Micro LED Structure and Micro LED Panel

Abstract

The micro-LED structure and full-color micro-LED panel disclosed herein include at least three mesa structures. A first dielectric layer is formed between a first interconnect layer and a second interconnect layer; a third interconnect layer is shared by the second and third mesa structures. The micro-LED structure can improve luminous efficiency and reduce crosstalk between adjacent micro-LEDs.

Description

TECHNICAL FIELD

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

[0002] Inorganic micro light emitting diodes are also known as "micro LEDs." They are increasingly important due to their use in various applications, including, for example, self-emissive micro displays, visible light communication, and optogenetics. Micro LEDs have greater output performance than conventional LEDs due to better strain relaxation, improved light extraction efficiency, uniform current spreading, etc. In addition, micro LEDs have improved thermal effects, improved operation at higher current density, better response rate, greater operating temperature range, higher resolution, higher color gamut, higher contrast, lower power consumption, etc. compared to conventional LEDs.

[0003] Micro LED panels are fabricated by integrating thousands or even millions of micro LEDs in an array with a backplane of drive circuitry. Each pixel of a micro LED panel is formed by one or more micro LEDs. A micro LED panel can be a single color or a multi-color panel. In particular, for multi-color LED panels, each pixel can further include multiple sub-pixels formed respectively by multiple micro LEDs, each micro LED corresponding to a different color. For example, three micro LEDs respectively corresponding to red, green, and blue colors 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 how to improve the effective illumination area within each pixel when the distance between adjacent LEDs is determined. In addition, it can be a difficult task to further improve the overall resolution of a micro LED panel when the individual LED illumination area is determined, as micro LEDs with different colors must occupy their designated areas within a single pixel.

[0005] In addition, the light emitted by the LED dies is generated by spontaneous emission and thus is not directional, resulting in a large angle of divergence. The large angle of divergence can cause various problems in a micro LED panel. On one hand, due to the large angle of divergence, only a small portion of the light emitted by a micro LED can be utilized. This can significantly reduce the efficiency and brightness of a micro LED display system. On the other hand, due to the large angle of divergence, the light emitted by one micro LED pixel can illuminate its neighboring pixels, causing light cross-talk between pixels, loss of clarity, and loss of contrast. SUMMARY

[0006] The present disclosure provides a micro-LED structure that addresses problems in the prior art, such as the problems described above. In particular, the disclosed micro-LED structure integrates two or more vertically stacked micro-LEDs by placing them in different layers of the micro-LED structure and electrically connecting them to an integrated circuit (IC) backplane. The micro-LED structure effectively enhances the light illumination efficiency within a single pixel area while improving the resolution of the micro-LED panel.

[0007] Furthermore, the disclosed micro-LED structure further improves the light illumination efficiency by including a reflective layer that not only effectively increases the amount of light emitted by each vertically stacked micro-LED but also reduces optical cross-talk 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. Each of the plurality of micro-LED structures corresponds to one pixel in the disclosed micro-LED structure, and the plurality of vertically stacked micro-LEDs in the pixel correspondingly to a plurality of sub-pixels.

[0009] In some embodiments, the disclosed micro-LED structure includes: an IC backplane; a mesa structure stack 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 can be located on the IC backplane and include: a first light emitting layer; a first top connection 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 can be located on the first mesa structure and 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 first mesa structure can not have a second connection layer, in that the first conductive bonding layer can bond the first light emitting layer to the IC backplane.

[0013] In some embodiments, a third mesa structure can be stacked on top of the second mesa structure. The third mesa structure can include the same layers as the second mesa structure, except that the third mesa structure does not have a third bottom connecting layer. Instead, the third light emitting layer can be electrically connected from its top to the second top connecting layer.

