Micro LED Structure and Micro LED Panel

Abstract

A micro LED structure and a micro LED panel using the same are disclosed. The disclosed micro LED includes an IC backplane and a stack of mesa structures including at least a first mesa structure and a second mesa structure. The first mesa structure includes a first light-emitting layer, a first connection layer formed on the first light-emitting layer, and a first conductive bonding layer formed below the first light-emitting layer and electrically connecting the first light-emitting layer to the IC backplane. The second mesa structure is formed on the first mesa structure and includes a second light-emitting layer, a second connection layer formed on the second light-emitting layer, a second conductive bonding layer formed below the second light-emitting layer, and a third connection layer formed below the second conductive bonding layer and electrically connected to the second light-emitting layer via the second conductive bonding layer.

Description

[Technical Field]

[0001] The present disclosure relates generally to micro light emitting diode (LED) manufacturing techniques, and more particularly to micro LED structures and micro LED panels using the micro LED structures. [Background technology]

[0002] Inorganic micro light-emitting diodes (LEDs), also known as "microLEDs," are becoming increasingly important due to their use in a variety of applications, including, for example, self-emitting microdisplays, visible light communications, and optogenetics. Compared to conventional organic LED (OLED) or liquid crystal display (LCD)-based microdisplays, microLEDs offer the following advantages: higher wall-plug efficiency, higher brightness, lower efficiency droop, better thermal stability, longer lifetime, faster response speed, higher resolution, higher color gamut, and higher contrast.

[0003] Micro LED panels are manufactured by integrating an array of thousands or millions of micro LEDs with a driver circuit back panel. Each pixel of a micro LED panel is formed by one or more micro LEDs. Micro LED panels can be single-color or multi-color panels. In particular, in the case of multi-color LED panels, each pixel can further include multiple sub-pixels formed by multiple micro LEDs, each corresponding to a different color. For example, three micro LEDs corresponding to red, green, and blue, respectively, can be stacked to form one pixel. Different colors can be mixed to produce a wide range of colors.

[0004] However, existing micro LED technology faces several challenges. For example, one challenge is improving the effective illumination area within each pixel when the distance between adjacent LEDs is determined. Furthermore, once the single LED illumination area is determined, it can be a difficult task to further improve the overall resolution of a micro LED panel because micro LEDs of different colors must occupy designated zones within a single pixel.

[0005] Furthermore, the light emitted by the LED die is generated from spontaneous emission and is therefore not directional, resulting in a large divergence angle. A large divergence angle can cause various problems in micro-LED panels. On the one hand, due to the large divergence angle, only a small portion of the light emitted by the micro-LED can be utilized. This can significantly reduce the efficiency and brightness of the micro-LED display system. On the other hand, due to the large divergence angle, the light emitted by one micro-LED pixel can illuminate its neighboring pixels, resulting in optical crosstalk between pixels, loss of clarity, and loss of contrast. Summary of the Invention

[0006] The present disclosure provides a micro LED structure that addresses problems in the related art, such as those mentioned above. In particular, the disclosed micro LED structure integrates two or more vertically stacked micro LEDs by arranging the micro LED structures in different layers of the micro LED structure and electrically connecting the micro LED structures to an integrated circuit (IC) back panel. The micro LED structure effectively improves the light illumination efficiency within a single pixel area and simultaneously improves the resolution of the micro LED panel.

[0007] Additionally, the disclosed micro LED structure further improves light illumination efficiency by including a reflective layer that not only effectively increases the amount of light emitted by each of the vertically stacked micro LEDs, but also reduces optical crosstalk between the vertically stacked micro LEDs.

[0008] Consistent with the disclosed embodiments, a plurality of the disclosed micro LED structures can be arranged in a micro LED array to form a micro LED panel, with each of the plurality of micro LED structures corresponding to a pixel of the disclosed micro LED structure and with multiple vertically stacked micro LEDs within a pixel corresponding to multiple sub-pixels, respectively.

[0009] In some embodiments, the disclosed micro LED structure comprises an IC backplane, a stack of mesa structures including a first mesa structure and a second mesa structure, and a dielectric layer between the first mesa structure and the second mesa structure.

