosilicate glass (BPSG), or any combination thereof. Plastic materials include polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or bonding adhesive microresist BCL-1200, or any combination thereof.

[0015] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a microlens above the insulating dielectric; and / or a spacer formed at the bottom of the microlens and at the top of the light emitting region.

[0016] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 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 microlens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

[0017] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, a first reflective layer is provided on the sidewall of the conductive structure.

[0018] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: 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.

[0019] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer and the bottom reflective layer include one or more of a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

[0020] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the DBR layer is a conductive DBR or a dielectric DBR.

[0021] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer is one or more reflective coatings.

[0022] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure partially overlap each other.

[0023] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the cross-sectional shape of the first LED structure, the second LED structure, and the third LED structure is rectangular or circular.

[0024] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 located therebetween.

[0025] Some exemplary embodiments provide a 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; a first air gap surrounding the first LED structure; a second air gap surrounding the second LED structure; and a conductive structure surrounding the first LED structure and the second LED structure.

[0026] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a second metal pillar formed on a substrate; a third LED structure emitting a third color light, wherein the third LED structure is located on the second metal pillar and a conductive structure surrounds the third LED structure; a third air gap surrounding the third LED structure; and a central electrode located between the first LED structure, the second LED structure and the third LED structure.

[0027] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure is bonded to the substrate through a first metal bonding layer; and / or the second LED structure is bonded to a first metal pillar on the substrate through a second metal bonding layer; and / or the third LED structure is bonded to a second metal pillar on the substrate through a third metal bonding layer.

[0028] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the lower end of the first metal pillar is electrically connected to a contact on the substrate, the upper end of the first metal pillar is electrically connected to a 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, the upper end of the second metal pillar is electrically connected to a third metal bonding layer, and is not lower than the top of the second LED structure.

[0029] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned 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 to the central electrode, 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.

[0030] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first to third air gaps have notches in the outer peripheral portion of the corresponding LED structure adjacent to the central electrode, such that each upper conductive layer of the first LED structure, the second LED structure, and the third LED structure can be electrically connected to the central electrode through the notches.

[0031] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

[0032] In some exemplary embodiments of multicolor micro LED pixels, 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. Solid inorganic materials include SiO2, Al3O3, Si3N4, SiCN, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, phosphosilicate glass (PSG), borosilicate glass (BPSG), or any combination thereof. Plastic materials include polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or bonding adhesive microresist BCL-1200, or any combination thereof.

[0033] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a microlens above an insulating dielectric; and / or a spacer formed at the bottom of the microlens and at the top of the light emitting region.

[0034] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 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 microlens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

[0035] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the lower end of the central electrode is located on the substrate but is not electrically connected to the contacts on the substrate; and the upper end of the central electrode reaches a position not lower than the top surface of the second or third LED structure; preferably, the upper end of the central electrode 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.

[0036] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, a first reflective layer is provided on the sidewall of the conductive structure.

[0037] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: 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.

[0038] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer and the bottom reflective layer include one or more of a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

[0039] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the DBR layer is a conductive DBR or a dielectric DBR.

[0040] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer is one or more reflective coatings.

[0041] In some exemplary embodiments of the multicolor micro light-emitting diode (micro LED) pixel or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure partially overlap each other.

[0042] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the cross-sectional shape of the first LED structure, the second LED structure, and the third LED structure is rectangular or circular.

[0043] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 located therebetween.

[0044] Some exemplary embodiments provide a 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; a conductive structure surrounding the first LED structure and the second LED structure; a first microlens above the first LED structure; and a second microlens above the second LED structure.

[0045] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a second metal pillar formed on the substrate; a third LED structure emitting a third color light, wherein the third LED structure is located on the second metal pillar and a conductive structure surrounds the third LED structure; and a third microlens above the third LED structure.

[0046] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure is bonded to the substrate through a first metal bonding layer; and / or the second LED structure is bonded to a first metal pillar on the substrate through a second metal bonding layer; and / or the third LED structure is bonded to a second metal pillar on the substrate through a third metal bonding layer.

[0047] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the lower end of the first metal pillar is electrically connected to a contact on the substrate, the upper end of the first metal pillar is electrically connected to a 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, the upper end of the second metal pillar is electrically connected to a third metal bonding layer, and is not lower than the top of the second LED structure.

[0048] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned 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 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.

[0049] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

[0050] In some exemplary embodiments of multicolor micro LED pixels, 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. Solid inorganic materials include SiO2, Al2O3, Si3N4, SiCN, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, phosphosilicate glass (PSG), borosilicate glass (BPSG), or any combination thereof. Plastic materials include polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or bonding adhesive microresist BCL-1200, or any combination thereof.

[0051] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a microlens above an insulating dielectric; and / or a spacer formed at the bottom of the microlens and at the top of the light emitting region.

[0052] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 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 microlens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

[0053] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, a first reflective layer is provided on the sidewall of the conductive structure.

[0054] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: 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.

[0055] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer and the bottom reflective layer include one or more of a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

[0056] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the DBR layer is a conductive DBR or a dielectric DBR.

[0057] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer is one or more reflective coatings.

[0058] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure partially overlap each other.

[0059] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the cross-sectional shape of the first LED structure, the second LED structure, and the third LED structure is rectangular or circular.

[0060] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 located therebetween.

[0061] Some embodiments provide a multicolor micro light-emitting diode (micro LED) pixel, comprising: a first LED structure emitting a first color light, the first LED structure being formed on a substrate; a first metal pillar formed on the substrate; a second LED structure emitting a second color light, the second LED structure being located on the first metal pillar; and a conductive structure surrounding the first LED structure and the second LED structure, wherein at least one of the first and second LED structures has an inverted trapezoidal cross-sectional shape.

[0062] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the aforementioned exemplary embodiments, it further includes: a second metal pillar formed on a substrate; and a third LED structure emitting a third color light, the third LED structure being located on the second metal pillar, with a conductive structure surrounding the third LED structure, wherein at least one of the first, second, and third LED structures has an inverted trapezoidal cross-sectional shape.

[0063] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the cross-sectional shape of the first LED structure is an inverted trapezoid, and a first reflective layer is provided on the bottom and sidewalls of the first LED structure; and / or the cross-sectional shape of the second LED structure is an inverted trapezoid, and a second reflective layer is provided on the bottom and sidewalls of the second LED structure; and / or the cross-sectional shape of the third LED structure is an inverted trapezoid, and a third reflective layer is provided on the bottom and sidewalls of the third LED structure.

[0064] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure is bonded to the substrate through a first metal bonding layer; and / or the second LED structure is bonded to a first metal pillar on the substrate through a second metal bonding layer; and / or the third LED structure is bonded to a second metal pillar on the substrate through a third metal bonding layer.

[0065] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the lower end of the first metal pillar is electrically connected to a contact on the substrate, the upper end of the first metal pillar is electrically connected to a 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, the upper end of the second metal pillar is electrically connected to a third metal bonding layer, and is not lower than the top of the second LED structure.

[0066] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned 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 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.