[0014] In some embodiments, each of the light emitting layers includes a P-type semiconductor layer, an N-type semiconductor layer, and a quantum well layer between the P-type semiconductor layer and the N-type semiconductor layer. For example, each of the light emitting layers can include a P-type semiconductor layer at the bottom and an N-type semiconductor layer at the top, thereby forming a P-N junction; or alternatively, each of the light emitting layers can include an N-type semiconductor layer at the bottom and a P-type semiconductor layer at the top, thereby forming an N-P junction. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1A is a cross-sectional view of a micro-LED structure according to some embodiments of the present disclosure;

[0016] Figure 1B is a top view of an exemplary micro-LED structure according to some embodiments of the present disclosure;

[0017] Figure 1C is a top view of another exemplary micro-LED structure according to some embodiments of the present disclosure;

[0018] Figure 1D is a top view of an exemplary micro-LED panel according to some embodiments of the present disclosure;

[0019] Figure 1E is a top view of another exemplary micro-LED panel according to some embodiments of the present disclosure;

[0020] Figure 2 is a cross-sectional view of another micro-LED structure according to some embodiments of the present disclosure;

[0021] Figure 3 is a cross-sectional view of another micro-LED structure according to some embodiments of the present disclosure;

[0022] Figure 4 is a cross-sectional view of another micro-LED structure according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0023] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings, in order to provide a further understanding of the present disclosure. The specific embodiments and drawings discussed are merely illustrative of specific ways to make and use the present disclosure and do not limit the scope of the present disclosure or the appended claims.

[0024] Figure 1A This is a cross-sectional view of a micro-LED structure 10 according to some embodiments of this disclosure. (See also:) Figure 1A As shown, the micro-LED structure 10 includes an IC backplane 900 and three mesa structures. Specifically, among the three mesa structures, the first mesa structure, from bottom to top, includes a first conductive bonding layer 103, a first light-emitting layer 100 (e.g., a layer emitting 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. The second mesa structure of the micro-LED structure 10, from bottom to top, includes a second bottom connection layer 202, a second conductive bonding layer 203, a second light-emitting layer 200 (e.g., a layer emitting 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, from bottom to top, includes a third conductive bonding layer 303, a third light-emitting layer 300 (e.g., a layer emitting blue light), and a third top connection layer 301. A second top connection layer 201 is bonded to and electrically connected to the third light-emitting layer 300. These three mesa structures are stacked on an 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 accordingly.

[0025] Continue to refer to Figure 1A In some embodiments, dielectric material 700 may be filled between top interconnect layer 101 and bottom interconnect layer 202, thus forming dielectric layer 701 between the first top interconnect layer 101 and the second bottom interconnect layer 202. In some embodiments, dielectric material 700 may be filled in the gaps of microLED structure 10, thereby isolating light-emitting layers (e.g., light-emitting layers 100, 200, 300) from electrical connection with each other.

[0026] In some embodiments, light-emitting layers 100, 200, and 300 can emit light or light images of different colors. In some exemplary embodiments, the first light-emitting layer 100 is selected as a red light-emitting layer, the second light-emitting layer 200 is selected as a green light-emitting layer, and the 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 obtain any desired results.

[0027] When the mesa structures of the micro-LED structure 10 are vertically projected onto a horizontal plane, each of the mesa structures forms a projection area on the horizontal plane. Each projection area on the horizontal plane has a profile, which is referred to herein as the projection profile in a plan view (i.e., a top view). In some embodiments, the disclosed micro-LED structure is configured such that the projection profile of the upper light-emitting layer in the plan view lies within the projection shape of the lower light-emitting layer in the plan view, thereby forming a plurality of mesa structures with different widths. Specifically, Figure 1B yes Figure 1A A top view of the micro-LED structure 10. (See attached image.) Figure 1B As shown, R, G, and B respectively represent the regions of the light-emitting layers 100, 200, and 300 formed in the top view. In this exemplary embodiment, the projected outline of the light-emitting layer 300 lies within the projected outline of the light-emitting layer 200; and the projected outline of the light-emitting layer 200 lies within the outline of the light-emitting layer 100.