[0010] In some embodiments, the first mesa structure is on an IC backplane and can include a first light emitting layer, a first top connecting layer formed on the first light emitting layer and electrically connected to the first light emitting layer, and a conductive bonding layer formed below the first light emitting layer and electrically connecting the first light emitting layer to the IC backplane.

[0011] In some embodiments, the second mesa structure is on the first mesa structure and can include a second light emitting layer, a second top connection layer formed on the second light emitting layer and electrically connected to the second light emitting layer, a second conductive bonding layer formed below the second light emitting layer, and a second bottom connection layer formed below the second conductive bonding layer and electrically connected to the second light emitting layer via the second conductive bonding layer.

[0012] In some embodiments, the second mesa structure can further include a second bottom connection layer formed on the bottom of the conductive bonding layer and electrically connected to the top of it. In some embodiments, the first mesa structure can have no second connection layer, in that the first conductive bonding layer can bond the first light-emitting layer to an IC backplane.

[0013] In some embodiments, a third mesa structure may be stacked on top of the second mesa structure. The third mesa structure may comprise the same layers as the second mesa structure. In some embodiments, a dielectric layer may be formed between the second mesa structure and the third mesa structure.

[0014] The dielectric layer formed between the first connecting layer and the second connecting layer of the micro LED panel herein can then be applied to a micro LED display, a micro projector, etc.

[0015] In some embodiments, each of the light emitting layers comprises a P-type semiconductor layer, an N-type semiconductor layer, and a quantum well layer between the P-type and N-type semiconductor layers. For example, each of the light emitting layers may comprise a P-type semiconductor layer at the bottom and an N-type semiconductor layer at the top, thereby forming a PN junction, or each of the light emitting layers may comprise an N-type semiconductor layer at the bottom and a P-type semiconductor layer at the top, thereby forming an NP junction. [Brief explanation of the drawings]

[0016] [Figure 1] 1A-1C are cross-sectional views of micro LED structures according to some embodiments of the present disclosure. [Figure 2] 1 is a cross-sectional view of another micro LED structure according to some embodiments of the present disclosure. [Figure 3] 1 is a cross-sectional view of another micro LED structure according to some embodiments of the present disclosure. [Figure 4] 1 is a cross-sectional view of another micro LED structure according to some embodiments of the present disclosure. [Figure 5] FIG. 1 illustrates a top view of an exemplary micro LED structure according to some embodiments of the present disclosure. [Figure 6] FIG. 1B is a top view of another exemplary micro LED structure according to some embodiments of the present disclosure. [Figure 7] FIG. 1 is a top view of an exemplary micro-LED panel, according to some embodiments of the present disclosure. [Figure 8]FIG. 1 is a top view of another exemplary micro-LED panel, according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] To provide a further understanding of the present disclosure, reference will now be made in detail to exemplary embodiments. The specific embodiments described and the accompanying drawings are merely illustrative of specific ways to make and use the disclosure and do not limit the scope of the disclosure or the appended claims.

[0018]

[0013] Figure 1 is a cross-sectional view of a micro LED structure 10 according to some embodiments of the present disclosure. As shown in Figure 1, the micro LED structure 10 includes an IC backplane 900 and three mesa structures. Specifically, of the three mesa structures, a first mesa structure includes, from bottom to top, a first conductive bonding layer 103, a first light emitting layer 100 (e.g., a layer that emits red light), and a first top connection layer 101. The first top connection layer 101 is electrically connected to the top of the first light emitting layer 100, and the first conductive bonding layer 103 bonds the bottom of the first light emitting layer 100 to the IC backplane 900. A second mesa structure of the micro LED structure 10 includes, from bottom to top, a second bottom connection layer 202, a second conductive bonding layer 203, a second light emitting layer 200 (e.g., a layer that emits green light), and a second top connection layer 201. The second top connection layer 201 is electrically connected to the top of the second light emitting layer 200, and the second bottom connection layer 202 electrically connects the bottom of the second light emitting layer 200 to the IC backplane 900. The third mesa structure of the micro LED structure 10 comprises, from bottom to top, a third bottom connection layer 302, a third conductive bonding layer 303, a third light emitting layer 300 (e.g., a layer that emits blue light), and a third top connection layer 301. The third top connection layer 301 is electrically connected to the top of the third light emitting layer 300, and the third bottom connection layer 302 electrically connects the bottom of the third light emitting layer 300 to the IC backplane 900. The three mesa structures are stacked on the IC backplane 900, with the second mesa structure formed above the first mesa structure and the third mesa structure formed above the second mesa structure. Contact pads (e.g., 901, 902, 903) may be present on the IC backplane 900, each of which provides an electrical signal to the first, second, or third mesa structure, respectively. While FIG. 1 shows the micro LED structure 10 having three mesa structures, micro LED structures consistent with the present disclosure are not limited to a particular number of vertically stacked mesa structures. For example, other exemplary micro LED structures may have a stack of two mesa structures or a stack of four mesa structures formed on an IC backplane.