[0067] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

[0068] In some exemplary embodiments of multicolor micro LED pixels, 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. Solid inorganic materials include SiO2, Al2O3, Si3N4, SiCN, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, phosphosilicate glass (PSG), borosilicate glass (BPSG), or any combination thereof. Plastic materials include polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or bonding adhesive microresist BCL-1200, or any combination thereof.

[0069] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: a microlens above an insulating dielectric; and / or a spacer formed at the bottom of the microlens and at the top of the light emitting region.

[0070] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 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 microlens, or directly reaches the bottom of the top pad and is electrically connected to the top pad.

[0071] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, a first reflective layer is provided on the sidewall of the conductive structure.

[0072] In some exemplary embodiments of the multicolor micro LED pixel or any combination of the foregoing exemplary embodiments, it further includes: 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.

[0073] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer and the bottom reflective layer include one or more of a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

[0074] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the DBR layer is a conductive DBR or a dielectric DBR.

[0075] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first reflective layer is one or more reflective coatings.

[0076] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the first LED structure, the second LED structure, and the third LED structure partially overlap each other.

[0077] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, the cross-sectional shape of the first LED structure, the second LED structure, and the third LED structure is rectangular or circular.

[0078] In some exemplary embodiments of multicolor micro LED pixels or any combination of the aforementioned exemplary embodiments, 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 located therebetween.

[0079] Other aspects include components, devices, systems, improvements, methods and processes (including manufacturing methods and applications), and other technologies related to any of the foregoing.

[0080] It should be noted that the various embodiments described above can be combined with any other embodiments described herein. The features and advantages described in the specification are not exhaustive; in particular, many additional features and advantages will be apparent to those skilled in the art from the drawings, specification, and claims. Furthermore, it should be noted that the language used in the specification is chosen primarily for readability and guidance purposes and is not intended to define or limit the subject matter of the invention. Attached Figure Description

[0081] To enable this disclosure to be understood in more detail, a more specific description can be made by referring to the features of various embodiments, some of which are illustrated in the accompanying drawings. However, these drawings only illustrate relevant features of this disclosure and should not be considered limiting, as the description may allow for other valid features.

[0082] Figure 1 This demonstrates a traditional solution for reducing large divergence angles.

[0083] Figure 2 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0084] Figure 3 An embodiment of the present invention is shown. Figure 2 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0085] Figure 4 An embodiment of the present invention is shown. Figure 2 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0086] Figure 5 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0087] Figure 6 An embodiment of the present invention is shown. Figure 5 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0088] Figure 7 An embodiment of the present invention is shown. Figure 5 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0089] Figure 8A A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0090] Figure 8B A top view schematic diagram of a multicolor micro-LED pixel according to another embodiment of the present invention is shown.

[0091] Figure 9 A top view schematic diagram of a multicolor micro LED pixel according to another embodiment of the present invention is shown.

[0092] Figure 10 A top view schematic diagram of a multicolor micro LED pixel according to another embodiment of the present invention is shown.

[0093] Figure 11 A top view schematic diagram of a multicolor micro-LED pixel with a narrow beam width is shown according to an embodiment of the present invention.

[0094] Figure 12 An embodiment of the present invention is shown. Figure 11 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0095] Figure 13 An embodiment of the present invention is shown. Figure 11 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0096] Figure 14 A cross-sectional schematic diagram of the manufacturing process of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0097] Figure 15 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0098] Figure 16 An embodiment of the present invention is shown. Figure 15 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0099] Figure 17 An embodiment of the present invention is shown. Figure 15 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0100] Figure 18 An embodiment of the present invention is shown. Figure 15The diagram shows a cross-sectional view of a multi-color micro LED pixel along the CC line.

[0101] Figure 19 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0102] Figure 20 An embodiment of the present invention is shown. Figure 19 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0103] Figure 21 An embodiment of the present invention is shown. Figure 19 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0104] Figure 22 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0105] Figure 23 An embodiment of the present invention is shown. Figure 22 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA.

[0106] Figure 24 An embodiment of the present invention is shown. Figure 22 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line.

[0107] Figure 25-27 The effect of the distance between the light source and the lens on the LED divergence angle is shown.

[0108] Figure 28-34 A cross-sectional schematic diagram of a multicolor microLED pixel having at least one inverted trapezoidal LED structure is shown according to an embodiment of the present invention.

[0109] Figure 35 A cross-sectional schematic diagram of the manufacturing process of microlenses of different heights according to an embodiment of the present invention is shown.

[0110] By convention, the various features shown in the accompanying drawings may not be drawn to scale. Therefore, for clarity, the dimensions of various features may be arbitrarily enlarged or reduced. Furthermore, some drawings may not depict all parts of a given system, method, or apparatus. Finally, the same reference numerals may be used to denote the same features throughout the specification and drawings. Detailed Implementation

[0111] This document describes numerous details to provide a thorough understanding of the exemplary embodiments illustrated in the accompanying drawings. However, some embodiments may be practiced without many of these specific details, and the scope of the claims is limited only to those features and aspects specifically recited in the claims. Furthermore, well-known processes, components, and materials have not been described exhaustively so as not to unnecessarily obscure relevant aspects of the embodiments described herein.

[0112] In some embodiments, a single multicolor LED pixel comprises two or more LED structures. In some embodiments, each LED structure comprises at least one LED light-emitting layer that emits light of a unique color. When a single multicolor LED pixel contains two LED structures, it is capable of emitting light of two colors and a mixture of those two colors. When a single multicolor LED pixel contains three LED structures, it is capable of emitting light of three colors and a mixture of those three colors.

[0113] Figure 2 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown. Figure 3 An embodiment of the present invention is shown. Figure 2 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA. Figure 4 An embodiment of the present invention is shown. Figure 2 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line. Figure 2-4 As shown, the multi-color 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 each other from the top.

[0114] For convenience, "upward" is used to indicate away from substrate 210, "downward" indicates towards substrate 210, and other directional terms such as top, bottom, above, below, directly below, and under are also interpreted accordingly. The support substrate 210 is a substrate on which an array of various driver circuits are fabricated. In some embodiments, the driver circuits may also be located in a layer above 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, substrate 210 is a Si substrate. In another embodiment, 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 multicolor micro-LED pixels. The circuitry on substrate 210 includes contacts 211 to each individual driver circuit and a ground contact.

[0115] 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 located 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 located between the lower conductive layer 231 and the upper conductive layer 232; 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 located between the lower conductive layer 241 and the upper conductive layer 242. Those skilled in the art should understand 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, and 243 can be light-emitting layers of any color. The descriptions of red, green, and blue light-emitting layers or LED structures herein are merely illustrative and not limiting.

[0116] In some embodiments, 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 located therebetween. The light-emitting layer may be, but is not limited to, a multi-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 layer includes, but is not limited to, InGaN / GaN cycling and InGaP / AlGaInP cycling.