[0028] Return to reference Figure 1A In the exemplary embodiments shown therein, the sidewalls of conductive bonding layers 103, 203, and 303 are respectively aligned with the sidewalls of light-emitting layers 100, 200, and 300. Specifically, the sidewall of conductive bonding layer 103 is aligned with the sidewall of light-emitting layer 100; the sidewall of conductive bonding layer 203 is aligned with the sidewall of light-emitting layer 200; and the sidewall of conductive bonding layer 303 is aligned with the sidewall of light-emitting layer 300.

[0029] In some embodiments, the conductive bonding layer can be transparent or opaque. In some embodiments, the material of the conductive bonding layer is selected from metals, composite metals, or transparent conductive materials. In some embodiments, the transparent conductive material can be made of transparent plastic (resin) or silicon dioxide (SiO2), such as spin-coated glass (SOG), adhesive MicroResist BCL-1200, etc. The metal can be selected from copper (Cu), gold (Au), etc. In some embodiments, the thickness of the conductive bonding layer (e.g., 103, 203, 303) can range from about 0.1 micrometers to about 5 micrometers. In some embodiments, the metal composition used for the bonding layer can include Au-Au bonding, Au-Sn bonding, Au-In bonding, Ti-Ti bonding, Cu-Cu bonding, or combinations thereof. For example, when Au-Au bonding is required, each of the two Au layers needs a chromium (Cr) coating as an adhesion layer, and a platinum (Pt) coating is needed between the gold layer and the chromium coating as an anti-diffusion layer. The Cr layer and the Pt layer can be formed on the two Au layers to be bonded. In some implementations, when the two Au layers to be bonded are approximately the same thickness, interdiffusion of Au on the two Au layers under high pressure and high temperature can bond the two layers together. Example bonding techniques may include eutectic bonding, thermocompression bonding, and transient liquid phase (TLP).

[0030] In some embodiments, the materials of the top interconnect layers 101, 201, 301 and the bottom interconnect layer 202 can be selected from transparent conductive materials. In some embodiments, the transparent conductive material can be indium tin oxide (ITO). In some embodiments, the thickness of the ITO layer can range from about 0.01 micrometers to about 1 micrometer.

[0031] In some embodiments, the second and third mezzanine structures are joined by a second top connecting layer 201. The sidewalls of the second top connecting layer 201 may be aligned with the second light-emitting layer and are considered as layers of the second mezzanine structure. In other words, both the second light-emitting layer 200 and the third light-emitting layer 300 are electrically connected to the second top connecting layer 201. In some embodiments, the second light-emitting layer 200 may have its entire area covered by the second top connecting layer 201, and thus its entire area is utilized.

[0032] In some embodiments, the vias 400 of the common interconnect layer filled with conductive metal can be formed adjacent to the light-emitting layers 100, 200, and 300 and adjacent to the mesa structure stack. In some exemplary embodiments, such as Figure 1AAs shown, the common connection layer via 400 is electrically connected to the light-emitting layers 100, 200, and 300 via top connection layers 101 and 201. In some embodiments, a top contact pad 401 may be formed on top of the common connection layer via 400. The top contact pad 401 may be electrically connected to a circuit system outside the micro-LED structure 10.

[0033] In some embodiments, at least one of the anode connection layer vias 500 and 600 may be formed adjacent to the stacked mesa structure of the micro-LED structure 10. The anode connection layer vias 500 and 600 are formed at locations separate from the common connection layer via 400. For example, the anode connection layer vias 500 and 600 may be located on a different side of the mesa structure from the common connection layer via 400. The vias 400, 500, and 600 are not electrically connected to each other.

[0034] In one exemplary implementation, such as Figure 1A As shown, the anode connection layer via 500 connects the light-emitting layer 200 to the IC backplane 900 via the second bottom connection layer 202. Furthermore, the anode connection layer via 600 connects the light-emitting layer 300 to the IC backplane 900 via the top connection layer 301. In this exemplary embodiment, the first light-emitting layer 100 is electrically connected to the IC backplane 900 via the conductive bonding layer 103, and therefore, a connection layer via is not required to connect the first light-emitting layer 100 to the IC backplane 900.