[0019] 1 , in some embodiments, a dielectric material 700 may be filled between the top connection layer 101, 201 and the bottom connection layer 202, 302. For example, the dielectric material 700 may form a first dielectric layer 701 between the first top connection layer 101 and the second bottom connection layer 202, and a second dielectric layer 702 between the second top connection layer 201 and the third bottom connection layer 302. In some embodiments, the dielectric material 700 may fill gaps in the micro LED structure 10, thereby preventing the light emitting layers (e.g., light emitting layers 100, 200, 300) from being electrically connected to one another.

[0020] In some embodiments, light-emitting layers 100, 200, and 300 can emit light of different colors or light images. In some exemplary embodiments, first light-emitting layer 100 is selected as a red light-emitting layer, second light-emitting layer 200 is selected as a green light-emitting layer, and third light-emitting layer 300 is selected as a blue light-emitting layer. The above color assignments are for illustrative purposes only. Consistent with the disclosed embodiments, other combinations of light colors can be assigned to the light-emitting layers to achieve any desired result.

[0021] When the mesa structures of the micro LED structure 10 are projected perpendicularly onto a horizontal plane, each mesa structure forms a projected area on the horizontal plane. Each projected area on the horizontal plane has a contour, which is referred to herein as a projected contour in a plan view (i.e., top view). In some embodiments, the disclosed micro LED structure is configured such that the projected contour of the upper light-emitting layer in the plan view is disposed within the projected shape of the lower light-emitting layer in the plan view, thereby forming multiple mesa structures with different widths. Specifically, FIG. 5 is a top view of the micro LED structure 10 of FIG. 1. As shown in FIG. 5, R, G, and B represent the areas of the light-emitting layers 100, 200, and 300 formed in the top view, respectively. In this exemplary embodiment, the projected contour of the light-emitting layer 300 is disposed within the projected contour of the light-emitting layer 200, and the projected contour of the light-emitting layer 200 is disposed within the contour of the light-emitting layer 100.

[0022] 1 , in the exemplary embodiment shown therein, the sidewalls of conductive bonding layers 103, 203, and 303 are aligned with the sidewalls of light-emitting layers 100, 200, and 300, respectively. Specifically, the sidewalls of conductive bonding layer 103 are aligned with the sidewalls of light-emitting layer 100, the sidewalls of conductive bonding layer 203 are aligned with the sidewalls of light-emitting layer 200, and the sidewalls of conductive bonding layer 303 are aligned with the sidewalls of light-emitting layer 300.

[0023] In some embodiments, the conductive bonding layer may be transparent or non-transparent. In some embodiments, the material of the conductive bonding layer is selected from one of metal, composite metal, or transparent conductive material. In some embodiments, the transparent conductive material may be made of transparent plastic (resin) or silicon dioxide (SiO2), such as spin-on glass (SOG), adhesive Micro Resist BCL-1200, or the like. The metal may be selected from copper (Cu), gold (Au), or the like. In some embodiments, the thickness of the conductive bonding layer (e.g., 103, 203, 303) may be in the range of about 0.1 micron to about 5 microns. In some embodiments, the metal composition of the bonding layer may include Au-Au bonding, Au-Sn bonding, Au-In bonding, Ti-Ti bonding, Cu-Cu bonding, or a combination thereof. For example, if an Au-Au bond is required, two layers of Au each require a chromium (Cr) coating as an adhesion layer and a platinum (Pt) coating between the gold layer and the chromium coating as a diffusion barrier layer. A Cr layer and a Pt layer may be formed on both Au layers to be bonded. In some embodiments, when the thicknesses of the two Au layers to be bonded are approximately the same, interdiffusion of Au on both Au layers can bond the two layers together under high pressure and high temperature. Exemplary bonding techniques may include eutectic bonding, thermocompression bonding, and transient liquid phase bonding (TLP).

