Micro-assembly LED display

Abstract

The present invention relates to micro-assembled LED displays. The disclosed technology provides micro-assembled micro-LED displays and lighting elements using arrays of micro-LEDs that are too small (e.g., micro-LEDs having a width or diameter of 10 μm to 50 μm), numerous, or fragile to be assembled by conventional means. The disclosed technology provides micro-LED displays and lighting elements assembled using micro-transfer printing techniques. The micro-LEDs can be prepared on a homogenous substrate and printed onto a display substrate (e.g., plastic, metal, glass, or other material), thereby avoiding the need to manufacture the micro-LEDs on the display substrate. In certain embodiments, the display substrate is transparent and / or flexible.

Description

[0001] Information about divisional applications

[0002] This case is a divisional application based on the unity issue. The parent case of the divisional application is the invention patent application No. 201811574241.1 with the application date of June 18, 2015 and the invention name of “Micro-assembled LED display”. The invention patent application No. 201811574241.1 is also a divisional application, and its parent case is the invention patent application No. 201580042604.5 with the invention name of “Micro-assembled LED display” after the international application No. PCT / EP2015 / 063709 with the application date of June 18, 2015 entered China.

[0003] Related Applications

[0004] This application claims priority to and the benefit of the following U.S. Provisional Patent Applications: U.S. Provisional Patent Application No. 62 / 014,077, filed on June 18, 2014, entitled “Micro Assembled LED Displays and Lighting Elements”; U.S. Provisional Patent Application No. 62 / 026,695, filed on July 20, 2014, entitled “Micro Assembled LED Displays and Lighting Elements”; U.S. Provisional Patent Application No. 62 / 029,533, filed on July 27, 2014, entitled “Micro Assembled LED Displays and Lighting Elements”; U.S. Provisional Patent Application No. 62 / 030,696, filed on September 25, 2014, entitled “Interconnection Architectures Advantageous for Micro-LED Displays Assembled via Micro Transfer Printing”; and U.S. Provisional Patent Application No. 62 / 031,697, filed on July 20, 2014, entitled “Micro Assembled LED Displays and Lighting Elements”. U.S. Provisional Patent Application No. 62 / 055,485, filed on September 26, 2014, entitled “Interconnect Architecture Advantages of Micro LED Displays Assembled Via Micro Transfer Printing”; U.S. Provisional Patent Application No. 62 / 056,419, filed on September 26, 2014, entitled “Passive Matrix Display with Bottom Emitting Inorganic Micro Scale Light Emitting Diodes”; U.S. Provisional Patent Application No. 62 / 131,230, filed on March 10, 2014, entitled “Passive Matrix Display with Bottom Emitting Inorganic Micro Scale Light Emitting Diodes”; U.S. Provisional Patent Application No. 62 / 131,230, filed on March 10, 2014, entitled “Micro Assembled Micro LED Displays and Lighting Elements”; U.S. Provisional Patent Application No. 62 / 131,230, filed on April 16, 2015, entitled “Micro Assembled Micro LED Displays and Lighting Elements”; and U.S. Provisional Patent Application No. 62 / 169,531, filed on June 1, 2015, entitled “Micro-Assembled Micro-LED Display and Lighting Elements,” the contents of each of which are incorporated herein by reference in their entirety. Technical Field

[0005] Described herein are micro-assembled inorganic light emitting diode (ie, micro-LED) displays and lighting elements featuring arrays of micro-LEDs that are too small, numerous, or too fragile to be assembled by conventional means. Background Art

[0006] Flat panel displays are typically constructed with an array of light emitters distributed over the surface of a flat substrate. With the exception of plasma televisions, emissive flat panel displays typically rely on (i) a backlight with pixel light control provided by liquid crystals and color filters (e.g., liquid crystal displays), (ii) organic color light emitters (e.g., organic light emitting diode displays), or (iii) organic white light emitters with color filters (e.g., white organic light emitting diode displays). Importantly, all three of these flat panel display technologies are area emitters, i.e., the entire area of ​​each pixel is filled with light emitters or light controllers. Most of these displays are active matrix displays that rely on local circuits formed on the substrate to control the pixels. These circuits (a single transistor for liquid crystal displays and two or more transistors for organic light emitting diode displays) require significant area on the substrate, which reduces the area available for light emission. Organic light emitting diode displays typically have a 60% fill factor (also referred to as active light emitting area or aperture ratio), and liquid crystal displays can have even larger fill factors depending on the display size and resolution.

[0007] Inorganic light emitting diodes (LEDs) are typically manufactured using a semiconductor process that requires the use of various chemicals and materials. This manufacturing method requires the use of a rigid substrate (e.g., a sapphire substrate or a silicon substrate) that does not melt during the high temperature manufacturing process. After the LEDs are fabricated on the rigid substrate, the wafer is typically cut to form individual LEDs for use in displays.

[0008] Early LED applications in displays include handheld calculators with numerical LED displays. Recently, LEDs have been integrated as backlights for displays. Integrating LEDs into larger displays (such as display panels) involves complex wiring for each individual LED in the display panel. Using LEDs for displays (such as RGB LED displays) continues to present numerous challenges, including increased complexity, limited display formats, increased manufacturing costs, and reduced manufacturing yields. For example, a display with a resolution of 1280×720 includes 921,600 pixels. For RGB LED displays, each pixel must typically include three LEDs (red, green, and blue LEDs) in each pixel. Therefore, the display must use 2,764,800 LEDs in this example. In some cases, all of these LEDs must be arranged in a display that measures several inches diagonally. Not only must these LEDs be smaller, but the LEDs must be arranged into arrays with appropriate wiring and drive circuits. In addition, the materials used to form the LEDs of each color are different. It is extremely difficult to arrange different color LEDs as needed during manufacturing for RGB displays. Semiconductor chip or die automated assembly equipment typically uses a vacuum operated placement head (such as a vacuum gripper or pick and place tool) to pick up and apply the device to a substrate. It is difficult to pick up and place ultra-thin and small devices using this technology.

[0009] Furthermore, LEDs are typically formed with terminals on different faces of the micro-LED. These vertical LEDs encounter challenges in electrically isolating the anode and cathode during the interconnection process. This requires depositing vertical insulators between the terminals in, for example, robotic assembly of LED displays. For example, if one terminal is on the bottom and one terminal is on the top, the terminals occupy the same space in the xy plane and require a robust insulator. Forming vertical electrical insulation between the two terminals of an LED at the panel level adds extra steps and layers to the display, adding increased complexity in display applications.

[0010] For these reasons and others, it is difficult and expensive to provide consumers with high-resolution RGB LED displays. Therefore, there is a need for systems and methods for manufacturing displays using LEDs that provide low-cost manufacturing, improved yields, and improved system reliability. Summary of the invention

[0011] Described herein are micro-assembled inorganic light emitting diode (e.g., micro-LED) displays and lighting elements featuring arrays of micro-LEDs that are too small, numerous, or too fragile to be assembled by conventional means (e.g., micro-LEDs having a width, length, height, and / or diameter of 0.5 μm to 50 μm; e.g., a width of 1 μm to 50 μm, a length of 5 μm to 500 μm, and a height of 0.5 μm to 50 μm). Specifically, these displays are assembled using micro-transfer printing techniques. The micro-LEDs may be prepared on a homogeneous substrate using high temperature manufacturing techniques and printed onto a non-homogeneous display substrate (e.g., a polymer, plastic, resin, polyimide, polyethylene naphthalate, polyethylene terephthalate, metal, metal foil, glass, and sapphire, a transparent material, or a flexible material that is separate and distinct from the homogeneous substrate on which the micro-LEDs were originally fabricated), thereby avoiding fabrication of the micro-LEDs on the display substrate, which, among other things, cannot withstand the temperatures required to construct semiconductor elements.

[0012] The micro-LEDs printed by micro-transfer are bright (e.g., from 300 W / cm 2 Up to 700W / cm 2 The display can utilize a transparent (e.g., plastic, sapphire, or glass) substrate, and can be made lightweight or flexible, or both. Because the micro-LEDs occupy a small portion of the display area, and because the micro-LED wiring can be thin or transparent, the display itself can be transparent or translucent. The display can emit light from the front, back, or both sides. In some embodiments, the display has an adhesive layer on one side, resulting in a sticker-like display.

[0013] Sparsely distributed micro-LEDs allow new functionality including micro-sensors, power harvesting devices, gesture sensors (both contact and contactless), image capture devices, etc. The display may also include micro-transfer printed micro-integrated circuits that provide CMOS performance and, in some embodiments, embedded memory (e.g., non-volatile memory).

[0014] The active light emitting area of ​​an LED pixel is small and occupies a minimal pixel area relative to conventional displays in which the semiconductor material occupies the entire display panel or a substantial portion thereof. For example, the semiconductor material in the disclosed displays is required only in the locations of the active elements, e.g., in certain embodiments, it covers no more than 40%, 30%, 20%, 10%, 5%, 3%, 1%, 0.5%, or 0.1% of the viewing area of ​​the display. Thus, due in part to the brightness of the micro-LEDs, the efficiency of the crystalline semiconductor substrates, and the ability to assemble the micro-LEDs into arrays using the manufacturing techniques described herein, it is possible to manufacture displays with low fill factors (e.g., no more than 40%, 30%, 20%, 10%, 5%, 3%, 1%, 0.5%, or 0.1%) without compromising the quality of the display.

[0015] For example, in some embodiments, the driving circuit is located in one or more pixels (e.g., on the same layer as the micro-LEDs). For example, the driving circuit may use only a small portion of the pixel (e.g., an area of ​​10 μm to 60 μm by 5 μm to 50 μm, for example). The circuitry required to drive the micro-LEDs may consume, for example, less than 10%, 5%, 1%, 0.5%, or 0.1% of the pixel area, thereby allowing the space to be used for other purposes and / or improved transparency. For example, more complex circuits or multiple emitters may be placed at each pixel location without loss of light emission or efficiency. In contrast, if multiple emitters and / or other active elements are included at each pixel location using other flat panel display technologies, the area available for each pixel will be reduced, thereby resulting in reduced light output or service life. Therefore, the disclosed micro-LED display, including, for example, a display utilizing micro-LEDs on a display substrate, allows more complexity, additional light emitters, or additional functionality to be placed in each pixel without significantly affecting (e.g., without any image) the display quality.