[0035] Figure 1B The illustration schematically demonstrates, according to an exemplary implementation scheme, Figure 1A A top view of the micro-LED structure 10. The dashed rectangles correspondingly represent the bottom connecting layers 202 and 302. Other layers are not shown in the diagram for better explanation of the relevant structural features. Figure 1B As shown in the image. Figure 1B As shown, the top contact pad 401 is formed on the side of the mesa structure opposite to the anode connection vias 500 and 600. The anode connection vias 500 and 600 are formed in a direction perpendicular to the adjacent edges of the mesa structure.

[0036] Figure 1C This schematically illustrates a different exemplary implementation. Figure 1A A top view of the micro-LED structure 10. (See attached image.) Figure 1C As shown, the anode connection layer through holes 500 and 600 are formed in a direction parallel to the adjacent edges of the mesa structure. Figure 1B and Figure 1C The implementation scheme shown is for illustrative purposes only. Common connection layer vias and anode connection layer vias can be formed anywhere within the micro-LED region.

[0037] Figure 1DThis is a top view of a micro LED panel 11 according to an exemplary embodiment. Figure 1D As shown, the micro-LED panel 11 includes an array of micro-LED structures 10. (As...) Figure 1D As shown, the top contact pads 401 of multiple micro-LED structures 10 in each row are connected together to form a continuous line. Shared contact pads 402 connect the top contact pads 401 of all rows together. In this exemplary embodiment, the distribution direction of the anode connection layer vias 500, 600 is perpendicular to the distribution direction of the top contact pads 401.

[0038] Figure 1E This is a top view of a micro LED panel 11 according to another exemplary embodiment. Figure 1E As shown, adjacent rows of micro-LEDs share a top contact pad 401. This arrangement further increases the integration of the micro-LED panel.

[0039] In some embodiments, each mezzanine structure may further include a reflective layer. The reflective layer in each mezzanine structure may be formed on the bottom surface of a corresponding light-emitting layer or on the bottom surface of a corresponding conductive bonding layer. Furthermore, reflective layers may be formed between mezzanine structures, for example, between the bottom bonding layer of a higher mezzanine structure and the top bonding layer of a lower mezzanine structure. (The following is in conjunction with...) Figures 2-4 These implementation schemes are described in detail.

[0040] Figure 2 This is a cross-sectional view of a microLED structure 20 according to some exemplary embodiments. The microLED structure 20 is a microLED structure 10 ( Figure 1A A variant of ). Figure 1A and Figure 3 The same numbers in the text refer to the same structure, and their details will not be repeated here. The following only explains... Figure 1A and Figure 2 The differences between them. For example Figure 2As shown, 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 correspondingly formed on the bottom surface of the light-emitting layers 100, 200, 300. The sidewalls of reflective layers 104, 204, 304 are correspondingly aligned with the sidewalls of the light-emitting layers 100, 200, 300 in the mesa structure. For example, in the bottom mesa structure, a 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 the middle mesa structure, a 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 the top mesa structure, a 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 in the micro-LED structure 20 includes a stacked transparent layer and a metal omnidirectional reflection (ODR) layer, a stacked distributed Bragg reflection (DBR) layer, or a high-reflectivity metal. In some embodiments, the thickness of the reflective layer ranges from about 0.1 micrometers to about 5 micrometers.

[0041] In some embodiments, the reflective layer (e.g., 104, 204, or 304) may be an insulating layer (e.g., a dielectric DBR layer). Sidewall connection layers may be added to provide electrical continuity between the light-emitting layer (e.g., 100, 200, 300) and the conductive bonding layer (e.g., 103, 203, 303). For example, sidewall connection layer 310 may provide an electrical connection between the light-emitting layer 300 and the conductive bonding layer 303. Similar sidewall connection layers may be added to the first mezzanine structure and / or the second mezzanine structure as needed.