[0024] In some embodiments, the material of the first connecting layer 101, 201, 301 and the second connecting layer 202, 302 may be selected from a transparent conductive material. In some embodiments, the transparent conductive material may be indium tin oxide (ITO). In some embodiments, the thickness of the ITO layer may be in the range of about 0.01 micron to about 1 micron.

[0025] In some embodiments, a through-common connection layer via 400 filled with a conductive metal may be formed next to the light emitting layers 100, 200, 300 and next to the stack of mesa structures. In some exemplary embodiments, the through-common connection layer via 400 is electrically connected to the light emitting layers 100, 200, 300 via the top connection layers 101, 201, 301, respectively, as shown in FIG. 1 . In some embodiments, a top contact pad 401 may be formed on top of the through-common connection layer via 400. The top contact pad 401 may be electrically connected to circuitry external to the micro LED structure 10.

[0026] In some embodiments, at least one of the through-anode connection layer vias 500, 600 may be formed adjacent to the stacked mesa structure of the micro LED structure 10. The through-anode connection layer vias 500, 600 are formed at a location separate from the location of the through-common connection layer via 400. For example, the through-anode connection layer vias 500, 600 may be located on a different side of the mesa structure from the through-common connection layer via 400. The through-vias 400, 500, 600 are not electrically connected to each other.

[0027] 1 , through-anode connection layer via 500 connects light-emitting layer 200 to IC backplane 900 through bottom connection layer 202. Through-anode connection layer via 600 connects light-emitting layer 300 to IC backplane 900 through bottom connection layer 302. In this exemplary embodiment, first light-emitting layer 100 is electrically connected to IC backplane 900 through conductive bonding layer 103, and therefore no through-connection layer via is required to connect first light-emitting layer 100 to IC backplane 900.

[0028] FIG. 5 schematically illustrates a top view of the micro LED structure 10 of FIG. 1 according to an exemplary embodiment. The dotted rectangles represent the bottom connection layers 202 and 302, respectively. Other layers are not shown in FIG. 5 to better illustrate the relevant structural features. As shown in FIG. 5, the top contact pad 401 is formed on the opposite side of the mesa structure from the through-anode connection layer vias 500, 600. The through-anode connection layer vias 500, 600 are formed in a direction perpendicular to the adjacent edges of the mesa structure.

[0029]

[0031] Figure 6 schematically illustrates a top view of the micro LED structure 10 of Figure 1 according to another exemplary embodiment. As shown in Figure 6, through-anode connection layer vias 500, 600 are formed in a direction parallel to adjacent edges of the mesa structure. The embodiments of Figures 5 and 6 are for illustrative purposes only. The through-common connection layer vias and the through-anode connection layer vias can be formed at any location within the micro LED area.

[0030] 7 is a top view of a micro LED panel 11 according to an exemplary embodiment. As shown in FIG. 7, the micro LED panel 11 includes an array of micro LED structures 10. As shown in FIG. 7, the top contact pads 401 of the multiple micro LED structures 10 in each row are connected to each other to form a continuous line. A shared contact pad 402 connects all the rows of the top contact pads 401 to each other. In this exemplary embodiment, the distribution direction of the through-anode connection layer vias 500, 600 is perpendicular to the distribution direction of the top contact pads 401.

[0031] 8 is a top view of a micro LED panel 11 according to another exemplary embodiment. As shown in FIG. 8, adjacent rows of micro LEDs share a single top contact pad 401. This arrangement allows for a higher integration density of the micro LED panel.

[0032] In some embodiments, each mesa structure can further include a reflective layer. The reflective layer in each mesa structure can be formed on the bottom surface of the respective light-emitting layer or on the bottom surface of the respective conductive bonding layer. Furthermore, a reflective layer can be formed between mesa structures, for example, between the bottom connection layer of a higher mesa structure and the top connection layer of a lower mesa structure. These embodiments are described in detail below with reference to Figures 2-4.