[0016] In certain embodiments, a 99.99% or greater yield is achieved by micro-transfer printing of micro-LEDs to a display substrate. Positioning multiple inorganic micro-LEDs at each pixel site achieves several possible technical advantages. In addition, the display yield can be increased by positioning redundant inorganic micro-LEDs at each light emitter or pixel site. For example, in some embodiments, the display yield is improved by using two or more identical light emitters at each pixel site because (for example) the display appears to function properly even if one light emitter at each pixel site (for example) is faulty. In certain embodiments, when it is determined that the primary micro-LED is faulty (for example, during manufacturing or before display distribution), the redundant micro-LED is electrically connected to the display.

[0017] In addition, in some embodiments, additional emitters of different colors are provided within the pixel at no significant cost in substrate area or pixel performance. Additional colors can, for example, widen the color gamut by adding yellow or cyan to conventional red, green, and blue emitters. In some embodiments, a 3D display is provided using the disclosed technology. For example, in some embodiments, a display utilizes two slightly different red, green, and blue emitters, thereby providing a 3D display without reducing the display frame rate. More complex control schemes are possible, such as, for example, updating as needed. In addition, in some embodiments, local light sensors can be used to locally (or globally) calibrate the micro-LEDs (e.g., in real time). In certain embodiments, in addition to the micro-LEDs, other micro devices can also be placed within each pixel. For example, micro sensing and micro integrated circuits (e.g., micro display drivers) can be placed within the pixel. In some embodiments, an antenna is located within each pixel. The antenna can be used to stream power or data into the display using wireless signals / communications.

[0018] In certain embodiments, the disclosed technology includes an advantageous interconnect architecture for micro-LED displays, for example, displays assembled via micro-transfer printing.

[0019] Typically, LEDs are formed with terminals on different faces of a micro-LED. Vertical LEDs encounter challenges in electrically isolating the anode and cathode during the interconnection process. This requires depositing vertical insulators between the terminals in, for example, robotic assembly of LED displays. For example, if one terminal is on the bottom and one terminal is on the top, the terminals occupy the same space in the xy plane and require a robust insulator.

[0020] Additionally, the horizontal separation of the contact pads allows the connections to the terminals of each micro-LED to be formed on a single level, thereby reducing the number of levels in the display and improving placement accuracy. In certain embodiments, the micro-LEDs are assembled (e.g., via micro-transfer printing) onto an insulator, and holes are formed in the insulator to access the column lines underneath the insulator. Thus, this architecture reduces the number of levels required to form the display.

[0021] Furthermore, the horizontal separation of the contact pads on the micro-LEDs provides benefits not available from a vertical LED structure. For example, a display using a vertical LED structure requires panel-level vertical electrical isolation between the two terminals (contact pads) of the LED. In contrast, in certain embodiments, the disclosed technology avoids this problem by placing the terminals on the same face of the micro-LEDs. The horizontal separation of the LED contact pads facilitates electrical isolation by virtue of the horizontal separation of the conductors, thereby avoiding the vertical electrical isolation requirement.

[0022] In certain embodiments, the disclosed technology provides elongated micro-LEDs (e.g., rectangular LEDs with large aspect ratios) with horizontally separated contact pads. This configuration reduces the placement accuracy of display panel conductors required to assemble the micro-LEDs to the display panel. In addition, fine lithography during LED construction can be used to minimize the separation distance between the terminals and other elements in the LED structure (e.g., a separation distance of 100 nm to 200 microns), thus increasing the possible size of the micro-LED terminals. Reducing the lateral separation between the terminals and LED structural elements, increasing the size of the terminals (within the constraints of the size of the LED), and horizontally separating the terminals increases the manufacturing tolerance for alignment and lithography errors between the assembled micro-LEDs and the relatively thick conductive lines used to interconnect the assembled micro-LEDs on the display substrate.

[0023] Furthermore, stacked transparent (or semi-transparent) displays are described herein that allow for tunable brightness, defect compensation, increased clarity, and / or 2.5D or 3D viewing.

[0024] Also described herein are displays formed from multiple integrated displays occupying the same viewing area as independent driver chips, displays with complementary RGB inorganic micro-LEDs, multi-mode displays with reflective display elements and micro-LED emitters in the same pixel, displays with pixels including yellow micro-LEDs (and / or other non-traditional RGB colors such as cyan) for more visually perfect devices, and micro-assembled micro-LED displays with, for example, up to 9 micro-LEDs per pixel. The disclosed techniques also facilitate photoluminescence or functional testing of micro-assembled micro-LEDs.

[0025] In certain embodiments, the disclosed technology utilizes micro-transfer printing techniques to form imaging devices, such as micro-LED display devices. For example, in certain embodiments, electronic active components are transferred from homogeneous substrates (e.g., inorganic semiconductor materials, single crystal silicon wafers, silicon-on-insulator wafers, polycrystalline silicon wafers, and GaAs wafers, Si (1 1 1), GaN, sapphire, InP, InAlP, InGaAs, AlGaAs, GaSb, GaAlSb, AlSb, InSb, InGaAlSbAs, InAlSb, and InGaP) to display substrates (e.g., non-homogeneous substrates such as glass, plastic, or metal for forming arrays of active components on non-homogeneous substrates, for example). In some embodiments, the transfer is performed using an elastomeric stamp and / or an electrostatic stamp. The release of the active components is controlled and predictable, thereby enabling the production of the micro-LED displays described herein using micro-transfer printing techniques.

[0026] For example, a microstructure stamp, such as an elastomeric stamp or an electrostatic stamp (or other transfer device), can be used to pick up micro devices (e.g., micro LEDs, sensors, or integrated circuits), transport the micro devices to a destination display substrate, and print the micro devices onto the display substrate. Surface adhesion can be used to control the selection of these devices and print them onto the display substrate. This process can be performed in massively parallel, transferring hundreds to thousands of discrete structures in a single pick and print operation.

[0027] In one aspect, the present invention is directed to an inorganic light emitting diode display, comprising: a plurality of inorganic light emitting diodes assembled into an array on a display substrate that is non-homogeneous to the plurality of light emitting diodes, wherein each light emitting diode in the array comprises a first metal terminal on a first side of the corresponding light emitting diode, the first metal terminal being horizontally separated from a second metal terminal on the first side of the same light emitting diode by a horizontal distance, wherein the horizontal distance is from 100 nm to 20 microns.

[0028] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each of the plurality of light emitters has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each of the plurality of light emitters has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In certain embodiments, each of the plurality of light emitters has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0029] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0030] In certain embodiments, each light-emitting diode includes: a conductive layer; and an inorganic light-emitting layer disposed on a portion of the conductive layer, the conductive layer including a cantilever extension extending beyond an edge of the inorganic light-emitting layer, wherein the first metal terminal is disposed on a portion of the inorganic light-emitting layer and the second metal terminal is disposed on the cantilever extension of the conductive layer, wherein an electric current supplied between the first metal terminal and the second metal terminal causes the inorganic light-emitting layer to emit light.

[0031] In certain embodiments, the lateral conductive layer includes at least one component selected from the group consisting of: a metal mirror, a dielectric mirror, a high refractive index semiconductor, and a semiconductor substantially transparent to the light emitted from the light emitting diode, thereby forming an upward emitting display.

[0032] In certain embodiments, the lateral conductive layer includes at least one component selected from the group consisting of: a semiconductor substantially transparent to the light emitted from the LED, a transparent conductive oxide, and a thin metal mesh.

[0033] In some embodiments, the first metal terminal and the second metal terminal are transparent. In some embodiments, the first metal terminal and the second metal terminal include at least one member selected from the group consisting of: ITO, ZnO, carbon nanotube film, aluminum, silver, gold, nickel, platinum, titanium, and fine metal mesh.

[0034] In certain embodiments, the display is a downward emitting micro-LED display such that a majority of the light emitted by the plurality of light emitting diodes is emitted through the display substrate.

[0035] In some embodiments, the display includes a plurality of optical reflective structures, each optical reflective structure being located on a same side of a corresponding light emitting diode of the plurality of light emitting diodes as the first metal terminal.

[0036] In certain embodiments, the first and second metal terminals are at least partially reflective, thereby allowing light emitted from the corresponding light-emitting diodes to be at least partially reflected from the first and second metal terminals and pass through a second side of each light-emitting diode opposite the first side.

[0037] In some embodiments, the material directly underlying at least a portion of each light emitting diode is at least partially transparent.

[0038] In certain embodiments, the display is an upward emitting micro-LED display such that a majority of the light emitted by the plurality of light emitting diodes is emitted in a direction away from the display substrate.

[0039] In some embodiments, the display includes a plurality of optical reflective structures, each optical reflective structure being located below a corresponding light-emitting diode of the plurality of light-emitting diodes on a side of the light-emitting diode opposite the first metal terminal.

[0040] In certain embodiments, the first metal terminal and the second metal terminal are at least partially transparent, thereby allowing light emitted from a corresponding light emitting diode to at least partially pass through the first metal terminal and the second metal terminal.

[0041] In some embodiments, the display includes: a plurality of first interconnects, each first interconnect electrically connected to the first metal terminal of a corresponding light-emitting diode; and a plurality of second interconnects, each second interconnect electrically connected to the second metal terminal of a corresponding light-emitting diode, wherein the plurality of first interconnects and the plurality of second interconnects are located on the first surface.

[0042] In certain embodiments, the first plurality of interconnect features and the second plurality of interconnect features are in a single lithographic level.

[0043] In certain embodiments, each of the plurality of first interconnects is electrically coupled to one of the plurality of column electrodes through a via of a plurality of vias in the insulator, each via being associated with one of the plurality of light emitting diodes.

[0044] In some embodiments, the plurality of column electrodes, the plurality of first interconnects, and the plurality of second interconnects are formed by photolithography having a coarser resolution than photolithography used to form the first metal terminal and the second metal terminal.