[0042] Figure 3 This is a cross-sectional view of a microLED structure 30 according to some exemplary embodiments. The microLED structure 30 is a microLED structure 10 ( Figure 1A A variant of ). Figure 1A and Figure 3 The same numbers in the text refer to the same structure, and their details will not be repeated here. The following only explains... Figure 1A and Figure 3 The differences between them. For example Figure 3As shown, reflective layers 105, 205, and 305 are respectively formed on the bottom surfaces of conductive bonding layers 103, 203, and 303. Similarly, the sidewalls of reflective layers 105, 205, and 305 are respectively aligned with the sidewalls of conductive bonding layers 103, 203, and 303 in the mezzanine structure. For example, in the bottom mezzanine structure, reflective layer 105 is formed on the bottom surface of conductive bonding layer 103, and the sidewall of conductive bonding layer 103 is aligned with the sidewall of the corresponding reflective layer 105; in the middle mezzanine structure, reflective layer 205 is formed on the bottom surface of conductive bonding layer 203, and the sidewall of conductive bonding layer 203 is aligned with the sidewall of the corresponding reflective layer 205; and in the top mezzanine structure, reflective layer 305 is formed on the bottom surface of conductive bonding layer 303, and the sidewall of conductive bonding layer 303 is aligned with the sidewall of the corresponding reflective layer 305. In some implementations, each of the reflective layers in the micro-LED structure 30 includes a stacked transparent layer and a metal ODR layer, a stacked DBR layer, or a highly reflective metal.

[0043] In some implementations, the reflective layer (e.g., 105, 205, or 305) may be an insulating layer (e.g., a dielectric DBR layer). Sidewall connection layers may be added to provide electrical continuity between the light-emitting layer (e.g., 100, 200, 300) and the connection layer or IC backplane (e.g., 201, 202, 900). For example, sidewall connection layer 310 may provide an electrical connection between the light-emitting layer 300 and the second top connection layer 201. Similar sidewall connection layers may be added to the first mezzanine structure and / or the second mezzanine structure as needed.

[0044] Figure 4 This is a cross-sectional view of a microLED structure 40 according to some embodiments of this disclosure. The microLED structure 40 is a microLED structure 10 ( Figure 1A A variant of ). With Figure 1A compared to, Figure 4 The same numbers in the text refer to the same structure, and their details will not be repeated here. The following only explains the relationship with... Figure 4 The differences. For example Figure 4As shown, a transparent reflective layer (e.g., 106 or 206) is formed on top of a top connecting layer (e.g., 101, 201). For example, between the top connecting layer of the first mezzanine structure and the bottom connecting layer of the second mezzanine structure, and between the top connecting layer of the second mezzanine structure and the third conductive bonding layer 303. In this exemplary embodiment, the sidewalls of the transparent reflective layers 106, 206 may be aligned with the sidewalls of the light-emitting layers of the second and third mezzanine structures (e.g., 200, 300 respectively). That is, the transparent reflective layer 106 is formed on the first top connecting layer 101 and at the bottom of the second bottom connecting layer 202 of the intermediate mezzanine structure, and the sidewalls of the transparent reflective layer 106 are aligned with the sidewalls of the light-emitting layer 200 of the second mezzanine structure; the transparent reflective layer 206 is formed on the second top connecting layer 201 and at the bottom of the third conductive bonding layer 303 of the top mezzanine structure, and the sidewalls of the transparent reflective layer 206 are aligned with the sidewalls of the light-emitting layer 300 of the third mezzanine structure. Transparent reflective layers 106 and 206 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 light-emitting layer 100 is reflected by transparent reflective layer 106, which has a higher reflectivity than conductive bonding layer 203. Similarly, upward light (e.g., green light) emitted from light-emitting layer 200 is reflected by transparent reflective layer 206, which has a higher reflectivity than conductive bonding layer 303.