[0117] In some embodiments, the first LED structure 220 may further include an upper connection portion 224 located between the upper conductive layer 222 and the LED light-emitting layer 223, and the upper connection portion is electrically connected to the upper conductive layer 222 and the LED light-emitting layer 223. The upper connection portion 224 is made of metal, including one or more of Al, Au, Rh, Ag, Cr, Ti, Pt, Sn, Cu, AuSn, and TiW.

[0118] In some embodiments, the upper and lower conductive layers can be metal layers or conductive transparent layers, such as ITO, FTO, or copper layers, formed to improve conductivity and transparency. In another embodiment, the lower conductive layer 221 can be a metal layer to form part of the first metal bonding layer 271.

[0119] Although this article uses the term "layer" to describe some features, it should be understood that these features are not limited to a single layer, but may include multiple sub-layers. In some cases, a "structure" can take the form of "layers".

[0120] In some embodiments, such as Figure 2 As shown, 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.

[0121] In some embodiments, the first LED structure 220 is bonded to the substrate 210 via a metal bonding layer 271. The metal bonding layer 271 may be disposed on the substrate 210. In one method, the metal bonding layer 271 is grown on the substrate 210. In some embodiments, contacts 211 on the metal bonding layer 271 and the substrate 210 are electrically connected to the first LED structure 220 located above the metal bonding layer 271, acting as a p-electrode. In some embodiments, the thickness of the metal bonding layer 271 is approximately 0.1 micrometers to 3 micrometers. In a preferred embodiment, the thickness of the metal bonding layer 271 is approximately 0.3 micrometers. 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 at the bottom of the first LED structure 220. The corresponding bonding metal layer is deposited on the substrate 210. In some embodiments, the composition of the metal bonding layer 271 includes Au-Au bonding, Au-Sn bonding, Au-In bonding, Ti-Ti bonding, Cu-Cu bonding, or a combination thereof. For example, if Au-Au bonding is selected, the two Au layers require a Cr coating as an adhesive layer and a Pt coating as an anti-diffusion layer, respectively. The Pt coating is located between the Au layer and the Cr layer. The Cr and Pt layers are located at the top and bottom of the two bonded Au layers. In some embodiments, when the two Au layers are of approximately the same thickness, the Au on the two layers diffuses into each other under high pressure and high temperature, bonding the two layers together. Eutectic bonding, hot-press bonding, and transient liquid phase (TLP) bonding are example techniques that can be used.

[0122] In some embodiments, the metal bonding layer 271 may also serve as a reflector to reflect light emitted from the LED structure above. In some embodiments, the metal bonding layer 271 may include a reflective layer. Furthermore, the reflective layer may include stacked reflective sublayers.

[0123] In some embodiments, such as Figure 4As shown, the second LED structure 230 is bonded to a metal pillar 273 on the substrate 210 via a metal bonding layer 272. The third LED structure 240 is bonded to a metal pillar 275 on the substrate 210 via a metal bonding layer 274. In some embodiments, the lower end of the metal pillar 273 is electrically connected to a contact 211 on the substrate 210, and the upper end of the metal pillar 273 is electrically connected to the metal bonding layer 272, functioning similarly to a P-electrode. In one method, the metal pillar 273 is grown on the substrate 210. In some embodiments, the upper end of the metal pillar 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 pillar 273. In some embodiments, the lower end of the metal pillar 275 is electrically connected to a contact 211 on the substrate 210, and the upper end is electrically connected to the metal bonding layer 274, functioning similarly to a P-electrode. In one method, the metal pillar 275 is grown on the substrate 210. In some embodiments, the upper end of the metal pillar 275 is not lower than the top of the second LED structure 230 so that the third LED structure 240 can be bonded to the metal pillar 275.

[0124] In some embodiments, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are directly bonded together via a metal bonding layer, and metal bonding has lower requirements for surface flatness. Therefore, the multicolor micro LED pixel according to the present invention can combine the advantages of both metal bonding and direct bonding.

[0125] In some embodiments, the first LED structure 220, the second LED structure 230, and the third LED structure 240 are embedded within an insulating dielectric 280. The insulating dielectric 280 is transparent to the light emitted by the first LED structure 220, the second LED structure 230, and the third LED structure 240. In some embodiments, the 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 includes SiO2, Al2O3, Si3N4, SiCN, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, phosphosilicate glass (PSG), borosilicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes polymers such as SU-8, PermiNex, benzocyclobutene (BCB), or transparent plastics (resins) including spin-coated glass (SOG), or bonding adhesive microresist BCL-1200, or any combination thereof. In some embodiments, the insulating dielectric 280 facilitates the passage of light emitted by the LED structure.

[0126] like Figure 2As shown, 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 can be used as a common electrode to connect the upper conductive layer of each LED structure, acting similarly to an N-electrode. That is, the conductive structure 250 can electrically connect the corresponding upper conductive layers 242, 232, and 222 of the LED structure to the negative terminal of an external power source.

[0127] However, those skilled in the art will recognize that the N-electrode and P-electrode of an LED structure are interchangeable. For example, the conductive structure 250 can be used as a common P-electrode to connect the P-type epitaxial layer of each LED structure, while the corresponding N-type epitaxial layer of the LED structure is electrically connected to the metal bonding layer.

[0128] Due to the height difference between the conductive structure and the LED light-emitting layer, the upper conductive layers 242, 232, and 222 can be flat or have upward or downward slopes. For example, when forming the upper conductive layers 242, 232, and 222, if the height of the conductive structure is the same as the height of the LED light-emitting layer, the upper conductive layers 242, 232, and 222 are substantially flat; if the height of the conductive structure is higher than the height of the LED light-emitting layer, the upper conductive layers 242, 232, and 222 include slopes rising from the edge of the LED light-emitting layer toward the conductive structure; if the height of the conductive structure is lower than the height of the LED light-emitting layer, the upper conductive layers 242, 232, and 222 include slopes descending from the edge of the LED light-emitting layer toward the conductive structure. Those skilled in the art should understand that any shape of the upper conductive layer can be designed according to the specific requirements of the micro-LED pixel and falls within the protection scope of this invention.

[0129] In some embodiments, the lower end of the conductive structure 250 may be located on the substrate 210 but not electrically connected to the contacts 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 microlens, or directly reach the bottom of the top pad and be electrically connected to the top pad. In some embodiments, the conductive structure 250 may be used as an optical isolation structure, thus eliminating crosstalk.

[0130] In some embodiments, a microlens 260 is formed on the top surface of an insulating dielectric 280.

[0131] In some embodiments, the microlens 260 can change the outgoing light path of a single micro LED pixel according to design requirements, making the light emitted by the LED device more focused or more diffused.

[0132] In some embodiments, the microlens 260 may be made of various materials that are transparent to light of each wavelength emitted by a single microLED pixel. Exemplary transparent materials for the microlens 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, etc. In some embodiments, the microlens 260 is made of photoresist.

[0133] In some embodiments, the microlens 260 is generally hemispherical in shape.