[0045] In some embodiments, each of the light emitting diodes has a length greater than or equal to twice its width. In some embodiments, for each of the plurality of light emitting diodes, the corresponding first metal terminal and the corresponding second metal terminal cover at least half, two-thirds, or three-quarters of a lateral footprint of the corresponding light emitting diode. In some embodiments, the plurality of light emitting diodes are assembled via micro transfer printing.

[0046] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0047] In some embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light. In some embodiments, the display substrate has a continuous display substrate area including the plurality of light emitting diodes, each of the plurality of light emitting diodes having a light emitting area, and the combined light emitting area of ​​the plurality of light emitting diodes is less than or equal to one quarter of the continuous display substrate area.

[0048] In some embodiments, the combined light emitting area of ​​the plurality of LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0049] In some embodiments, for each of the plurality of inorganic light emitting diodes, the horizontal distance is from 500 nm to 1 μm, from 1 μm to 5 μm, from 5 μm to 10 μm, or from 10 μm to 20 μm. In some embodiments, for each of the plurality of inorganic light emitting diodes, a surface of the first metal terminal shares a plane with a surface of the second metal terminal.

[0050] In some embodiments, the display includes: a plurality of micro-integrated circuits located on the display substrate, each micro-integrated circuit being electrically connected to a group of light-emitting diodes among the plurality of light-emitting diodes.

[0051] In certain embodiments, each integrated circuit is used to control an LED that emits a specific color of light.

[0052] In some embodiments, each group of light emitting diodes in the plurality of light emitting diodes driven by a corresponding integrated circuit forms an independent sub-display.

[0053] In certain embodiments, the display includes: a plurality of second inorganic light-emitting diodes assembled into a second array on a second display substrate that is non-homogeneous to the plurality of second light-emitting diodes, wherein each of the plurality of second light-emitting diodes includes a first metal terminal on a first side of the corresponding light-emitting diode, the first metal terminal being horizontally separated from a second metal terminal on the first side of the same light-emitting diode by a horizontal distance, wherein the horizontal distance is from 100 nm to 20 microns, and wherein the first display substrate and the second substrate are stacked.

[0054] In certain embodiments, the display includes: a plurality of second inorganic light-emitting diodes assembled into a second array on a side of the display substrate opposite to the plurality of inorganic light-emitting diodes, wherein each of the plurality of second light-emitting diodes includes a first metal terminal on a first side of the corresponding light-emitting diode, the first metal terminal being horizontally separated from a second metal terminal on the first side of the same light-emitting diode by a horizontal distance, wherein the horizontal distance is from 100 nm to 20 microns, wherein the first display substrate and the second substrate are stacked.

[0055] In certain embodiments, the array of the plurality of inorganic light emitting diodes has a different resolution than the second array of the second plurality of inorganic light emitting diodes.

[0056] In certain embodiments, each of the plurality of inorganic light emitting diodes has a first size, each of the plurality of second inorganic light emitting diodes has a second size, and the first size is different from the second size.

[0057] In another aspect, the present invention is directed to a method for forming an LED display, the method comprising: forming a plurality of column lines on a substrate; depositing an insulator on the column lines; micro-transfer printing a plurality of LEDs onto the insulator, wherein each micro-LED comprises a first metal terminal and a second metal terminal on a first surface of the LED, wherein the substrate is non-homogeneous to the plurality of LEDs; forming a plurality of holes in the insulator to expose a portion of each of the plurality of column lines; and depositing a plurality of conductive interconnects on the first surface, the plurality of conductive interconnects comprising a plurality of row electrodes and a plurality of column interconnects, wherein each of the plurality of column interconnects electrically connects a column line to the first metal terminal of a corresponding LED.

[0058] In some embodiments, for each light emitting diode of the plurality of light emitting diodes, the first metal terminal is horizontally separated from the second metal terminal on the first face of the same light emitting diode by a horizontal distance from 100 nm to 5 microns.

[0059] In some embodiments, the first metal terminal and the second metal terminal are transparent. In some embodiments, the first metal terminal and the second metal terminal are at least partially transparent, thereby allowing light emitted from the corresponding light emitting diode to at least partially pass through the first metal terminal and the second metal terminal.

[0060] In certain embodiments, the display is a downward emitting micro-LED display such that a majority of the light emitted by the plurality of light emitting diodes is emitted through the display substrate.

[0061] In some embodiments, the method includes depositing a plurality of optically reflective structures, each optically reflective structure being located over a light emitting diode of the plurality of light emitting diodes on a side of the light emitting diode opposite the display substrate.

[0062] In some embodiments, the material directly underlying at least a portion of each light emitting diode is at least partially transparent.

[0063] In some embodiments, the first metal terminal and the second metal terminal are at least partially reflective, thereby allowing light emitted from the corresponding light-emitting diode to be at least partially reflected from the first metal terminal and the second metal terminal and pass through a second face of each light-emitting diode opposite to the first face. In some embodiments, the first metal terminal and the second metal terminal include at least one member selected from the group consisting of: ITO, ZnO, carbon nanotube film, aluminum, silver, gold, nickel, platinum, titanium, and fine metal mesh.

[0064] In certain embodiments, the display is an upward emitting micro-LED display such that a majority of the light emitted by the plurality of light emitting diodes is emitted in a direction away from the display substrate.

[0065] In certain embodiments, the method includes, prior to microtransfer printing the plurality of light emitting diodes, depositing a plurality of optically reflective structures, each optically reflective structure being located below a corresponding light emitting diode of the plurality of light emitting diodes.

[0066] In certain embodiments, each light-emitting diode includes: a conductive layer; and an inorganic light-emitting layer disposed on a portion of the conductive layer, the conductive layer including a cantilever extension extending beyond an edge of the inorganic light-emitting layer, wherein the first metal terminal is disposed on a portion of the inorganic light-emitting layer and the second metal terminal is disposed on the cantilever extension of the conductive layer, wherein an electric current supplied between the first metal terminal and the second metal terminal causes the inorganic light-emitting layer to emit light.

[0067] In certain embodiments, the lateral conductive layer includes at least one component selected from the group consisting of: a metal mirror, a dielectric mirror, a high refractive index semiconductor, and a semiconductor substantially transparent to the light emitted from the light emitting diode, thereby forming an upward emitting display.

[0068] In certain embodiments, the lateral conductive layer includes at least one component selected from the group consisting of: a semiconductor substantially transparent to the light emitted from the LED, a transparent conductive oxide, and a thin metal mesh.

[0069] In certain embodiments, micro-transfer printing the plurality of light-emitting diodes comprises: providing a transfer device to which a portion of the plurality of light-emitting diodes is removably attached, wherein the transfer device comprises a three-dimensional feature that is at least partially in contact with the portion of the plurality of light-emitting diodes; bringing the portion of the plurality of light-emitting diodes removably attached to the transfer device into contact with a receiving surface of the substrate; and separating the transfer device from the portion of the plurality of light-emitting diodes after the contact of the portion of the plurality of light-emitting diodes with the receiving surface, wherein the portion of the plurality of light-emitting diodes is transferred onto the receiving surface.

[0070] In some embodiments, the method includes: a plurality of column electrodes, each column electrode electrically connected to a corresponding one of a plurality of first interconnects; and an insulator interposed between the plurality of column electrodes and the plurality of light-emitting diodes, wherein a plurality of second interconnects include a plurality of row electrodes electrically connected to the second metal terminal of at least one of the plurality of light-emitting diodes.

[0071] In certain embodiments, each of the plurality of first interconnects is electrically coupled to one of the column electrodes of the plurality of column electrodes through a via of a plurality of vias in the insulator.

[0072] In some embodiments, the plurality of column electrodes, the plurality of first interconnects, and the plurality of second interconnects are formed by photolithography having a coarser resolution than photolithography used to form the first metal terminal and the second metal terminal.

[0073] In certain embodiments, the plurality of column electrodes, the plurality of first interconnects, and the plurality of second interconnects have a minimum line and space dimension ranging from 2 microns to 2 millimeters.

[0074] In certain embodiments, each of the light emitting diodes has a length greater than or equal to twice its width.

[0075] In certain embodiments, the first plurality of interconnect features and the second plurality of interconnect features are in a single lithographic level.

[0076] In some embodiments, for each light emitting diode of the plurality of light emitting diodes, the corresponding first metal terminal and the corresponding second metal terminal cover at least half, two thirds, or three quarters of a lateral occupied area of ​​the corresponding light emitting diode.

[0077] In certain embodiments, the first face of each of the plurality of light emitting diodes is located on a side of each diode that is distal from the display substrate.

[0078] In certain embodiments, the non-homogeneous substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0079] In some embodiments, each of the plurality of light emitting diodes has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each of the plurality of light emitting diodes has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each of the plurality of light emitting diodes has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0080] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0081] In some embodiments, the display substrate has a continuous display substrate area including a plurality of LEDs, each of the plurality of LEDs having a light emitting area, and a combined light emitting area of ​​the plurality of LEDs is less than or equal to one quarter of the continuous display substrate area.

[0082] In some embodiments, the combined light emitting area of ​​the light emitters is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten thousandth of the continuous display substrate area.

[0083] In certain embodiments, the plurality of conductive interconnects are deposited in a single step.

[0084] In some embodiments, the method includes: micro-transfer printing a plurality of micro-integrated circuits on the display substrate, each micro-integrated circuit being electrically connected to a group of light emitting diodes in the plurality of light emitting diodes. In some embodiments, each integrated circuit is used to control an LED that emits light of a specific color.

[0085] In certain embodiments, the method includes: micro-transfer printing a plurality of second inorganic light-emitting diodes into a second array on a second display substrate that is not homogeneous to the plurality of second light-emitting diodes, wherein each of the plurality of second light-emitting diodes includes a first metal terminal on a first side of the corresponding light-emitting diode, and the first metal terminal is horizontally separated from the second metal terminal on the first side of the same light-emitting diode by a horizontal distance, wherein the horizontal distance is from 100 nm to 20 microns, and wherein the first display substrate and the second substrate are stacked.