[0045] In some implementations, the reflective layer (e.g., 106, 206) may be an insulating layer (e.g., a dielectric DBR layer). Sidewall connection layers may be added to provide electrical continuity between the light-emitting layer (e.g., 200, 300) and the connection layer (e.g., 101, 201). For example, sidewall connection layer 310 may provide an electrical connection between the light-emitting layer 300 and the second top connection layer 201. Similar sidewall connection layers may be added to the second mezzanine structure as needed.

[0046] In some embodiments, each of the aforementioned reflective layers may comprise a distributed Bragg reflector (DBR) structure. For example, the reflective layer can be formed by stacking multiple layers of alternating or different materials with different refractive indices. In some embodiments, each layer boundary of the DBR structure can 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 SiO2 and Ti3O5 layers, or by manipulating the thickness and / or number of Au and / or ITO layers, selective reflection or transmission of light of a specific wavelength can be achieved. For example, in an exemplary design, Figure 4 The reflective layer 106 in the middle reflects red light; and Figure 4The reflective layer 206 in the structure reflects green light. For example, the following DBR structures shown in Table 1 can be used as reflective layers to reflect green light from the green light-emitting layer:

[0047] Table 1: DBR layer structure of the green light reflector.

[0048]

[0049]

[0050] In some embodiments, the reflective layer 204 for the green LED structure may have a low absorptivity (e.g., equal to or less than 5%) for light generated by different layers of the tri-color LED device. In some embodiments, the reflective layer 204 for the green layer has a high reflectivity (e.g., equal to or greater than 95%) for light generated above it (e.g., green and blue light).

[0051] In some exemplary embodiments, in the microLED structure 10 ( Figure 1A ), 20 Figure 2 ), 30 Figure 3 ) or 40 Figure 4 The first light-emitting layer 100 in the image 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 film within the red light-emitting layer may comprise a layer of P-type (Al)(In)(Ga)P / P-type (Al)InGaP light-emitting layer / N-type (Al)(In)(Ga)P / N-type GaAs. In some embodiments, the P-type may be Mg-doped or carbon-doped, and the N-type may be Si-doped. In some embodiments, the thickness of the light-emitting layer 100 may range from about 0.3 micrometers to about 5 micrometers.

[0052] In some implementations, in the micro-LED structure 10 ( Figure 1A ), 20 Figure 2 ), 30 Figure 3 ) or 40 Figure 4 The second light-emitting layer 200 in the [structure / structure] 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 film within the green light-emitting layer 200 may comprise a layer of P-type GaN / InGaN light-emitting layer / N-type GaN. 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 range from about 0.3 micrometers to about 5 micrometers.

[0053] In some implementations, in the micro-LED structure 10 ( Figure 1A ), 20 Figure 2 ), 30 Figure 3 ) or 40 Figure 4 The light-emitting layer 300 in the [structure / structure] 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 film within the blue light-emitting layer 300 may comprise a layer of P-type GaN / InGaN light-emitting layer / N-type GaN. 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 range from about 0.3 micrometers to about 5 micrometers.

[0054] In some implementations, in the micro-LED structure 10 ( Figure 1A ), 20 Figure 2 ), 30 Figure 3 ) or 40 Figure 4 In this process, a topmost interconnecting layer (e.g., a third top interconnecting layer 302) is deposited on the light-emitting layer 300. In some embodiments, the thickness of the third top interconnecting layer 302 (ITO layer) can range from about 0.01 micrometers to about 1 micrometer.

[0055] In some implementations, the microlens 800 can be formed in the micro-LED structure (e.g., as shown in the image). Figure 1A and Figures 2-4 On top of the micro-LED structure shown.