[0134] It should be understood that a complete display panel comprises an array of many individual pixels and many microlenses. Furthermore, there is no one-to-one correspondence between microlenses and pixel light sources, nor is there a one-to-one correspondence between pixel driver circuitry (not shown) and pixel light sources. Pixel light sources can also be made from multiple separate light elements, such as single-pixel LEDs connected in parallel. In some embodiments, a microlens 260 can cover several lensless individual LED pixels.

[0135] Each microlens 260 has positive optical power and is configured to reduce the divergence or viewing angle of light emitted from the corresponding pixel light source. In one example, the beam emitted from the pixel light source has a fairly wide initial divergence angle. In one embodiment, the initial angle of the edge rays of the beam relative to the vertical axis orthogonal to the substrate 210 is greater than 60 degrees. The light is bent by the microlens 260, such that the new edge rays now have a reduced divergence angle. In one embodiment, the reduced angle is less than 30 degrees. The microlenses in the microlens array are typically identical. Examples of microlenses include spherical microlenses, aspherical microlenses, Fresnel microlenses, and cylindrical microlenses.

[0136] Microlenses 260 typically have a planar side and a curved side. Figure 3 and Figure 4 In this configuration, the bottom of the microlens 260 is flat, and the top is curved. Typical shapes of the base of each microlens 260 include circular, square, rectangular, and hexagonal. Individual microlenses in the microlens array of the display panel may be the same or different in shape, curvature, optical power, size, base, and spacing. In some embodiments, the microlens 260 conforms to the shape of a single LED pixel. 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 differs from the shape of a single LED pixel; for example, the circular base of the microlens has the same width as a single LED pixel but a smaller area because the microlens base is circular, while the base of the single LED pixel is square. In some embodiments, the area of ​​the microlens base is smaller than the area of ​​the pixel light source. In some embodiments, the area of ​​the microlens base is equal to or greater than the area of ​​the pixel light source.

[0137] In some embodiments, brightness enhancement is achieved by integrating a microlens array onto the display panel. In some examples, due to the light-focusing effect of the microlenses, the brightness with a microlens array is four times that without a microlens array in a direction perpendicular to the display surface. In alternative embodiments, the brightness enhancement factor can vary depending on the design of the microlens array and optical spacers. For example, a factor greater than 8 can be achieved.

[0138] Microlenses can be manufactured using various methods, including deposition, patterning, and etching.

[0139] Figure 5 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown. Figure 6 An embodiment of the present invention is shown. Figure 5 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA. Figure 7 An embodiment of the present invention is shown. Figure 5 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line. Figure 5-7 As shown, 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. Figure 5-7 The multi-color micro LED pixels shown are Figure 2-4 The difference shown is that the multi-color micro LED pixels are different in that... Figure 5-7 The multi-color micro LED pixels shown may also include one or more of the following: reflective layer 251, bottom reflective layer 501, bottom reflective layer 502, and bottom reflective layer 503.

[0140] In some embodiments, such as Figure 6 and Figure 7 As shown, a reflective layer 251 is disposed on the sidewall 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 structure toward the conductive structure 250 is reflected by the reflective layer 251 and emitted from the top surface of a single LED pixel.

[0141] In some embodiments, the conductive structure having the reflective layer 251 can be fabricated by a combination of deposition, photolithography, and etching processes. In some embodiments, the conductive structure having the reflective layer 251 can be fabricated by other suitable methods.

[0142] In some embodiments, the reflective layer 253 may be a metal layer with high reflectivity, including one or more metals such as Pt, Rh, Al, Au and Ag, a stacked DBR layer including TiO2 / SiO2 layers, or any other layer with total reflective properties, including a multilayer omnidirectional reflector (ODR), or a combination thereof.

[0143] In some embodiments, the reflective layer 251 may be one or more reflective coatings disposed on the sidewalls of the conductive structure 250. The bottom of each of the one or more reflective coatings does not contact the corresponding LED structure. The one or more reflective coatings may reflect light emitted from the light-emitting area, thereby improving the brightness and luminous efficiency of the micro-LED panel or display. For example, light emitted from the light-emitting area may reach one or more reflective coatings and may be reflected upwards by one or more reflective coatings.

[0144] One or more reflective coatings may be made of highly reflective materials, having a reflectivity greater than 60%, 70%, or 80%, thus reflecting most of the light emitted from the luminescent region. In some embodiments, one or more reflective coatings may comprise one or more metallic conductive materials with high reflectivity. In these embodiments, the one or more metallic conductive materials may comprise one or more of aluminum, gold, or silver. In other embodiments, one or more reflective coatings may be multilayered. More specifically, one or more reflective coatings may comprise one or more stacked reflective material layers and one or more dielectric material layers. For example, one or more reflective coatings may comprise one reflective material layer and one dielectric material layer. In other embodiments, one or more reflective coatings may comprise two reflective material layers and a dielectric material layer located between the two reflective material layers. However, in some other embodiments, one or more reflective coatings may comprise two dielectric material layers and a reflective material layer located between the two dielectric material layers. In some embodiments, the multilayer structure may comprise two or more metal layers, which may comprise one or more of TiAu, CrAl, or TiWAg.

[0145] In some embodiments, one or more reflective coatings may be multilayer omnidirectional reflectors (ODRs), including a metal layer and a transparent conductive oxide (TCO) layer. For example, the multilayer structure may include a dielectric material layer, a metal layer, and a TCO layer. In some embodiments, one or more reflective coatings may include two or more dielectric material layers, alternately arranged to form a distributed Bragg reflector (DBR). For example, one or more reflective coatings may include a dielectric material layer, a metal layer, and a transparent dielectric layer. The transparent dielectric layer may include one or more of SiO2, Si3N4, Al2O3, or TiO2. One or more reflective coatings may also include a dielectric material layer, a TCO, and a DBR. In other embodiments, one or more reflective coatings may include one or more metallic conductive materials with high reflectivity. In these embodiments, the one or more metallic conductive materials may include one or more of aluminum, gold, or silver.

[0146] In some embodiments, the reflective layer 251 may be a conductive reflective layer or a dielectric reflective layer.

[0147] In some embodiments, such as Figure 6 and Figure 7 As shown, bottom reflective layers 501, 502, and 503 are disposed between the metal bonding layer and the LED structure. The material and manufacturing process of the bottom reflective layers are similar to those of reflective layer 251, and will not be described in detail for simplicity. When the bottom reflective layer is a conductive reflective layer, it can be a continuous layer or a discontinuous layer with one or more gaps. When the bottom reflective layer is a dielectric reflective layer, it can be a discontinuous layer with one or more gaps, wherein a conductive material is formed to ensure that the LED structure and the substrate can be electrically connected.

[0148] Figure 8A A top view schematic diagram of a multi-color micro-LED pixel according to an embodiment of the present invention is shown. Figure 8A As shown, the multi-color 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 Figure 8... Figure 2-4 The difference in the multi-color micro-LED pixels shown is 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 structure is that the three LED structures are arranged more closely, which helps to reduce the size of a single multi-color micro-LED pixel.