[0086] In certain embodiments, the method includes: micro-transfer printing a plurality of second inorganic light-emitting diodes into a second array on a side of the display substrate opposite to the plurality of inorganic light-emitting diodes, wherein each of the plurality of second light-emitting diodes includes a first metal terminal on a first side of the corresponding light-emitting diode, and the first metal terminal is horizontally separated from a second metal terminal on the first side of the same light-emitting diode by a horizontal distance, wherein the horizontal distance is from 100 nm to 20 microns, and wherein the first display substrate and the second substrate are stacked.

[0087] In certain embodiments, the array of the plurality of inorganic light emitting diodes has a different resolution than the second array of the second plurality of inorganic light emitting diodes.

[0088] In certain embodiments, each of the plurality of inorganic light emitting diodes has a first size, each of the plurality of second inorganic light emitting diodes has a second size, and the first size is different from the second size.

[0089] In another aspect, the present invention is directed to a display comprising: a display substrate; a first patterned metal layer located on a surface of the display substrate; a dielectric layer located on the display substrate and the first patterned metal layer; a polymer layer located on the dielectric layer; a plurality of light emitters located on the surface of the polymer layer, each of the plurality of light emitters having an anode and a cathode on the same side of the corresponding light emitter, wherein the display substrate is non-homogeneous to the plurality of light emitters; a plurality of through holes formed through the polymer layer and the dielectric layer, each through hole being associated with a corresponding light emitter among the plurality of light emitters; and a second patterned metal layer, the second patterned metal layer comprising a plurality of anode interconnects and a plurality of cathode interconnects in a single layer, each anode interconnect electrically connecting the anode of a corresponding light emitter among the plurality of light emitters to the first patterned metal layer through a corresponding through hole among the plurality of through holes and each cathode interconnect electrically contacting the cathode of a corresponding light emitter among the plurality of light emitters.

[0090] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0091] In certain embodiments, the plurality of light emitters comprises a plurality of inorganic light emitting diodes.

[0092] In some embodiments, the display substrate has a thickness from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm.

[0093] In some embodiments, each of the plurality of light emitters has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each of the plurality of light emitters has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each of the plurality of light emitters has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0094] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0095] In certain embodiments, the display substrate has a continuous display substrate area, the plurality of light emitters each have a light emitting area, and the combined light emitting area of ​​the plurality of light emitters is less than or equal to one quarter of the continuous display substrate area.

[0096] In some embodiments, the combined light emitting area of ​​the multiple light emitters is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0097] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0098] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0099] In some embodiments, the first patterned metal layer includes a metal stack. In some embodiments, the metal stack includes aluminum and titanium. In some embodiments, the titanium is located on the aluminum.

[0100] In certain embodiments, the polymer layer is a photosensitive negative-acting semiconductor grade epoxy.

[0101] In certain embodiments, the plurality of light emitters have been micro transfer printed on the surface of the polymer layer using a printing tool.

[0102] In certain embodiments, the printing tool is a viscoelastic elastomeric stamp.

[0103] In some embodiments, the second patterned metal layer comprises a metal stack. In some embodiments, the metal stack comprises Ti / Al / Ti.

[0104] In certain embodiments, the second patterned metal layer includes a plurality of pads on the display substrate.

[0105] In some embodiments, the plurality of light emitters include a plurality of red light emitters emitting red light, a plurality of green light emitters emitting green light, and a plurality of blue light emitters emitting blue light.

[0106] In certain embodiments, at least one of the anode and cathode of each light emitter of the plurality of light emitters is formed on a light emitter dielectric layer.

[0107] In certain embodiments, the dielectric layer is silicon nitride.

[0108] In certain embodiments, the display substrate is flexible.

[0109] In another aspect, the present invention is directed to a method of forming a display, the method comprising: depositing a first metal layer on a display substrate; patterning the first metal layer to form a first patterned metal layer; depositing a dielectric layer onto the first patterned metal layer to form an electrical insulating layer; applying an uncured polymer layer; micro-transfer printing a plurality of light emitters from a homogeneous substrate onto the polymer, wherein the homogeneous substrate is homogeneous to at least a portion of the plurality of light emitters and the light emitters each have an anode and a cathode for providing power to the light emitters; exposing the polymer to ultraviolet light to cure the polymer; and The invention relates to a method for forming a second patterned metal layer, wherein the second metal layer and the dielectric layer form a plurality of through holes to expose a portion of the first patterned metal layer; depositing a second metal layer, wherein the second metal layer contacts the anode and the cathode of each of the plurality of light emitters; and patterning the second metal layer to form a second patterned metal layer, wherein the second patterned metal layer includes a plurality of anode interconnects and a plurality of cathode interconnects, each anode interconnect electrically connecting the anode of a corresponding light emitter of the plurality of light emitters to the first patterned metal layer through a corresponding through hole in the plurality of through holes, and each cathode interconnect electrically contacting the cathode of a corresponding light emitter of the plurality of light emitters.

[0110] In certain embodiments, the plurality of light emitters comprises a plurality of inorganic light emitting diodes.

[0111] In some embodiments, the method includes cutting the display substrate into a plurality of displays.

[0112] In certain embodiments, the method includes: coating the non-homogeneous wafer with a protective photoresist layer before cutting the display substrate into the plurality of displays; and removing the protective photoresist layer from each of the plurality of displays after cutting the display substrate into the plurality of displays.

[0113] In certain embodiments, the method includes providing a passive matrix driver integrated circuit on a receiving pad on a surface of the non-homogeneous wafer.

[0114] In certain embodiments, the method includes burning in each light emitter of the plurality of light emitters.

[0115] In certain embodiments, the anode and cathode of a corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is 100 nm to 100 microns.

[0116] In certain embodiments, the polymer is a photosensitive negative-acting semiconductor grade epoxy.

[0117] In some embodiments, the first metal layer is deposited using metal physical vapor deposition. In some embodiments, the first metal layer is patterned using photolithography.

[0118] In some embodiments, patterning the first metal layer includes: before depositing the first metal layer, applying a negative-acting photoresist to the first metal layer, selectively exposing the photoresist to light (for example, using a mask), and developing the photoresist to form a stripping template; and after depositing the first metal layer, removing the stripping template, thereby forming the first patterned metal layer.

[0119] In certain embodiments, the first metal layer includes a metal stack of titanium-aluminum-titanium.

[0120] In some embodiments, depositing the first metal layer includes depositing the first metal layer using electron beam evaporation.

[0121] In certain embodiments, patterning the second metal layer includes: patterning a lift-off mask in a negative-acting photoresist; depositing a metal stack; and stripping the photoresist mask to leave the second patterned metal layer.

[0122] In certain embodiments, the second patterned metal layer includes a metal stack.

[0123] In certain embodiments, the metal stack includes Ti / Al / Ti.

[0124] In certain embodiments, the method includes removing one or more solvents from the polymer using one or more thermal treatments.

[0125] In certain embodiments, micro transfer printing the plurality of light emitters includes micro transfer printing the plurality of light emitters using a printing tool.

[0126] In certain embodiments, the printing tool comprises a viscoelastic elastomeric stamp.

[0127] In certain embodiments, microtransfer printing the plurality of light emitters includes using kinematically tunable adhesion between the plurality of light emitters and a viscoelastic elastomeric surface.

[0128] In certain embodiments, micro-transfer printing the plurality of light emitters includes: picking up at least a portion of the plurality of light emitters from the homogeneous substrate by: contacting a viscoelastic elastomeric stamp to a first surface of each of the portion of the plurality of light emitters; and moving the viscoelastic elastomeric stamp away from the homogeneous substrate at a first rate, the first rate resulting in an effective increase in adhesion between the elastomer and the portion of the plurality of light emitters; and printing the portion of the plurality of light emitters to the non-homogeneous substrate by: contacting a second surface of each of the light emitters picked up by the viscoelastic elastomeric stamp to the polymer; and moving the viscoelastic elastomeric stamp away from the display substrate at a second rate, thereby leaving the light emitters picked up by the viscoelastic elastomeric stamp on the polymer, wherein the second rate is less than the first rate.

[0129] In certain embodiments, the method includes moving the stamp in lateral shear during the microtransfer printing process.

[0130] In some embodiments, the plurality of light emitters include a plurality of red light emitters emitting red light, a plurality of green light emitters emitting green light, and a plurality of blue light emitters emitting blue light.

[0131] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0132] In certain embodiments, microtransfer printing the plurality of light emitters from a homogeneous substrate onto the polymer includes performing at least two microtransfer printing operations.

[0133] In certain embodiments, micro-transfer printing the multiple light emitters from a homogeneous substrate onto the polymer includes: micro-transfer printing a plurality of red light emitters emitting red light from a homogeneous substrate of red light emitters; micro-transfer printing a plurality of green light emitters emitting green light from a homogeneous substrate of green light emitters; and micro-transfer printing a plurality of blue light emitters emitting blue light from a homogeneous substrate of blue light emitters, wherein the multiple light emitters include the multiple red light emitters, the multiple green light emitters, and the multiple blue light emitters.

[0134] In certain embodiments, the display substrate is flexible.

[0135] In another aspect, the present invention is directed to an inorganic light emitting diode, comprising a conductive layer; an inorganic light emitting layer disposed on a portion of the conductive layer, the conductive layer comprising a cantilever extension extending beyond an edge of the inorganic light emitting layer; a first metal terminal disposed on a portion of the inorganic light emitting layer; a second metal terminal disposed on the cantilever extension of the conductive layer, wherein a current supplied between the first metal terminal and the second metal terminal causes the inorganic light emitting layer to emit light; and a dielectric layer disposed on at least a portion of the inorganic light emitting layer, wherein the dielectric layer electrically isolates the first metal terminal from the second metal terminal, wherein the first metal terminal and the second metal terminal are located on the same side of the inorganic light emitting diode and are separated by a horizontal distance from 100 nm to 20 μm.

[0136] In some embodiments, the inorganic light emitting diode has a width from 0.5 μm to 2 μm, from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, the inorganic light emitting diode has a length from 0.5 μm to 2 μm, from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, the inorganic light emitting diode has a height from 0.5 μm to 2 μm, from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, the horizontal distance is from 500 nm to 1 μm, from 1 μm to 5 μm, from 5 μm to 10 μm, or from 10 μm to 20 μm.