[0056] The microLEDs described in the disclosed embodiments have very small volumetric dimensions. MicroLEDs can be organic or inorganic LEDs. In some embodiments, microLEDs can be used in a microLED array panel. The light-emitting area of ​​the microLED array panel can be very small, for example, 1mm × 1mm, 3mm × 5mm, etc. In some embodiments, the light-emitting area can be an area of ​​the microLED array within the microLED array panel. The microLED array panel can include one or more microLED arrays forming a pixel array, for example, a 1600 × 1200, 680 × 480, or 1920 × 1080 pixel array, where the microLEDs are pixels. The diameter of the microLEDs can range from about 200nm to 2μm. In some embodiments, an IC backplane can be formed on the back surface of the microLED array and electrically connected to the microLED array. In some embodiments, the IC backplane can acquire signals such as image data from the outside via signal lines to control the on / off state (e.g., emitting light or not emitting light) of the corresponding microLEDs.

[0057] Therefore, different types of display panels can be manufactured. For example, in some implementations, the resolution of the display panel can range from 8×8 to 3840×2160. Common display resolutions include QVGA (320×240 with a 4:3 aspect ratio), XGA (1024×768 with a 4:3 aspect ratio), D (1280×720 with a 16:9 aspect ratio), FHD (1920×1080 with a 16:9 aspect ratio), UHD (3840×2160 with a 16:9 aspect ratio), and 4K (4096×2160 with a 1.9 aspect ratio). A wide variety of pixel sizes are also possible, ranging from submicron and below to 10mm and above. The size of the entire display area can also vary widely, ranging from small to tens of micrometers or smaller diagonally to hundreds of inches or larger.

[0058] Those skilled in the art will understand that the micro LED display panel is not limited to the structure described above, and may include more or fewer components than those shown in the figures, or may combine some components, or may use different components.

[0059] It should be noted that relational terms in this document, such as “first” and “second”, are used only to distinguish an entity or operation from another entity or operation, without requiring or implying any actual relationship or order between these entities or operations. Furthermore, the words “comprising,” “having,” “containing,” and “including,” and other similar forms, are intended to be semantically equivalent and are open-ended; one or more items following any of these words do not imply an exhaustive list of such items or that the list is limited to only one or more items.

[0060] As used herein, unless otherwise expressly stated, the term "or" covers all possible combinations unless impractical. For example, if a database is declared to include A or B, then unless otherwise expressly stated or impractical, the database may include A, or B, or A and B. As a second example, if a database is declared to include A, B, or C, then unless otherwise expressly stated or impractical, the database may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0061] Those skilled in the art will understand that all or part of the steps for implementing the aforementioned embodiments can be implemented in hardware, or by a program instructing the relevant hardware. The program can be stored in the aforementioned flash memory, in the aforementioned conventional computer device, in the aforementioned central processing module, in the aforementioned adjustment module, etc.

[0062] The above description is merely an embodiment of this disclosure, and this disclosure is not limited thereto. Any modifications, equivalent substitutions, and improvements made without departing from the concept and principles of this disclosure shall fall within the protection scope of this disclosure.

Claims

1. A micro-LED structure, comprising: an IC backplane; a first mesa structure formed on the IC backplane, the first mesa structure comprising a first connection layer; a first dielectric layer formed on the first mesa structure; a second mesa structure formed on the first dielectric layer, the second mesa structure comprising a second connection layer and a third connection layer; and a third mesa structure formed on the third connection layer, the third mesa structure comprising a fourth connection layer; wherein the second connection layer and the fourth connection layer are electrically connected to the IC backplane; wherein the first connection layer is electrically connected to the third connection layer; wherein the third connection layer is electrically connected to a bottom surface of the third mesa structure; and wherein each of the first mesa structure, the second mesa structure, and the third mesa structure comprises a light-emitting layer, the light-emitting layer comprising: a first epitaxial layer having a first conductivity type; a quantum well layer on the first epitaxial layer; and a second epitaxial layer on the quantum well layer, the second epitaxial layer having a second conductivity type; wherein the third mesa structure comprises a sidewall connection layer connecting the light-emitting layer of the third mesa structure and the third connection layer of the second mesa structure; wherein the first mesa structure, the second mesa structure, and the third mesa structure form a first profile, a second profile, and a third profile, respectively, in plan view, the third profile disposed within the second profile, the second profile disposed within the first profile; wherein the micro-LED structure further comprises: a first bonding layer formed below the first mesa structure, the first bonding layer bonding a bottom surface of the first mesa structure to the IC backplane; a second bonding layer formed between the second connection layer and a remaining portion of the second mesa structure, the second bonding layer bonding a bottom surface of the remaining portion of the second mesa structure to the second connection layer; and a third bonding layer formed between the third connection layer and a remaining portion of the third mesa structure, the third bonding layer bonding a bottom surface of the remaining portion of the third mesa structure to the third connection layer; wherein sidewalls of the first bonding layer are vertically aligned with sidewalls of the light-emitting layer of the first mesa structure, sidewalls of the second bonding layer are vertically aligned with sidewalls of the light-emitting layer of the second mesa structure, and sidewalls of the third bonding layer are vertically aligned with sidewalls of the light-emitting layer of the third mesa structure.