[0149] Figure 8B A top view schematic diagram of a multicolor micro-LED pixel according to another embodiment of the present invention is shown. Figure 8BAs shown, the multi-color 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. Compared with Figure 8A the multi-color micro-LED pixel shown, the overlapping area between the first LED structure 220, the second LED structure 230, and the third LED structure 240 is increased, which is beneficial to further reducing the size of a single multi-color micro-LED pixel.

[0150] Figure 9 Fig. shows a top view schematic diagram of a multi-color micro-LED pixel according to another embodiment of the present invention. As Figure 9 shown, the multi-color 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. Compared with Figure 8A the multi-color micro-LED pixel shown, Figure 9 the multi-color micro-LED pixel shown only includes two LED structures. In some embodiments, the first LED structure 220 and the second LED structure 230 can be a combination of red-green two colors, red-blue two colors, green-blue two colors, or other two-color combinations.

[0151] Figure 10 Fig. shows a top view schematic diagram of a multi-color micro-LED pixel according to still another embodiment of the present invention. As Figure 10 shown, the multi-color 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.

[0152] However, those skilled in the art should understand that the cross-section of the LED structure can be of any shape.

[0153] Figure 11 Fig. shows a top view schematic diagram of a multi-color micro-LED pixel with a narrow beam width according to an embodiment of the present invention. Figure 12 Fig. shows an embodiment of the present invention Figure 11 cross-sectional schematic diagram of the multi-color micro-LED pixel shown along line AA. Figure 13 Fig. shows an embodiment of the present invention Figure 11 cross-sectional schematic diagram of the multi-color micro-LED pixel shown along line BB. As Figure 11-13 shown, the multi-color 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, a microlens 1160, and a spacer 1170. Figure 11 The multi-color micro-LED pixel shown and Figure 2The difference in the pixels shown is due to the spacer 1170.

[0154] In some embodiments, spacers 1170 are formed at the bottom of the microlens 1160 and at the top of the light emitting region.

[0155] Spacer 1170 is an optically transparent layer formed to maintain the position of microlens 1160 relative to the pixel light source. Spacer 1170 may be made of various materials that are transparent to light of various wavelengths 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, etc. In some embodiments, spacer 1170 is made of photoresist. In some embodiments, spacer 1170 has the same material as microlens 1160. In some embodiments, spacer 1170 and microlens 1160 have different materials.

[0156] In some embodiments, when forming the microlens 1160, the spacer layer 1170 may be formed using the same material as the microlens 1160 in the same process.

[0157] In some embodiments, a reflective layer 1171 is provided on the sidewall of the spacer 1170. The structure, material, 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.

[0158] In some embodiments, the thickness of the spacer 1170, measured from the top surface of the pixel light source, is approximately 2 μm to 10 μm, which helps to achieve a narrow beam width.

[0159] In the above and other embodiments of the present invention, the LED structure is embedded within an insulating dielectric. For conventional SiO2 / SiN insulating dielectrics, H2 from the SiH4 gas precursor passivates pGaN, resulting in high Vf. Therefore, avoiding the use of SiH4-based precursors may be advantageous. 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 includes Al2O3, HfO2, Ta2O5, TiO2, ZrO2, La2O3, MgO, etc.

[0160] Figure 14 A cross-sectional schematic diagram of the manufacturing process of a multicolor micro LED pixel according to an embodiment of the present invention is shown.

[0161] like Figure 14As shown, in step S1, the first LED structure 1420 is formed on the 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.

[0162] In step S2, an insulating dielectric 1480 is filled around and covers the top surface of the first LED structure 1420, and a conductive structure 1450, a first metal pillar 1473, and a second metal pillar 1475 are formed on the substrate 1410, which are flush with the top surface of the insulating dielectric 1480.

[0163] In step S3, a second lower conductive layer 1431 is formed on the second LED light-emitting layer 1433, and the second LED light-emitting layer 1433 is bonded to the first metal pillar 1473.

[0164] 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.

[0165] In step S5, an insulating dielectric 1480 is filled around and covers the top surface of the second LED structure 1430. A conductive structure 1450 and a second metal pillar 1475 flush with the top surface of the insulating dielectric 1480 are formed on the substrate 1410. A third lower conductive layer 1441 is formed on the third LED light-emitting layer 1443. The third LED light-emitting layer 1443 is then bonded to the second metal pillar 1475.

[0166] 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.

[0167] Those skilled in the art should understand that the above method steps are merely examples, and different steps and processes may be used in other embodiments of the present invention.

[0168] Figure 15 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown. Figure 16 An embodiment of the present invention is shown. Figure 15 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA. Figure 17 An embodiment of the present invention is shown. Figure 15The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line. Figure 18 An embodiment of the present invention is shown. Figure 15 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the CC line. Figure 15-18 As shown, the multi-color 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 a microlens 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.

[0169] like Figure 15-18 As shown, the multicolor micro LED pixel also 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 internal reflection occurs at the interface between the air gap and the high-refractive-index material. Therefore, the air gap serves to provide optical isolation and improve light extraction efficiency.

[0170] In some embodiments, the lower ends of air gaps 1525, 1535, and 1545 may reach the substrate 1510, and the upper ends may reach a position not 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 microlens, or directly reach the bottom of the top pad. The cross-sectional shapes of air gaps 1525, 1535, and 1545 are similar to the cross-sectional shapes of the first to third LED structures. That is, if the LED structure is circular, the cross-sections of air gaps 1525, 1535, and 1545 may be circular; if the LED structure is rectangular, the cross-sections of the air gaps may be rectangular. No air gaps are formed on the outer periphery of the LED structure adjacent to the central electrode 1590. That is, each air gap 1525, 1535 and 1545 has a notch in the outer peripheral portion of the LED structure adjacent to the central electrode 1590, so 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 to the central electrode 1590 through the notch.

[0171] In some embodiments, the lower end of the central electrode 1590 may be located on the substrate 1510, but not electrically connected to the contacts on the substrate 1510; the upper end of the central electrode 1590 may reach a position not 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 microlens, or directly reach the bottom of the top pad and be electrically connected to the top pad.

[0172] Figure 19 A top view schematic diagram of a multicolor micro LED pixel according to an embodiment of the present invention is shown. Figure 20 An embodiment of the present invention is shown. Figure 19 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along line AA. Figure 21 An embodiment of the present invention is shown. Figure 19 The diagram shows a cross-sectional view of a multi-color micro-LED pixel along the BB line. Figure 19-21 As shown, the multi-color 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 above the first LED structure 1920, a second microlens 1962 above the second LED structure 1930, and a third microlens 1963 above the third LED structure 1940. The first LED structure 1920, the second LED structure 1930, and the third LED structure 1940 are not coaxially stacked. Instead, they are offset from each other from the top.

[0173] Figure 19-21 The multi-color micro LED pixels shown are Figure 2 The multi-color micro-LED pixels shown are similar, but the difference is that each LED structure has an independent microlens.

[0174] like Figure 19-21 As shown, the cross-sectional shape of the first LED structure 1920, the second LED structure 1930, and the third LED structure 1940 can be rectangular. However, those skilled in the art should understand that the cross-section of the LED structure can be of any shape. For example, as shown... Figure 22-24 As shown, the cross-sectional shape of the first LED structure 2220, the second LED structure 2230 and the third LED structure 2240 can be circular.