[0137] In some embodiments, a surface of the first metal terminal and a surface of the second metal terminal share a common plane.

[0138] In some embodiments, for each light emitting diode of the plurality of light emitting diodes, the corresponding first metal terminal and the corresponding second metal terminal cover at least half, two thirds, or three quarters of a lateral occupied area of ​​the corresponding light emitting diode.

[0139] In some embodiments, the lateral conductive layer comprises at least one component selected from the group consisting of: a metal mirror, a dielectric mirror, a high refractive index semiconductor, and a semiconductor substantially transparent to the light emitted from the light emitting diode, thereby forming an upward emitting display. In some embodiments, the lateral conductive layer comprises at least one component selected from the group consisting of: a semiconductor substantially transparent to the light emitted from the LED, a transparent conductive oxide, and a thin metal mesh.

[0140] In some embodiments, the first metal terminal and the second metal terminal are transparent. In some embodiments, the first metal terminal and the second metal terminal include at least one member selected from the group consisting of: ITO, ZnO, carbon nanotube film, aluminum, silver, gold, nickel, platinum, titanium, and fine metal mesh.

[0141] In another aspect, the present invention is directed to an inorganic light emitting diode display including a plurality of inorganic light emitting diodes, wherein the plurality of inorganic light emitting diodes are disposed on a substrate.

[0142] In some embodiments, the display substrate has a thickness from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm.

[0143] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0144] In some embodiments, the display further includes a plurality of optical reflective structures, each optical reflective structure being located on a same side of a corresponding light emitting diode among the plurality of light emitting diodes as the first metal terminal.

[0145] In some embodiments, the display further includes a plurality of optical reflective structures, each optical reflective structure being located below a corresponding light emitting diode of the plurality of light emitting diodes on a side of the light emitting diode opposite the first metal terminal.

[0146] In some embodiments, the display further includes: a plurality of first interconnects, each first interconnect electrically connected to the first metal terminal of a corresponding light-emitting diode; and a plurality of second interconnects, each second interconnect electrically connected to the second metal terminal of a corresponding light-emitting diode, wherein the plurality of first interconnects and the plurality of second interconnects are located on a first surface.

[0147] In certain embodiments, the first plurality of interconnect features and the second plurality of interconnect features are in a single lithographic level.

[0148] In certain embodiments, each of the plurality of first interconnects is electrically coupled to one of the plurality of column electrodes through a via of a plurality of vias in the insulator, each via being associated with one of the plurality of light emitting diodes.

[0149] In some embodiments, the plurality of column electrodes, the plurality of first interconnects, and the plurality of second interconnects are formed by photolithography having a coarser resolution than photolithography used to form the first metal terminal and the second metal terminal.

[0150] In certain embodiments, each of the light emitting diodes has a length greater than or equal to twice its width.

[0151] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0152] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0153] In some embodiments, the display substrate has a continuous display substrate area including the plurality of LEDs, each of the plurality of LEDs having a light emitting area, and the combined light emitting area of ​​the plurality of LEDs is less than or equal to one quarter of the continuous display substrate area.

[0154] In some embodiments, the combined light emitting area of ​​the plurality of LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0155] In another aspect, the present invention is directed to an inorganic light emitting diode (LED) display, comprising: a display substrate; a plurality of pixels, each pixel comprising a group of main inorganic LEDs connected to a display circuit and a group of redundant inorganic LEDs not connected to the display circuit, wherein each of the redundant inorganic LEDs can be electrically connected to the display circuit to replace a corresponding defective LED which is one of the main inorganic LEDs, wherein: each main and redundant inorganic LED is formed in or on a homogeneous substrate that is different and separate from the display substrate; and the homogeneous substrate is located on the display substrate.

[0156] In some embodiments, the display includes redundant LEDs electrically connected to the display circuitry.

[0157] In certain embodiments, the display includes conductive jumpers that electrically connect redundant LEDs to the display circuitry.

[0158] In another aspect, the present invention is directed to an inorganic light emitting diode (LED) display, comprising: a display substrate; a plurality of pixels, each pixel comprising a group of main inorganic LEDs and a group of redundant inorganic LEDs, wherein: each main and redundant inorganic LED is formed in or on a homogeneous substrate that is different and separate from the display substrate; the homogeneous substrate is located on the display substrate; and each inorganic LED in the redundant group is connected in series with a resistor to form an LED-resistor pair, and each LED-resistor pair is wired in parallel with the inorganic LED in the main group.

[0159] In another aspect, the present invention is directed to an inorganic light emitting diode (LED) display, comprising: a display substrate; a plurality of pixels, each pixel comprising a group of main inorganic LEDs and a group of redundant inorganic LEDs, wherein: each main and redundant inorganic LED is formed in or on a homogeneous substrate that is different and separate from the display substrate; the homogeneous substrate is located on the display substrate; and each inorganic LED in the redundant group is connected in series with a diode to form an LED-diode pair, and each LED-diode pair is wired in parallel with the inorganic LED in the main group.

[0160] In some embodiments, the group of main inorganic LEDs includes a plurality of red inorganic LEDs emitting red light, a plurality of green inorganic LEDs emitting green light, and a plurality of blue inorganic LEDs emitting blue light, and the group of redundant inorganic LEDs includes a plurality of redundant red inorganic LEDs emitting red light, a plurality of redundant green inorganic LEDs emitting green light, and a plurality of redundant blue inorganic LEDs emitting blue light.

[0161] In certain embodiments, the set of primary inorganic LEDs includes a plurality of yellow inorganic LEDs that emit yellow light; and the set of redundant inorganic LEDs includes a plurality of redundant yellow inorganic LEDs that emit yellow light.

[0162] In certain embodiments, the set of primary inorganic LEDs and the set of redundant inorganic LEDs are located directly on the display substrate.

[0163] In certain embodiments, each pixel includes an inorganic integrated circuit electrically connected to each inorganic LED in the corresponding pixel.

[0164] In some embodiments, each pixel includes a primary micro-integrated circuit and a redundant micro-integrated circuit.

[0165] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0166] In some embodiments, each inorganic LED has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each inorganic LED has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each inorganic LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0167] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0168] In certain embodiments, the display substrate has a continuous display substrate area including the set of primary inorganic LEDs and the set of redundant inorganic LEDs, each LED having a light emitting area, and the combined light emitting area of ​​the LEDs is less than or equal to one quarter of the continuous display substrate area.

[0169] In some embodiments, the combined light emitting area of ​​the LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0170] In another aspect, the present invention is directed to a method of inorganically assembling an inorganic light emitting diode (LED) display, the method comprising: forming a plurality of printable inorganic LEDs in or on one or more homogeneous substrates; transfer printing the plurality of printable inorganic LEDs onto a display substrate separate and different from the one or more homogeneous substrates to form a plurality of pixels, wherein each pixel comprises a group of main inorganic LEDs and a group of redundant inorganic LEDs; connecting the main inorganic LEDs to a display circuit; and testing the display to identify defective main inorganic LEDs.

[0171] In some embodiments, the group of main inorganic LEDs includes a plurality of red inorganic LEDs emitting red light, a plurality of green inorganic LEDs emitting green light, and a plurality of blue inorganic LEDs emitting blue light, and the group of redundant inorganic LEDs includes a plurality of redundant red inorganic LEDs emitting red light, a plurality of redundant green inorganic LEDs emitting green light, and a plurality of redundant blue inorganic LEDs emitting blue light.

[0172] In certain embodiments, the set of primary inorganic LEDs includes a plurality of yellow inorganic LEDs that emit yellow light; and the set of redundant inorganic LEDs includes a plurality of redundant yellow inorganic LEDs that emit yellow light.

[0173] In certain embodiments, the method includes disconnecting the defective primarily inorganic LED from the display circuitry.

[0174] In certain embodiments, the method includes establishing an electrical connection to a redundant inorganic LED in close proximity to each of the defective primary inorganic LEDs such that each of the redundant inorganic LEDs is connected to the display circuit.

[0175] In certain embodiments, establishing an electrical connection to each of the redundant LEDs includes directly and physically writing an electrical trace.

[0176] In some embodiments, establishing electrical connections to each of the redundant LEDs includes placing conductive jumpers between each of the redundant LEDs and the corresponding defective LEDs by microassembly. In some embodiments, establishing electrical connections to each of the redundant LEDs includes establishing electrical connections by solder reflow or contacts between clean metal surfaces.

[0177] In certain embodiments, the method includes, prior to testing the display, connecting each redundant inorganic LED in series with a resistor to the display circuit to form an LED-resistor pair such that each LED-resistor pair is connected in parallel with a primary inorganic LED.

[0178] In certain embodiments, the method includes, prior to testing the display, connecting each redundant inorganic LED and diode in series to the display circuit to form an LED-diode pair such that each LED-diode pair is connected in parallel with a primary inorganic LED.

[0179] In certain embodiments, testing the display includes: illuminating one or more of the primary inorganic LEDs; and identifying a defective primary LED.

[0180] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0181] In certain embodiments, the plurality of printable inorganic LEDs are micro-transfer printed directly onto the display substrate.

[0182] In some embodiments, each inorganic LED has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each inorganic LED has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each inorganic LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0183] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0184] In certain embodiments, the display substrate has a continuous display substrate area including the set of primary inorganic LEDs and the set of redundant inorganic LEDs, each LED having a light emitting area, and the combined light emitting area of ​​the LEDs is less than or equal to one quarter of the continuous display substrate area.

[0185] In some embodiments, the combined light emitting area of ​​the LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0186] In another aspect, the present invention is directed to a micro-LED display comprising: a display substrate that is at least partially transparent; an array of color conversion structures that are located on the display substrate, each color conversion structure comprising a color conversion material; and a micro-LED array that is separated from the color conversion structures, each micro-LED in the micro-LED array being located on a corresponding one of the color conversion structures in the array of color conversion structures.

[0187] In certain embodiments, the display substrate includes an array of recesses, the color converting material being located in the recesses.

[0188] In certain embodiments, the recess is filled with the color conversion material.

[0189] In certain embodiments, the micro-LEDs are located above the color converting material on a side of the color converting material opposite the display substrate such that most or all of the light emitted from the micro-LEDs is emitted downwardly through the color converting material and the display substrate.