[0033] FIG. 2 is a cross-sectional view of a micro LED structure 20 according to some exemplary embodiments. The micro LED structure 20 is a variation of the micro LED structure 10 (FIG. 1). Like numbers in FIGS. 1 and 3 refer to like structures, and details thereof will not be repeated herein. Only the differences between FIGS. 1 and 2 are described below. As shown in FIG. 2, at least one mesa structure may have a reflective layer (e.g., 104, 204, 304) formed on the bottom surface of its light-emitting layer (e.g., 100, 200, 300). For example, reflective layers 104, 204, 304 are formed on the bottom surfaces of the light-emitting layers 100, 200, 300, respectively. The sidewalls of the reflective layers 104, 204, 304 are aligned with the sidewalls of the light-emitting layers 100, 200, 300 of the mesa structure, respectively. For example, in a bottom mesa structure, the reflective layer 104 is formed on the bottom surface of the light emitting layer 100, and the sidewalls of the reflective layer 104 are aligned with the sidewalls of the light emitting layer 100; in a middle mesa structure, the reflective layer 204 is formed on the bottom surface of the light emitting layer 200, and the sidewalls of the reflective layer 204 are aligned with the sidewalls of the light emitting layer 200; and in a top mesa structure, the reflective layer 304 is formed on the bottom surface of the light emitting layer 300, and the sidewalls of the reflective layer 304 are aligned with the sidewalls of the light emitting layer 300. In some embodiments, the reflective layer of the micro LED structure 20 comprises a stacked transparent layer and a metal omnidirectional reflector (ODR) layer, a stacked distributed Bragg reflector (DBR) layer, or a high reflectivity metal. In some embodiments, the thickness of the reflective layer is in the range of about 0.1 micron to about 5 microns.

[0034] FIG. 3 is a cross-sectional view of a micro LED structure 30 according to some example embodiments. The micro LED structure 30 is a variation of the micro LED structure 10 (FIG. 1). Like numbers in FIGS. 1 and 3 refer to like structures, the details of which will not be repeated herein. Only the differences between FIGS. 1 and 3 will be described below. As shown in FIG. 3, reflective layers 105, 205, and 305 are formed on the bottom surfaces of the conductive bonding layers 103, 203, and 303, respectively. Similarly, the sidewalls of the reflective layers 105, 205, and 305 are aligned with the sidewalls of the conductive bonding layers 103, 203, and 303, respectively, of the mesa structure. For example, in the bottom mesa structure, the reflective layer 105 is formed on the bottom surface of the conductive bonding layer 103, and the sidewalls of the conductive bonding layer 103 are aligned with the sidewalls of the corresponding reflective layer 105; in the middle mesa structure, the reflective layer 205 is formed on the bottom surface of the conductive bonding layer 203, and the sidewalls of the conductive bonding layer 203 are aligned with the sidewalls of the corresponding reflective layer 205; and in the top mesa structure, the reflective layer 305 is formed on the bottom surface of the conductive bonding layer 303, and the sidewalls of the conductive bonding layer 303 are aligned with the sidewalls of the corresponding reflective layer 305. In some embodiments, each of the reflective layers of the micro LED structure 30 comprises a stacked transparent layer and a metal ODR layer, a stacked DBR layer, or a high-reflectivity metal.