[0175] exist Figure 19-24In the illustrated embodiment, each LED structure has an independent microlens, and each microlens can have a different height. Therefore, this is equivalent to each LED structure being located at the top, thereby reducing the chance of light emitted by the lower LEDs being reflected and absorbed by the optical isolation and electrical connection structures, and improving LEE (light extraction efficiency). This structure allows each LED to be designed with appropriate lens size and spacer height to achieve optimal light focusing.

[0176] Figure 25-27 The effect of the distance between the light emitter and the lens on the LED divergence angle is shown. Figure 25 As shown, the light source is located at the focal point, and most of the light that enters the lens exits at an angle approximately parallel to the lens's central axis. For example... Figure 26 As shown, with the light source located inside the focal point, the proportion of light entering the lens increases, but most of the light emanating from the lens exits at an angle deviating from the lens's central axis. For example... Figure 27 As shown, the light source is located outside the focal point, reducing the proportion of light that can enter the lens, but most of the light emitted from the lens is emitted at an angle toward the central axis of the lens.

[0177] In the above embodiments, the cross-sectional shape of each LED structure is trapezoidal, meaning the top area of ​​the LED structure is smaller than the bottom area. However, in other embodiments of the present invention, such as... Figure 28-33 As shown, some LED structures can have an inverted trapezoidal cross-sectional shape, meaning the top area of ​​the LED structure is larger than the bottom area. LED structures with an inverted trapezoidal shape have a higher LEE (light extraction efficiency). Furthermore, reflective layers can be placed on the bottom and sidewalls of the LED structure, which will also improve the LEE.

[0178] like Figure 28 As shown, only the cross-sectional shape of the second LED structure 2820 is an inverted trapezoid, while the cross-sectional shapes of the first LED structure 2810 and the third LED structure 2830 are trapezoidal. The reflective layer 2821 is disposed on the bottom and sidewalls of the second LED structure 2820.

[0179] like Figure 29 As shown, the cross-sectional shape of the second and third LED structures 2920 and 2930 is an inverted trapezoid, while the cross-sectional shape of the first LED structure 2910 is trapezoidal. Two reflective layers 2921 and 2931 are disposed on the bottom and sidewalls of the second and third LED structures 2920 and 2930.

[0180] like Figure 30 As shown, only the cross-sectional shape of the third LED structure 3030 is an inverted trapezoid, while the cross-sectional shapes of the first and second LED structures 3010 and 3020 are trapezoidal. The reflective layer 3031 is disposed on the bottom and sidewalls of the third LED structure 3030.

[0181] like Figure 31 As shown, only the first LED structure 3110 has an inverted trapezoidal cross-sectional shape, while the second LED structure 3120 and the third LED structure 3130 have trapezoidal cross-sectional shapes. The reflective layer 3111 is disposed on the bottom and sidewall of the first LED structure 3110.

[0182] like Figure 32 As shown, the cross-sectional shape of the first and second LED structures 3210 and 3220 is an inverted trapezoid, while the cross-sectional shape of the third LED structure 3230 is trapezoidal. Two reflective layers 3211 and 3221 are disposed on the bottom and sidewalls of the first and second LED structures 3210 and 3220.

[0183] like Figure 33 As shown, the cross-sectional shape of the first to third LED structures 3310, 3320, and 3330 is an inverted trapezoid. Three reflective layers 3311, 3321, and 3331 are disposed on the bottom and sidewalls of the first to third LED structures 3310, 3320, and 3330.

[0184] like Figure 34 As shown, the cross-sectional shapes of the first and third LED structures 3410 and 3430 are inverted trapezoids, while the cross-sectional shape of the second LED structure 3420 is trapezoidal. Two reflective layers 3411 and 3431 are disposed on the bottom and sidewalls of the first and third LED structures 3410 and 3430.

[0185] Figure 35 A cross-sectional schematic diagram of the manufacturing process of microlenses of different heights according to an embodiment of the present invention is shown.

[0186] In step S1, a dielectric layer 3510 is formed on the substrate on which the LED structure and related conductive structure have been fabricated, and a plurality of hemispherical photoresist bumps 3521, 3522, and 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, and 3523 having predetermined dimensions and curvatures can be formed by photolithography, reflow, or imprinting processes.

[0187] In step S2, an etching process is performed to form a plurality of hemispherical bump structures 3511, 3512, and 3513 on the dielectric layer 3510. During the etching process, the etching rate of the dielectric layer 3510 is basically the same as that of the photoresist, so after etching, the shape of the photoresist will be replicated on the dielectric layer 3510.

[0188] In step S3, a photoresist layer of a certain thickness is formed on the hemispherical bump structure 3511 on the dielectric layer 3510. The hemispherical bump structures 3512 and 3513 are not covered by the photoresist layer. In some embodiments of the present invention, the photoresist layer can be of any shape. In embodiments of the present invention, a photoresist layer of a certain thickness can be formed on the entire surface of the dielectric layer 3510 by processes such as spin coating and imprinting, and then the photoresist above the hemispherical bump structures 3512 and 3513 is removed, while the photoresist above the hemispherical bump structure 3511 is retained. An etching process is performed to reduce the height of the hemispherical bump structures 3512 and 3513 by a predetermined distance, and then the residual photoresist on the hemispherical bump structure 3511 is removed.

[0189] In step S4, a photoresist layer of a certain thickness is formed 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 residual photoresist on the hemispherical bump structures 3511 and 3512 is removed.

[0190] In some embodiments, multiple multicolor microLED pixels may share a single conductive structure. For example, Figure 36 shows a top view schematic diagram of four multicolor microLED pixels sharing a single conductive structure according to an embodiment of the present invention.

[0191] As shown in Figure 36, the conductive structure 3650 is a square ring surrounding four multi-color micro-LED pixels 3610, 3620, 3630, and 3640. Each multi-color micro-LED pixel is connected to... Figure 2 The multi-color micro-LED pixels shown are similar, except that the four multi-color micro-LED pixels 3610, 3620, 3630, and 3640 share a common conductive structure 3650. The cross-section of the LED structure in each pixel is circular.

[0192] In some embodiments, the conductive structure 3650 can be used as a common electrode to connect the upper conductive layer of the LED structure in each micro-LED pixel to the negative terminal of an external power supply. In some embodiments, the conductive structure 3650 may also be referred to as a top electrode or an N-electrode.

[0193] In some embodiments, the number of multicolor micro-LED pixels sharing a single conductive structure can be 1×2, 2×2, 2×3, 3×3, etc., to obtain a larger RGB pixel space. In other words, multicolor micro-LED pixels sharing a single conductive structure can be arranged into 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.

[0194] Figure 37 shows a top view schematic diagram of 2×2 multicolor microLED pixels sharing a single conductive structure according to another embodiment of the present invention. The structure shown in Figure 37 is similar to the structure shown in Figure 36; for simplicity, only the differences are described. As shown in Figure 37, the cross-section of the LED structure in each pixel is rectangular, and a microlens 3760 covers 2×2 multicolor microLED pixels.