[0190] In certain embodiments, the display includes one or more reflective structures that substantially cover a side of the micro-LEDs opposite the display substrate such that the micro-LEDs reflect emitted light toward the display substrate.

[0191] In certain embodiments, the one or more reflective structures include an array of connected metal or micro-LED contacts.

[0192] In another aspect, the present invention is directed to a micro-LED display comprising: a display substrate; a micro-LED array located on the display substrate; and an array of color conversion structures separated from the micro-LED structures, each color conversion structure in the array of color conversion structures being located on a corresponding one of the micro-LEDs in the micro-LED array, wherein each color conversion structure comprises a color conversion material.

[0193] In certain embodiments, the color conversion material is located on top of the micro-LED or at least partially surrounds the micro-LED on a side of the micro-LED opposite the display substrate.

[0194] In some embodiments, the color conversion material comprises a phosphor-containing gel or resin, a phosphor ceramic, or a single crystal phosphor. In some embodiments, the color conversion material is a chip of a direct bandgap semiconductor. In some embodiments, the color conversion material at least partially surrounds the micro-LED.

[0195] In certain embodiments, the display includes a supplemental mirror structure on the display substrate.

[0196] In certain embodiments, each micro-LED has an LED substrate separate from the display substrate.

[0197] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is distinct and separate from the display substrate.

[0198] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each micro-LED has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In certain embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0199] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0200] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0201] In certain embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED has a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0202] In some embodiments, the combined light emitting area of ​​the micro-LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0203] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0204] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0205] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0206] In some embodiments, the micro LED array includes a plurality of red micro LEDs emitting red light, a plurality of green micro LEDs emitting green light, and a plurality of blue micro LEDs emitting blue light, and each pixel includes a red micro LED from the plurality of red micro LEDs, a green micro LED from the plurality of green micro LEDs, and a blue micro LED from the plurality of blue micro LEDs.

[0207] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0208] In another aspect, the present invention is directed to a method of microassembling a micro-LED light emitter array, the method comprising: forming a plurality of micro-LEDs on a first substrate; providing a display substrate, the display substrate being at least partially transparent; providing a plurality of color conversion structures in an array on the display substrate, each color conversion structure comprising a color conversion material; microassembling the plurality of micro-LEDs onto the display substrate such that each of the plurality of micro-LEDs is located on a corresponding one of the color conversion structures of the plurality of color conversion structures, wherein microassembling the plurality of micro-LEDs onto the display substrate comprises: contacting a portion of the plurality of micro-LEDs with a first transfer device having a contact surface, thereby temporarily bonding the portion of the plurality of micro-LEDs to the contact surface such that the portion of the plurality of micro-LEDs is temporarily disposed on the contact surface; contacting the portion of the plurality of micro-LEDs disposed on the contact surface of the first transfer device with a portion of the plurality of color conversion structures; and separating the contact surface of the first transfer device from the portion of the plurality of micro-LEDs, wherein the portion of the plurality of micro-LEDs is transferred to the portion of the color conversion structure, thereby assembling the portion of the plurality of micro-LEDs on the portion of the color structure.

[0209] In some embodiments, providing a plurality of color conversion structures arrayed above the display substrate includes: before microassembling the plurality of micro-LEDs onto the display substrate: forming a plurality of recesses in the display substrate; and filling the plurality of recesses with a color conversion material, and printing a plurality of printable LEDs above the color conversion material.

[0210] In some embodiments, providing a plurality of color conversion structures in an array above the display substrate includes: prior to microassembling the plurality of micro-LEDs on the display substrate: microassembling chips of color conversion material on the display substrate.

[0211] In certain embodiments, the micro-LEDs are located above the color converting material on a side of the color converting material opposite the display substrate such that most or all of the light emitted from the micro-LEDs is emitted downwardly through the color converting material and the display substrate.

[0212] In certain embodiments, the method includes one or more reflective structures substantially covering a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate.

[0213] In certain embodiments, the one or more reflective structures include an array of connected metal or micro-LED contacts.

[0214] In another aspect, the present invention is directed to a method for microassembling a micro-LED light emitter array, the method comprising: forming a plurality of micro-LEDs on a first substrate; providing a display substrate; microassembling the plurality of micro-LEDs onto the display substrate, wherein microassembling the plurality of micro-LEDs onto the display substrate comprises: contacting a portion of the plurality of micro-LEDs with a first transfer device having a contact surface, thereby temporarily bonding the portion of the plurality of micro-LEDs to the contact surface such that the portion of the plurality of micro-LEDs is temporarily disposed on the contact surface; contacting the portion of the plurality of micro-LEDs disposed on the contact surface of the first transfer device with a portion of a plurality of color conversion structures; separating the contact surface of the first transfer device from the portion of the plurality of micro-LEDs, wherein the portion of the plurality of micro-LEDs is transferred onto the portion of the color conversion structure, thereby assembling the portion of the plurality of micro-LEDs onto the portion of the color conversion structure; and providing a plurality of color conversion structures in an array on the display substrate such that each of the plurality of color conversion structures is located on a corresponding one of the micro-LEDs of the plurality of micro-LEDs, wherein each color conversion structure comprises a color conversion material.

[0215] In certain embodiments, the color conversion material is located on top of the micro-LED or at least partially surrounds the micro-LED on a side of the micro-LED opposite the display substrate.

[0216] In some embodiments, the color conversion material comprises a phosphor-containing gel or resin, a phosphor ceramic, or a single crystal phosphor. In some embodiments, the color conversion material is a chip of a direct bandgap semiconductor. In some embodiments, the color conversion material at least partially surrounds the micro-LED.

[0217] In certain embodiments, the method includes supplementing a mirror structure on the display substrate.

[0218] In certain embodiments, each micro-LED has an LED substrate separate from the display substrate.

[0219] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is distinct and separate from the display substrate.

[0220] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each micro-LED has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In certain embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0221] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0222] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0223] In certain embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED has a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0224] In some embodiments, the combined light emitting area of ​​the micro-LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0225] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0226] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0227] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0228] In some embodiments, the plurality of micro-LEDs include a plurality of red micro-LEDs emitting red light, a plurality of green micro-LEDs emitting green light, and a plurality of blue micro-LEDs emitting blue light, and each pixel includes a red micro-LED among the plurality of red micro-LEDs, a green micro-LED among the plurality of green micro-LEDs, and a blue micro-LED among the plurality of blue micro-LEDs.

[0229] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0230] In another aspect, the present invention is directed to a multifunctional display comprising: a display substrate; a micro-LED array located on the display substrate; and an array of functional elements located on the display substrate, the micro-LEDs being interlaced between the functional elements, wherein the display substrate is not homogeneous with the micro-LEDs and the functional elements.

[0231] In some embodiments, the functional element is a sensor or a transceiver. In some embodiments, the functional element includes at least one component selected from the group consisting of: an image capture device, an optical sensor, a photodiode, an infrared sensor, a gesture sensor, a temperature sensor, a power harvesting device, a solar cell, a kinetic energy collection device, a piezoelectric device, a capacitor, an antenna, and a wireless transmitting device.

[0232] In some embodiments, the functional elements have a different spatial density over the display substrate than the micro-LEDs.

[0233] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is separate and distinct from the display substrate.

[0234] In some embodiments, the functional elements are formed in a homogenous substrate that is separate and distinct from the display substrate. In some embodiments, the number of functional elements is less than or equal to the number of micro-LEDs in the display. In some embodiments, the number of functional elements is less than or equal to one third of the number of micro-LEDs in the display.

[0235] In some embodiments, the display substrate has a thickness from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm.

[0236] In some embodiments, each micro-LED has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each functional element has at least one of a width, length, and height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0237] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0238] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0239] In certain embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED has a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0240] In some embodiments, the combined light emitting area of ​​the micro-LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0241] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0242] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0243] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0244] In some embodiments, the micro LED array and the functional element array are located on a common plane.

[0245] In some embodiments, the multifunctional display includes: a plurality of micro-integrated circuits, each micro-integrated circuit connected to at least one micro-LED in the micro-LED array and at least one functional element in the functional element array.

[0246] In some embodiments, the multifunctional display includes: a polymer layer located on the display substrate, wherein the micro LED array and the functional element array are located on the polymer layer so that the polymer layer is interposed between the display substrate and the micro LED array and the functional element array.

[0247] In certain embodiments, the multifunctional display includes: a first patterned metal layer located on the surface of the display substrate; a dielectric layer located on the display substrate and the first patterned metal layer, wherein the polymer layer is located on the display substrate; a plurality of through holes formed through the polymer layer and the dielectric layer, each through hole being associated with a corresponding micro-LED; and a second patterned metal layer, the second patterned metal layer including a plurality of anode interconnects and a plurality of cathode interconnects in a single layer, each anode interconnect electrically connecting the anode of the corresponding micro-LED to the first patterned metal layer through a corresponding through hole in the plurality of through holes and each cathode interconnect electrically contacting the cathode of the corresponding micro-LED.

[0248] In some embodiments, the multifunctional display includes: a plurality of pixels, each pixel including at least one micro-LED in the micro-LED array and at least one functional element in the functional element array.

[0249] In some embodiments, the micro LED array includes a plurality of red micro LEDs emitting red light, a plurality of green micro LEDs emitting green light, and a plurality of blue micro LEDs emitting blue light, and each pixel includes a red micro LED from the plurality of red micro LEDs, a green micro LED from the plurality of green micro LEDs, and a blue micro LED from the plurality of blue micro LEDs.