2. The micro-LED structure of claim 1, wherein, each of the first bonding layer, the second bonding layer, and the third bonding layer comprises: a metal; a composite metal; or a transparent conductive material.

3. The micro-LED structure of claim 2, wherein, the transparent conductive material is silicon dioxide (SiO2) or indium tin oxide (ITO).

4. The micro-LED structure of claim 1, wherein, the first dielectric layer comprises a first reflective layer.

5. The micro-LED structure of claim 2, wherein, the transparent conductive material is indium tin oxide (ITO).

6. The micro-LED structure of claim 4, wherein, sidewalls of the first reflective layer are aligned with sidewalls of the second mesa structure.

7. The micro-LED structure of claim 6, wherein, the first reflective layer comprises: a stacked transparent layer; a metal omnidirectional reflective (ODR) layer; a stacked distributed Bragg reflector (DBR) layer; or a high reflectivity metal.

8. The micro-LED structure of claim 6, wherein, The first reflective layer is electrically insulating.

9. The micro-LED structure of claim 4, wherein, The first reflective layer, the first connecting layer, and the second connecting layer are transparent.

10. The micro-LED structure of claim 4, further comprising a second reflective layer formed between the third connecting layer and the third bonding layer.

11. The micro-LED structure of claim 10, wherein, A sidewall of the second reflective layer is aligned with a sidewall of the third mesa structure.

12. The micro-LED structure of claim 11, wherein, The second reflective layer comprises: a stack of transparent layers and metal omnidirectional reflective (ODR) layers; a stack of distributed Bragg reflective (DBR) layers; or a high reflectivity metal.

13. The micro-LED structure of claim 10, wherein, The second reflective layer and the third connecting layer are transparent.

14. The micro-LED structure of claim 10, wherein, The second reflective layer is electrically insulating.

15. The micro-LED structure of claim 10, wherein, The sidewall connecting layer is formed immediately adjacent to a sidewall of the second reflective layer and a sidewall of the third bonding layer and is configured to connect the sidewall of the second reflective layer and the sidewall of the third bonding layer.

16. The micro-LED structure of claim 1, wherein, Each of the first connecting layer, the second connecting layer, and the third connecting layer comprises a transparent conductive material.

17. The micro-LED structure of claim 1, further comprising a first via formed immediately adjacent to one or more of the first mesa structure, the second mesa structure, and the third mesa structure, the first via electrically connected to the first connecting layer and the third connecting layer.

18. The micro-LED structure of claim 17, further comprising a second via and a third via formed proximate to one or more of the first mesa structure, the second mesa structure, and the third mesa structure, wherein, The second via connects the second connecting layer to the IC backplane, and the third via connects the fourth connecting layer to the IC backplane.

19. The micro-LED structure of claim 1, wherein: The first conductivity type is a P-type semiconductor, and The second conductivity type is an N-type semiconductor.

20. The micro-LED structure of claim 1, wherein: The first conductivity type is an N-type semiconductor, and The second conductivity type is a P-type semiconductor.

21. A full color micro-LED panel comprising a micro-LED array, wherein, The micro-LED array comprises the micro-LED structure of any one of claims 1-20.

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