[0195] Those skilled in the art will understand that microlenses can be arranged in various ways, such as one microlens covering one pixel, as shown in Figure 36; one microlens covering multiple pixels, as shown in Figure 37; or one microlens covering an LED structure, etc.

[0196] In some embodiments, each multicolor microLED pixel may include multiple LED structures, and adjacent multicolor microLED pixels may share one or more LED structures. The LED structure shared by two or more multicolor microLED pixels is electrically connected to multiple contacts on the IC substrate to drive the corresponding LED structure in the two or more multicolor microLED pixels. The LED structure shared by two or more multicolor microLED pixels can be of any color.

[0197] Figure 38 shows a top view schematic diagram of two multi-color micro-LED pixels sharing one LED structure according to an embodiment of the present invention. Figure 39 shows a cross-sectional schematic diagram of the multi-color micro-LED pixel shown in Figure 38 along line AA according to an embodiment of the present invention. Figure 40 shows a cross-sectional schematic diagram of the multi-color micro-LED pixel shown in Figure 38 along line BB according to an embodiment of the present invention. Figure 41 shows a cross-sectional schematic diagram of the multi-color micro-LED pixel shown in Figure 38 along line CC according to an embodiment of the present invention. As shown in Figures 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 circle at the center of each LED structure represents a contact on the IC substrate below the LED structure, and is shown in the 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 the contact 3813 for driving the third LED structure in the first pixel 3810 and the contact 3823 for driving the third LED structure in the second pixel 3820. The third LED structure 3803 is bonded to two metal pillars 3814 and 3824 on the substrate via a metal bonding layer. The lower end of the metal pillar 3814 is electrically connected to the contact 3813 on the substrate, and the upper end of the metal pillar 3814 is electrically connected to the metal bonding layer, serving as the P-electrode of the third LED structure in the first pixel 3810. The lower end of the metal pillar 3824 is electrically connected to the contact 3823 on the substrate, and the upper end of the metal pillar 3824 is electrically connected to the metal bonding layer, serving as the P-electrode of the third LED structure in the second pixel 3820.

[0198] Figure 42 shows a top view schematic diagram of two multi-color micro-LED pixels sharing a single LED structure according to another embodiment of the present invention. The structure shown in Figure 42 is similar to the structure shown in Figure 38, the only difference being that the cross-section of the LED structure in each pixel is rectangular.

[0199] Figure 43 shows a top view schematic diagram of two multi-color micro-LED pixels sharing two LED structures according to an embodiment of the present invention. Figure 44 shows a cross-sectional schematic diagram of the multi-color micro-LED pixel shown in Figure 43 along line AA according to an embodiment of the present invention. Figure 45 shows a cross-sectional schematic diagram of the multi-color micro-LED pixel shown in Figure 43 along line BB according to an embodiment of the present invention. As shown in Figures 43-45, 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 LED structure is shared by the left adjacent pixel, one LED structure is shared by the right adjacent pixel, and one LED structure is not shared by other pixels. The small circle at the center of each LED structure represents a contact on the IC substrate below the LED structure, and is shown in the top view for illustrative purposes only.

[0200] The third LED structure 4303 shared by the first pixel 4310 and the second pixel 4320 is electrically connected to the contact 4313 for driving the third LED structure in the first pixel 4310 and the contact 4323 for driving the third LED structure in the second pixel 4320. The third LED structure 4303 is bonded to two metal pillars 4314 and 4324 on the substrate via a metal bonding layer. The lower end of the metal pillar 4314 is electrically connected to the contact 4313 on the substrate, and the upper end of the metal pillar 4314 is electrically connected to the metal bonding layer, serving as the P-electrode of the third LED structure in the first pixel 4310. The lower end of the metal pillar 4324 is electrically connected to the contact 4323 on the substrate, and the upper end of the metal pillar 4324 is electrically connected to the metal bonding layer, serving as the P-electrode of the third LED structure in the second pixel 4320.

[0201] The second LED structure 4302 shared by the second pixel 4320 and the third pixel 4320 is electrically connected to contacts 4322 for driving the second LED structure in the second pixel 4320 and contacts 4332 for driving the second LED structure in the third pixel 4330. The second LED structure 4302 is bonded to two metal pillars 4325 and 4335 on the substrate via a metal bonding layer. The lower end of the metal pillar 4325 is electrically connected to the contact 4322 on the substrate, and the upper end of the metal pillar 4325 is electrically connected to the metal bonding layer, serving as the P-electrode of the second LED structure in the second pixel 4320. The lower end of the metal pillar 4335 is electrically connected to the contact 4332 on the substrate, and the upper end of the metal pillar 4335 is electrically connected to the metal bonding layer, serving as the P-electrode of the second LED structure in the third pixel 4330.

[0202] In some embodiments, to achieve better light isolation, in a multi-color micro LED pixel array, for each row of pixels, the conductive structure 4350 may include a first horizontal portion 4351 and a second horizontal portion 4352 located on both sides of the pixel along the pixel row direction, a plurality of first vertical portions 4353 arranged between adjacent first LED structures, and a plurality of second vertical portions 4354 arranged 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 but does not contact 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 does not contact the first LED structure.

[0203] Those skilled in the art will understand that a multicolor microLED pixel according to an embodiment of the present invention may comprise any number of LED structures of the same or different colors. For example, a multicolor microLED pixel may comprise four, five, or six LED structures.

[0204] Each dimension of the microLED chip does not exceed 1 centimeter (cm), preferably not exceeding 20 micrometers (μm). The microLED structures are formed in an array within the microLED chip, with resolutions such as 720*480, 640*480, 1920*1080, 1280*720, 2k, or 4k. The diameter of the microLED structures is at the nanometer level, for example, from 20nm to 100nm.

[0205] A microLED chip includes an integrated circuit (IC) backplane and a microLED array. The microLED array comprises multiple microLEDs. Each microLED can form at least a portion of a pixel element on the microLED chip.

[0206] In some embodiments, the IC backplane may be electrically connected to each microLED of the microLED array via separate metal interconnects. In some embodiments, each microLED may be individually electrically controlled by the IC backplane. In some embodiments, the IC backplane may be electrically connected to the electrodes of the microLED chip via metal interconnects. In some embodiments, a dielectric layer may be formed in the gaps between the microLEDs. In some embodiments, a dielectric layer may also be formed in the gaps between interconnects.