[0250] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0251] In another aspect, the present invention is directed to a method for microassembling a light emitting diode (LED) display interlaced with functional elements, the method comprising: forming a plurality of micro-LEDs on a first substrate; forming a plurality of functional elements on a second substrate; microassembling the plurality of micro-LEDs onto a display substrate that is not homogeneous to the plurality of micro-LEDs and the plurality of functional elements, wherein microassembling the plurality of micro-LEDs onto the display substrate comprises: contacting a portion of the plurality of micro-LEDs with a first transfer device having a contact surface, thereby temporarily bonding the portion of the plurality of micro-LEDs to the contact surface so that the portion of the plurality of micro-LEDs is temporarily disposed on the contact surface; contacting the portion of the plurality of micro-LEDs disposed on the contact surface of the first transfer device with a receiving surface of the display substrate; separating the contact surface of the first transfer device from the portion of the plurality of micro-LEDs, Wherein, part of the multiple micro-LEDs are transferred to the receiving surface, thereby assembling the part of the multiple micro-LEDs on the receiving surface of the display substrate; and the multiple functional elements are micro-assembled onto the display substrate, which includes: bringing a part of the multiple functional elements in the part of the multiple functional elements into contact with a second transfer device, thereby bonding the part of the multiple functional elements to a contact surface so that the part of the multiple functional elements is placed on the contact surface; bringing the part of the multiple functional elements placed on the contact surface of the second transfer device into contact with the receiving surface of the display substrate; and separating the contact surface of the second transfer device from the part of the multiple functional elements, wherein the part of the multiple functional elements are transferred to the receiving surface of the display substrate, thereby assembling the part of the multiple functional elements on the receiving surface of the display substrate.

[0252] In some embodiments, the plurality of functional elements are sensors or transceivers.

[0253] In some embodiments, the plurality of functional elements include at least one component selected from the group consisting of: an image capture device, an optical sensor, a photodiode, an infrared sensor, a gesture sensor, a temperature sensor, a power harvesting device, a solar cell, a kinetic energy collection device, a piezoelectric device, a capacitor, an antenna, and a wireless transmitting device.

[0254] In certain embodiments, the plurality of functional elements have a different spatial density over the display substrate than the micro-LEDs.

[0255] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is separate and distinct from the display substrate.

[0256] In certain embodiments, the plurality of functional elements are formed in a homogenous substrate that is separate and distinct from the display substrate.

[0257] In some embodiments, the number of functional elements is less than or equal to the number of micro-LEDs in the display.

[0258] In certain embodiments, the number of functional elements is less than or equal to one third of the number of micro-LEDs in the display.

[0259] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each micro-LED has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each functional element has at least one of a width, a length, and a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0260] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0261] In certain embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0262] In certain embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED has a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0263] In some embodiments, the combined light emitting area of ​​the plurality of LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0264] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0265] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0266] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0267] In some embodiments, the plurality of micro-LEDs and the plurality of functional elements are located on a common plane.

[0268] In some embodiments, the method includes a plurality of micro integrated circuits, each micro integrated circuit connected to at least one micro LED of the plurality of micro LEDs and at least one functional element of the plurality of functional elements.

[0269] In certain embodiments, the method includes a polymer layer located on the display substrate, wherein the plurality of micro-LEDs and the plurality of functional elements are located on the polymer layer such that the polymer layer is interposed between the display substrate and the plurality of micro-LEDs and the plurality of functional elements.

[0270] In certain embodiments, the method includes: a first patterned metal layer located on a surface of the display substrate; a dielectric layer located on the display substrate and the first patterned metal layer, wherein the polymer layer is located on the display substrate; a plurality of vias formed through the polymer layer and the dielectric layer, each via being associated with a corresponding micro-LED; and

[0271] A second patterned metal layer, the second patterned metal layer includes a plurality of anode interconnects and a plurality of cathode interconnects in a single layer, each anode interconnect electrically connecting the anode of a corresponding micro-LED to the first patterned metal layer through a corresponding through hole in the plurality of through holes, and each cathode interconnect electrically contacting the cathode of the corresponding micro-LED.

[0272] In some embodiments, the method includes: a plurality of pixels, each pixel including at least one micro-LED of the plurality of micro-LEDs and at least one functional element of the plurality of functional elements.

[0273] In some embodiments, the plurality of micro-LEDs include a plurality of red micro-LEDs emitting red light, a plurality of green micro-LEDs emitting green light, and a plurality of blue micro-LEDs emitting blue light, and each pixel includes a red micro-LED among the plurality of red micro-LEDs, a green micro-LED among the plurality of green micro-LEDs, and a blue micro-LED among the plurality of blue micro-LEDs.

[0274] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0275] In some embodiments, the second transfer device is the first transfer device.

[0276] In certain embodiments, the first transfer device comprises an elastomeric stamp.

[0277] In another aspect, the present invention is directed to a multi-mode display comprising: a display substrate; a first emissive inorganic micro-LED display formed above the display substrate; and a second display formed above the display substrate, the second display being of a different type than the first emissive micro-LED display.

[0278] In some embodiments, the second display is a non-emissive reflective display. In some embodiments, the second display is an electrophoretic or MEMs-based display.

[0279] In certain embodiments, the first display includes a plurality of first pixels and the second display includes a plurality of second pixels, wherein each of the plurality of first pixels is smaller than each of the plurality of second pixels.

[0280] In some embodiments, the multi-mode display includes a controller for switching between the first display and the second display.

[0281] In certain embodiments, the multi-mode display comprises a cellular telephone, a smart phone, or a tablet computing device.

[0282] In some embodiments, the first display and the second display are located over different portions of the display substrate.

[0283] In some embodiments, the first display and the second display are located over the same portion of the display substrate. In some embodiments, the first display is located on top of the second display on a side of the second display opposite the display substrate.

[0284] In some embodiments, the light control elements of the first display are interleaved with the light control elements of the second display on the display substrate.

[0285] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is distinct and separate from the display substrate.

[0286] In some embodiments, the first display and the second display are formed on the display substrate. In some embodiments, the first display is located on a first side of the display substrate and the second display is located on a second side of the display substrate opposite the first side.

[0287] In certain embodiments, the second display is on the display substrate and the first display is on a micro LED display substrate that is separate from and above the display substrate.

[0288] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each micro-LED has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In certain embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0289] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0290] In some embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light. In some embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED having a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0291] In some embodiments, the combined light emitting area of ​​the micro-LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0292] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0293] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0294] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0295] In some embodiments, the first emissive micro LED display includes a plurality of red micro LEDs emitting red light, a plurality of green micro LEDs emitting green light, and a plurality of blue micro LEDs emitting blue light, and each pixel of the first emissive micro LED display includes a red micro LED among the plurality of red micro LEDs, a green micro LED among the plurality of green micro LEDs, and a blue micro LED among the plurality of blue micro LEDs.

[0296] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0297] In certain embodiments, the first emissive inorganic micro LED display comprises a plurality of inorganic micro LEDs formed in an LED substrate separate and distinct from the display substrate and the second display is formed on or in the display substrate and is homogeneous with the display substrate, wherein the LED substrate is adhered to the display substrate.

[0298] In another aspect, the present invention is directed to a method for microassembling a micro-LED light emitter array, the method comprising: forming a plurality of micro-LEDs on a first substrate; providing a display substrate; microassembling the plurality of micro-LEDs above the display substrate, thereby forming a first emitting micro-LED display above the display substrate; and forming a second display above the display substrate, the second display being of a type different from the first emitting micro-LED display.

[0299] In certain embodiments, the second display is a non-emissive reflective display.

[0300] In certain embodiments, the second display is an electrophoretic or MEMs-based display.

[0301] In certain embodiments, the first display includes a plurality of first pixels and the second display includes a plurality of second pixels, wherein each of the plurality of first pixels is smaller than each of the plurality of second pixels.

[0302] In some embodiments, the method further includes a controller for switching between the first display and the second display.

[0303] In certain embodiments, the method further includes a cellular telephone, a smart phone, or a tablet computing device.

[0304] In some embodiments, the first display and the second display are located over different portions of the display substrate. In some embodiments, the first display and the second display are located over the same portion of the display substrate. In some embodiments, the first display is located on top of the second display on a side of the second display opposite the display substrate.

[0305] In some embodiments, the light control elements of the first display are interleaved with the light control elements of the second display on the display substrate.

[0306] In certain embodiments, the micro-LEDs are formed in a homogenous substrate that is distinct and separate from the display substrate.

[0307] In certain embodiments, the first display and the second display are formed on the display substrate.

[0308] In certain embodiments, the first display is located on a first side of the display substrate and the second display is located on a second side of the display substrate opposite the first side.

[0309] In certain embodiments, the second display is on the display substrate and the first display is on a micro LED display substrate that is separate from and above the display substrate.

[0310] In some embodiments, the display substrate has a thickness of from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm. In some embodiments, each micro-LED has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, each micro-LED has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In certain embodiments, each micro-LED has a height from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0311] In some embodiments, the resolution of the display is 120×90, 1440×1080, 1920×1080, 1280×720, 3840×2160, 7680×4320, or 15360×8640.

[0312] In some embodiments, the display substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light. In some embodiments, the display substrate has a continuous display substrate area including the micro-LEDs, each micro-LED having a light emitting area, and the combined light emitting area of ​​the micro-LEDs is less than or equal to one quarter of the continuous display substrate area.

[0313] In some embodiments, the combined light emitting area of ​​the micro-LEDs is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten-thousandth of the continuous display substrate area.

[0314] In certain embodiments, each micro-LED has an anode and a cathode on the same side of the respective micro-LED.

[0315] In certain embodiments, the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0316] In certain embodiments, the display substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0317] In some embodiments, the plurality of micro-LEDs include a plurality of red micro-LEDs emitting red light, a plurality of green micro-LEDs emitting green light, and a plurality of blue micro-LEDs emitting blue light, and each pixel includes a red micro-LED among the plurality of red micro-LEDs, a green micro-LED among the plurality of green micro-LEDs, and a blue micro-LED among the plurality of blue micro-LEDs.

[0318] In certain embodiments, the micro-LEDs are organic micro-LEDs.

[0319] In another aspect, the present invention is directed to a microassembled device comprising: a device substrate; a first electrical conductor located on the device substrate; a second electrical conductor located on the device substrate; a conductive jumper element that is different and separate from the device substrate and has one or more jumper conductors; and wherein the conductive jumper element is located on the device substrate, wherein a first jumper conductor among the one or more jumper conductors is in electrical contact with the first electrical conductor and the second electrical conductor.

[0320] In certain embodiments, the conductive jumper element is a conductive passive device.