[0035] FIG. 4 is a cross-sectional view of a micro LED structure 40 according to some embodiments of the present disclosure. The micro LED structure 40 is a variation of the micro LED structure 10 (FIG. 1). Compared with FIG. 1, like numbers in FIG. 4 refer to like structures, and details thereof will not be repeated herein. Only differences from FIG. 4 are described below. As shown in FIG. 4, a transmissive-reflective layer (e.g., 206 or 306) is formed between two vertically adjacent mesa structures, for example, between the top connecting layer of the lower mesa structure and the bottom connecting layer of the upper mesa structure. In this exemplary embodiment, the sidewalls of the transmissive-reflective layers 206, 306 may be aligned with the sidewalls of the light-emitting layers (e.g., 200, 300, respectively) of the respective upper mesa structures. That is, the transmissive-reflective layer 206 is formed on the first top connection layer 101 of the intermediate mesa structure and on the bottom of the second bottom connection layer 202, and the sidewalls of the transmissive-reflective layer 206 are aligned with the sidewalls of the light-emitting layer 200 of the intermediate mesa structure. The transmissive-reflective layer 306 is formed on the second top connection layer 201 of the upper mesa structure and on the bottom of the third bottom connection layer 302, and the sidewalls of the transmissive-reflective layer 306 are aligned with the sidewalls of the light-emitting layer 300 of the upper mesa structure. The transmissive-reflective layers 206 and 306 reflect light emitted from their respective lower light-emitting layers (e.g., 100 and 200, respectively). For example, upward light (e.g., red light) emitted from the light-emitting layer 100 is reflected outward from the side surface of the transmissive-reflective layer 206 by the transmissive-reflective layer 206. Similarly, upward light (eg, green light) emitted from light-emitting layer 200 is reflected outward from the side surface of transflective layer 303 by transflective layer 306 .

[0036] In some embodiments, each of the above-mentioned reflective layers may include a distributed Bragg reflector (DBR) structure. For example, the reflective layer may be formed by stacking multiple layers of alternating or dissimilar materials with varying refractive indices. In some embodiments, each layer boundary in the DBR structure may cause partial reflection of light waves. In some embodiments, the reflective layer is made of multiple layers of SiO2 and Ti3O5. In some embodiments, the reflective layer is made of multiple layers of Au and / or indium tin oxide (ITO). By manipulating the thickness and / or number of the SiO2 and Ti3O5 layers or the thickness and / or number of the Au and / or ITO layers, selective reflection or transmission of specific wavelengths of light may be achieved. For example, in an exemplary design, the reflective layer 206 in FIG. 4 reflects red light, and the reflective layer 306 in FIG. 4 reflects green light. For example, the DBR structure shown in Table 1 below may be used for the reflective layer that reflects green light from a green light-emitting layer. TIFF2025539960000002.tif108170

[0037] In some embodiments, the reflective layer 304 of the green light LED structure may have low absorption (e.g., 5% or less) of the light generated by the different layers of the three-color LED device. In some embodiments, the reflective layer 304 of the green light layer has high reflectivity (e.g., 95% or more) of the light generated thereon, e.g., green and blue light.

[0038] In some exemplary embodiments, the first light-emitting layer 100 of the micro LED structure 10 (FIG. 1), 20 (FIG. 2), 30 (FIG. 3), or 40 (FIG. 4) is designed to emit red light. Examples of red light-emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some embodiments, the films in the red light-emitting layer may include layers of P-type GaP / P-type InGaN light-emitting layer / InGaN / N-type InGaN / N-type GaAs. In some embodiments, the P-type may be Mg-doped and the N-type may be Si-doped. In some embodiments, the thickness of the light-emitting layer 100 may be in the range of about 0.3 microns to about 5 microns.

[0039] In some embodiments, the second light-emitting layer 200 of the micro LED structure 10 (FIG. 1), 20 (FIG. 2), 30 (FIG. 3), or 40 (FIG. 4) is designed to emit green light. Examples of green light-emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some embodiments, the films in the green light-emitting layer 200 may include a P-type GaN / InGaN light-emitting layer / N-type GaN layer. In some embodiments, the P-type may be Mg-doped, and the N-type may be Si-doped. In some embodiments, the thickness of the light-emitting layer 200 may be in the range of about 0.3 microns to about 5 microns.

[0040] In some embodiments, the light emitting layer 300 of the micro LED structure 10 (FIG. 1), 20 (FIG. 2), 30 (FIG. 3), or 40 (FIG. 4) is designed to emit blue light. Examples of blue light emitting layers include III-V nitride, III-V arsenide, III-V phosphide, and III-V antimonide epitaxial structures. In some embodiments, the films in the blue light emitting layer 300 may include a P-type GaN / InGaN light emitting layer / N-type GaN layer. In some embodiments, the P-type may be Mg-doped, and the N-type may be Si-doped. In some embodiments, the thickness of the blue light emitting layer 300 may be in the range of about 0.3 microns to about 5 microns.