[0207] In some embodiments, each microLED in the microLED array may include a micromesa structure. In some embodiments, the micromesa structure may include, from bottom to top, a first type epitaxial layer, a light-emitting layer, and a second type epitaxial layer. That is, of these three layers, the first type epitaxial layer is closest to the IC backplane; the light-emitting layer is located above the first type epitaxial layer and furthest from the IC backplane; and the second type epitaxial layer is located above the light-emitting layer and furthest from the IC backplane. In some embodiments, the light-emitting layer is formed by a plurality of stacked quantum well layers, particularly superlattice stacked quantum well layers. Preferably, the superlattice stacked quantum well layers include multiple 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 multiple semiconductor layers. The main material of the first type epitaxial layer may be, but is not limited to, materials such as Ga, N, As, P, In, or Al. In addition, the first type epitaxial layer may include, from top to bottom, a waveguide layer, a confinement layer, a transition layer, and a window layer; furthermore, an ohmic contact layer may be formed below the window layer. In some embodiments, the second type epitaxial layer is a semiconductor material having a second conductivity type and includes several semiconductor layers. The host material of the second type epitaxial layer may be, but is not limited to, a base material such as Ga, N, As, P, In, or Al. Additionally, the first type epitaxial layer may, from top to bottom, include, but is not limited to, a confinement layer and a waveguide layer; furthermore, in some embodiments, an ohmic contact layer may be, but is not limited to, formed on the confinement layer.

[0208] In some embodiments, a top conductive layer may be formed on the top surface of the microLED array. In some embodiments, this top conductive layer may be shared by all microLEDs in the microLED array. In some embodiments, the light-emitting layer may include at least one quantum well layer. In some embodiments, the microLED array may include a single-layer microLED structure. In some embodiments, the microLED array may include a vertically stacked multilayer microLED structure.

[0209] In some embodiments, the microLED array may include blue microLEDs. In some embodiments, the spacing of the microLED array (i.e., the minimum center-to-center distance between microLEDs) may be from about 2 μm to about 50 μm. In some embodiments, the number of pixels in the microLED chip may be from thousands to millions or more.

[0210] While the detailed description contains many specific details, these should not be construed as limiting the scope of the invention, but are merely illustrative of different examples and aspects of the invention. It should be understood that the scope of the invention includes other embodiments not discussed in detail above. For example, the methods described above can be applied to the integration of non-LED and OLED functional devices with control circuitry that is not pixel-driven. Examples of non-LED devices include vertical-cavity surface-emitting lasers (VCSELs), photodetectors, microelectromechanical systems (MEMS), silicon photonic devices, power electronic devices, and distributed feedback lasers (DFBs). Examples of other control circuitry include current drivers, voltage drivers, transimpedance amplifiers, and logic circuits.

[0211] The foregoing description of the disclosed embodiments is provided to enable making or using the embodiments and variations thereof described herein. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the subject matter disclosed herein. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the following claims and the principles and novel features disclosed herein.

[0212] The features of this invention can 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 / therein, which can be used to program a processing system to perform any of the features proposed herein. The storage medium may include, but is not limited to, high-speed random access memory (such as DRAM, SRAM, DDR RAM, or other random access solid-state storage devices), and may include non-volatile memory (such as one or more disk storage devices, optical disk storage devices, flash memory devices, or other non-volatile solid-state storage devices). The memory may optionally include one or more storage devices remotely located from the CPU. The memory or non-volatile storage devices within the memory include non-transitory computer-readable storage media.

[0213] The features of this invention can be stored on any machine-readable medium and integrated into software and / or firmware for controlling the hardware of a processing system and enabling the processing system to interact with other mechanisms that utilize the results of this invention. Such software or firmware may include, but is not limited to, application code, device drivers, operating systems, and execution environments / containers.

[0214] It should be understood that although this document may use terms such as "first" and "second" to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0215] 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 embodiments and the appended claims, the singular forms “a,” “an,” and “this” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and covers any and all possible combinations of one or more of the listed related items. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0216] As used herein, the term "if" can be interpreted as meaning, depending on the context, that the prerequisite of a statement is true "when..." or "in response to detection". Similarly, the phrases "if it is determined that [the prerequisite of that statement is true]" or "if [the prerequisite of the statement is true]" or "when [the prerequisite of the statement is true]" can be interpreted as meaning, depending on the context, that the stated prerequisite is true "when determined" or "in response to determined" or "according to determined" or "when detected" or "in response to detection".

[0217] For ease of explanation, the above description has been illustrated with reference to specific embodiments. However, the exemplary discussion above is not intended to be exhaustive, nor is it intended to limit the claims to the precise forms disclosed. Many modifications and variations are possible in light of the above teachings. These embodiments were chosen and described in order to best explain the operating principles and practical applications, thereby enabling others skilled in the art to understand them.

Claims

1. A multi-color micro LED pixel, comprising: A first LED structure that emits light of a first color, wherein the first LED structure is formed on a substrate; A first metal pillar formed on the substrate; A second LED structure that emits a second color of light, wherein the second LED structure is located on the first metal pillar; A conductive structure surrounding the first LED structure and the second LED structure; The first microlens is located above the first LED structure; as well as The second microlens is located above the second LED structure.

2. The multi-color micro LED pixel according to claim 1, further comprising: A second metal pillar formed on the substrate; A third LED structure emitting a third color light, wherein the third LED structure is located on the second metal pillar and the conductive structure surrounds the third LED structure; and The third microlens is located above the third LED structure.

3. The multi-color micro LED pixel 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 the first metal pillar on the substrate through 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 multi-color micro LED pixel 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 multi-color micro LED pixel 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 multi-color micro LED pixel according to claim 2, characterized in that, The first LED structure, the second LED structure, and the third LED structure are embedded in an insulating dielectric.

7. The multi-color micro LED pixel according to claim 6, characterized in that, The insulating dielectric material is selected from a combination of Al2O3, HfO2, Ta2O5, TiO2, ZrO2, La2O3 and MgO.

8. The multi-color micro LED pixel according to claim 6, further comprising: Spacers formed at the bottom of the microlens and at the top of the light emission area.

9. The multi-color micro LED pixel 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 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 microlens or directly reaches the bottom of the top pad and is electrically connected to the top pad.

10. The multi-color micro LED pixel according to claim 1, characterized in that, A first reflective layer is provided on the sidewall of the conductive structure.

11. The multi-color micro LED pixel 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.

12. The multicolor micro LED pixel according to claim 10 or 11, characterized in that, The first reflective layer and the bottom reflective layer include one or more of the following: a metal layer, a DBR layer, and a multilayer omnidirectional reflector (ODR).

13. The multi-color micro LED pixel according to claim 12, characterized in that, The DBR layer is a conductive DBR or a dielectric DBR.

14. The multicolor micro LED pixel of claim 10, wherein the first reflective layer is one or more reflective coatings.

15. The multicolor micro LED pixel according to claim 1 or 2, characterized in that, The first LED structure, the second LED structure, and the third LED structure partially overlap each other.

16. The multicolor micro LED pixel according to claim 1 or 2, characterized in that, The cross-sectional shape of the first LED structure, the second LED structure, and the third LED structure is rectangular or circular.

17. The multicolor micro LED pixel according to claim 1 or 2, characterized in that, 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 located between the first semiconductor epitaxial layer and the second semiconductor epitaxial layer.

18. The multicolor Micro-LED pixel according to claim 1 or 2, wherein, The first microlens, the second microlens, and the third microlens have different, the same, or partially the same heights.

Images