[0041] In some embodiments, in micro LED structure 10 (FIG. 1), 20 (FIG. 2), 30 (FIG. 3), or 40 (FIG. 4), the top connection layer of the micro LED structure (e.g., third top connection layer 302) is deposited on the light emitting layer 300. In some embodiments, the thickness of the third top connection layer 302 (ITO layer) can be from about 0.01 micron to about 1 micron.

[0042] In some embodiments, the microlens 800 may be formed on top of a micro LED structure (eg, the micro LED structure shown in Figures 1-4).

[0043] The micro LEDs described in the disclosed embodiments have a very small volume. The micro LEDs may be organic or inorganic LEDs. In some embodiments, the micro LEDs may be applied to a micro LED array panel. The light-emitting area of ​​the micro LED array panel may be very small, e.g., 1 mm x 1 mm, 3 mm x 5 mm, etc. In some embodiments, the light-emitting area may be the area of ​​the micro LED array within the micro LED array panel. The micro LED array panel may include one or more micro LED arrays forming a pixel array, e.g., a 1600 x 1200, 680 x 480, or 1920 x 1080 pixel array, in which the micro LEDs are pixels. The diameter of the micro LEDs may be in the range of approximately 200 nm to 2 μm. In some embodiments, an IC backplane may be formed on the backside of the micro LED array and electrically connected to the micro LED array. In some embodiments, the IC backplane may receive signals, such as image data, from an external device via signal lines to control the on / off (e.g., whether to emit light) of the corresponding micro LEDs.

[0044] Thus, different types of display panels can be fabricated. For example, in some embodiments, the resolution of the display panel can range from 8x8 to 3840x2160. Common display resolutions include QVGA, which has a 320x240 resolution and a 4:3 aspect ratio; XGA, which has a 1024x768 resolution and a 4:3 aspect ratio; D, which has a 1280x720 resolution and a 16:9 aspect ratio; FHD, which has a 1920x1080 resolution and a 16:9 aspect ratio; UHD, which has a 3840x2160 resolution and a 16:9 aspect ratio; and 4K, which has a 4096x2160 resolution and a 1.9 aspect ratio. A wide variety of pixel sizes can also exist, ranging from submicron to 10mm or larger. The size of the overall display area can also vary greatly, ranging from small diagonals of tens of microns or less to hundreds of inches or more.

[0045] It will be understood by those skilled in the art that the micro LED display panel is not limited by the above structure and may include more or fewer components than those shown, or some components may be combined, or different components may be utilized.

[0046] It should be noted that relational terms such as "first" and "second" are used herein only to distinguish one entity or operation from another and do not require or imply an actual relationship or order between those entities or operations. Furthermore, the words "comprising," "having," "containing," and "including," as well as other similar forms, are intended to be equivalent in meaning and open-ended in that the one or more items following any one of these words are not intended to be an exhaustive listing of such one or more items, nor are they intended to be limited to only the listed one or more items.

[0047] As used herein, unless otherwise stated, the term "or" encompasses all possible combinations unless impracticable. For example, if it is stated that a database can include A or B, then the database can include A, or B, or A and B, unless otherwise stated or impracticable. As a second example, if it is stated that a database can include A, B, or C, then the database can include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C, unless otherwise stated or impracticable.

[0048] It is understood by those skilled in the art that all or part of the steps for implementing the above-mentioned embodiments may be implemented by hardware, or may be implemented by a program instructing related hardware. The program may be stored in the above-mentioned flash memory, the above-mentioned conventional computer device, the above-mentioned central processing module, the above-mentioned adjustment module, etc.

[0049] The above description is only an embodiment of the present disclosure, and the present disclosure is not limited thereto. Any modifications, equivalent replacements and improvements made without departing from the concept and principle of the present disclosure shall fall within the protection scope of the present disclosure.

Claims

1. an integrated circuit (IC) backplane; a stack of mesa structures, the stack comprising a first mesa structure on the IC backplane and a second mesa structure on the first mesa structure; a dielectric layer between the first mesa structure and the second mesa structure; Equipped with The first mesa structure comprises: a first light-emitting layer; and a first connection layer formed on the first light-emitting layer and electrically connected to the first light-emitting layer; a first conductive bonding layer formed under the first light-emitting layer, electrically connecting the first light-emitting layer to the IC backplane; Equipped with The second mesa structure comprises: a second light-emitting layer; and a second connection layer formed on the second light-emitting layer and electrically connected to the second light-emitting layer; a second conductive adhesive layer formed under the second light-emitting layer; a third connection layer formed under the second conductive bonding layer and electrically connected to the second light-emitting layer via the second conductive bonding layer; A micro light emitting diode (LED) structure comprising:

2. 10. The micro LED structure of claim 1, wherein, in plan view, an outline of the second mesa structure is disposed within an outline of the first mesa structure.

3. 3. The micro LED structure of claim 2, wherein sidewalls of the first and second conductive bonding layers are aligned with sidewalls of the first and second light emitting layers, respectively.

4. 4. The micro LED structure of claim 3, further comprising a transflective layer formed between the first and third connecting layers.

5. 5. The micro LED structure of claim 4, wherein a sidewall of the transflective layer is aligned with a sidewall of the adjacent second conductive bonding layer.

6. 5. The micro LED structure of claim 4, wherein the transflective layer comprises a stack of distributed Bragg reflector (DBR) layers.

7. 3. The micro LED structure of claim 2, wherein at least one of the first mesa structure and the second mesa structure further comprises a reflective layer formed on a bottom surface of the first light emitting layer or the second light emitting layer, the reflective layer having sidewalls aligned with sidewalls of the first light emitting layer or the second light emitting layer.

8. The reflective layer is a laminated transparent layer and a metallic omnidirectional reflective (ODR) layer; a stacked distributed Bragg reflector (DBR) layer, or high reflectivity metal 8. The micro LED structure of claim 7, comprising:

9. 3. The micro LED structure of claim 2, wherein at least one of the first mesa structure and the second mesa structure further comprises a reflective layer formed on a bottom surface of the first conductive bonding layer or the second conductive bonding layer, wherein sidewalls of the reflective layer are aligned with sidewalls of the first conductive bonding layer or the second conductive bonding layer.

10. The reflective layer is a laminated transparent layer and a metallic omnidirectional reflective (ODR) layer; a stacked distributed Bragg reflector (DBR) layer, or high reflectivity metal 10. The micro LED structure of claim 9, comprising:

11. 10. The micro LED structure of claim 1, wherein the first conductive bonding layer and the second conductive bonding layer each comprise a metal, a composite metal, or a transparent conductive material.

12. The transparent conductive material is SiO ２ or ITO.

13. 10. The micro LED structure of claim 1, wherein the first connecting layer, the second connecting layer, and the third connecting layer each comprise a transparent conductive material.

14. 14. The micro LED structure of claim 13, wherein the transparent conductive material is indium tin oxide (ITO).

15. 10. The micro LED structure of claim 1, further comprising a first through via formed adjacent to the stack of mesa structures, the first through via being connected to the first light emitting layer through the first connecting layer and to the second light emitting layer through the second connecting layer.

16. 16. The micro LED structure of claim 15, further comprising a second through via formed adjacent the second mesa structure, the second through via electrically connecting the third connection layer to the IC backplane.

17. 10. The micro LED structure of claim 1, wherein the first light emitting layer and the second light emitting layer each comprise a P-type semiconductor layer and an N-type semiconductor layer, the P-type semiconductor layer and the N-type semiconductor layer forming a PN junction.

18. 20. The micro LED structure of claim 17, wherein the first light emitting layer and the second light emitting layer each further comprise a quantum well layer formed between the P-type semiconductor layer and the N-type semiconductor layer.

19. the stack of mesa structures further comprising a third mesa structure formed on the second mesa structure, the third mesa structure comprising: a third light-emitting layer; and a fourth connection layer formed on the third light-emitting layer and electrically connected to the third light-emitting layer; a third conductive adhesive layer formed under the third light-emitting layer; a fifth connection layer formed under the third conductive bonding layer and electrically connected to the third light-emitting layer via the third conductive bonding layer; 10. The micro LED structure of claim 1, comprising:

20. 20. A full color micro LED panel comprising a micro LED array, said micro LED array comprising the micro LED structure according to any one of claims 1 to 19.

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