[0321] In some embodiments, the conductive jumper element is an active device. In some embodiments, the active device is a CMOS device. In some embodiments, the active device includes at least one of a drive circuit and a non-volatile memory.

[0322] In some embodiments, the conductive jumper element is housed in a structure suitable for micro-transfer printing. In some embodiments, the conductive jumper element comprises one or more of a semiconductor, silicon, silicon-on-insulator, glass, metal, and a dielectric.

[0323] In certain embodiments, the jumper conductor includes a semiconductor, a metal, a precious metal, gold, silver, platinum, copper, stainless steel, nickel, chromium, solder, PbSn, or AgSn.

[0324] In certain embodiments, a portion of the conductive jumper element adjacent to the conductor substrate is recessed.

[0325] In certain embodiments, the device includes a third electrical conductor on the conductor substrate that is electrically isolated from the first electrical conductor and the second electrical conductor, wherein the third electrical conductor is located below the recess of the conductive jumper element.

[0326] In certain embodiments, the recess includes exposed insulator.

[0327] In certain embodiments, the conductive jumper element includes a first terminal electrically connected to a second terminal with an exposed insulator between the first terminal and the second terminal, wherein the first terminal, the second terminal, and the exposed insulator form a planar surface on at least one side of the conductive jumper element.

[0328] In certain embodiments, the device includes a third electrical conductor on the conductor substrate that is electrically isolated from the first electrical conductor and the second electrical conductor, wherein the third electrical conductor is contacted by the exposed insulator.

[0329] In certain embodiments, a portion of at least one of the jumper conductors is covered with an insulator.

[0330] In certain embodiments, a central portion of at least one of the jumper conductors is covered with an insulator separating exposed ends of the jumper conductor.

[0331] In certain embodiments, the substrate is a display substrate and the conductive jumper element electrically connects the redundant light emitter to the display circuitry.

[0332] In certain embodiments, the redundant light emitter is connected to the display circuit in place of a defective primary light emitter.

[0333] In some embodiments, the distance between the first electrical conductor and the second electrical conductor is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns. In some embodiments, the device substrate has a thickness from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm.

[0334] In some embodiments, the conductive jumper element has a width of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, the conductive jumper element has a length of from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm. In some embodiments, the conductive jumper element has a height of from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0335] In some embodiments, the device substrate has a transparency greater than or equal to 50%, 80%, 90% or 95% for visible light. In some embodiments, the device substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor and sapphire.

[0336] In certain embodiments, the conductive jumper element is a crossover wire.

[0337] In certain embodiments, the device includes: a plurality of first electrical conductors located on the device substrate, wherein the plurality of first electrical conductors include the first electrical conductors; a plurality of second electrical conductors located on the device substrate, wherein the plurality of second electrical conductors include the second electrical conductors; a conductive jumper element that is different and separate from the device substrate and has a plurality of jumper conductors, wherein the plurality of jumper conductors include the one or more jumper conductors; and each of the plurality of jumper conductors is in electrical contact with a first electrical conductor among the plurality of first electrical conductors and a second electrical conductor among the plurality of second electrical conductors.

[0338] In another aspect, the present invention is directed to a method for providing a microassembled device, comprising: providing a device comprising: a device substrate; a first electrical conductor located on the device substrate; a second electrical conductor located on the device substrate; and microassembling a conductive jumper element having one or more jumper conductors on the device substrate, wherein the conductive jumper element is located on the device substrate, wherein a first jumper conductor of the one or more jumper conductors is in electrical contact with the first electrical conductor and the second electrical conductor.

[0339] In some embodiments, the conductive jumper element is a conductive passive device. In some embodiments, the conductive jumper element is an active device. In some embodiments, the active device is a CMOS device. In some embodiments, the active device includes at least one of a drive circuit and a non-volatile memory.

[0340] In certain embodiments, the conductive jumper element is housed within a structure suitable for micro-transfer printing.

[0341] In certain embodiments, the conductive jumper element includes one or more of a semiconductor, silicon, silicon-on-insulator, glass, metal, and a dielectric.

[0342] In certain embodiments, the jumper conductor includes a semiconductor, a metal, a precious metal, gold, silver, platinum, copper, stainless steel, nickel, chromium, solder, PbSn, or AgSn.

[0343] In certain embodiments, a portion of the conductive jumper element adjacent to the conductor substrate is recessed.

[0344] In certain embodiments, the device includes a third electrical conductor on the conductor substrate that is electrically isolated from the first electrical conductor and the second electrical conductor, wherein the third electrical conductor is located below the recess of the conductive jumper element.

[0345] In certain embodiments, the recess includes exposed insulator.

[0346] In certain embodiments, the conductive jumper element includes a first terminal electrically connected to a second terminal with an exposed insulator between the first terminal and the second terminal, wherein the first terminal, the second terminal, and the exposed insulator form a planar surface on at least one side of the conductive jumper element.

[0347] In certain embodiments, the method includes a third electrical conductor on the conductor substrate that is electrically isolated from the first electrical conductor and the second electrical conductor, wherein the third electrical conductor is contacted by the exposed insulator.

[0348] In certain embodiments, a portion of at least one of the jumper conductors is covered with an insulator.

[0349] In certain embodiments, a central portion of at least one of the jumper conductors is covered with an insulator separating exposed ends of the jumper conductor.

[0350] In certain embodiments, the substrate is a display substrate and the conductive jumper element electrically connects the redundant light emitter to the display circuitry.

[0351] In certain embodiments, the redundant light emitter is connected to the display circuit in place of a defective primary light emitter.

[0352] In certain embodiments, the distance between the first electrical conductor and the second electrical conductor is from 100 nm to 500 nm, from 500 nm to 1 micron, from 1 micron to 20 microns, from 20 microns to 50 microns, or from 50 microns to 100 microns.

[0353] In certain embodiments, the device substrate has a thickness from 5 microns to 10 microns, from 10 microns to 50 microns, from 50 microns to 100 microns, from 100 microns to 200 microns, from 200 microns to 500 microns, from 500 microns to 0.5 mm, from 0.5 mm to 1 mm, from 1 mm to 5 mm, from 5 mm to 10 mm, or from 10 mm to 20 mm.

[0354] In certain embodiments, the conductive jumper element has a width from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0355] In certain embodiments, the conductive jumper element has a length from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0356] In certain embodiments, the conductive jumper element has a height of from 2 μm to 5 μm, from 4 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0357] In certain embodiments, the device substrate has a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light.

[0358] In certain embodiments, the device substrate is a component selected from the group consisting of: polymer, plastic, resin, polyimide, PEN, PET, metal, metal foil, glass, semiconductor, and sapphire.

[0359] In certain embodiments, the conductive jumper element is a crossover wire.

[0360] In certain embodiments, the method includes: a plurality of first electrical conductors located on the device substrate, wherein the plurality of first electrical conductors include the first electrical conductor; a plurality of second electrical conductors located on the device substrate, wherein the plurality of second electrical conductors include the second electrical conductor; a conductive jumper element that is different and separate from the device substrate and has a plurality of jumper conductors, wherein the plurality of jumper conductors include the one or more jumper conductors; and each of the plurality of jumper conductors is in electrical contact with a first electrical conductor among the plurality of first electrical conductors and a second electrical conductor among the plurality of second electrical conductors.

[0361] In certain embodiments, microassembling the conductive jumper element includes: contacting the conductive jumper element with a transfer device having a contact surface, thereby temporarily bonding the conductive jumper element to the contact surface so that the conductive jumper element is temporarily placed on the contact surface; contacting the conductive jumper element placed on the contact surface of the transfer device with a receiving surface of the device substrate; and separating the contact surface of the transfer device from the conductive jumper element, wherein the conductive jumper element is transferred to the receiving surface, thereby assembling the portion of the conductive jumper element on the receiving surface of the device substrate.

[0362] In certain embodiments, the transfer device comprises an elastomeric stamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0363] The foregoing and other objects, aspects, features and advantages of the present invention will become more apparent and better understood through the following description made with reference to the accompanying drawings, in which:

[0364] Figure 1 is a diagrammatic illustration of a typical pixel used in an LCD display;

[0365] Figure 2 is a diagrammatic illustration of an example pixel constructed according to the disclosed technology;

[0366] Figure 3 is a micrograph of smaller micro-LEDs assembled on a display substrate using microassembly;

[0367] Figure 4 is a diagrammatic illustration of an example micro LED display including redundant RGB inorganic micro LEDs according to an illustrative embodiment of the invention;

[0368] Figure 5 is a diagrammatic illustration of an example pixel according to the disclosed technology;

[0369] Figure 6 is a diagrammatic illustration of an example pixel of a display with missing micro-LEDs according to an illustrative embodiment of the invention;

[0370] Figure 7 is a diagrammatic illustration of a micro-assembled display including redundant RGB inorganic micro-LEDs, driver ICs, and micro-sensors according to an illustrative embodiment of the invention;

[0371] Figures 8A to 8D is a diagrammatic illustration of redundant micro-LEDs in a micro-LED panel for micro-assembled display and lighting elements according to an illustrative embodiment of the invention;

[0372] Figures 9A to 9C is a schematic diagram illustrating a micro-transfer printed array of micro-LEDs on glass according to an illustrative embodiment of the present invention;

[0373] Fig.10 is a diagrammatic illustration of an exemplary structure for repairing a micro LED array device using micro-assembly jumpers according to an illustrative embodiment of the present invention;

[0374] Fig.11A and 11B illustrates a micro-assembly crossover line for layer reduction in a micro LED array device according to an illustrative embodiment of the invention;

[0375] Fig. 12A and 12B is a diagrammatic illustration of an example circuit using resistors and diodes to facilitate repair by providing electrical signatures of redundant micro-assembled micro LED pixels or sub-pixels in a lighting element or display in accordance with an illustrative embodiment of the invention;

[0376] Fig.13 An electrical connector suitable for micro-assembly is illustrated according to an illustrative embodiment of the invention;

[0377] Fig.14 is a diagrammatic illustration of a micro-assembled display including complementary RGB inorganic micro-LEDs according to an illustrative embodiment of the present invention;

[0378] Fig.15A and 15B is a diagrammatic illustration of a micro-assembled micro LED display and lighting element architecture according to an illustrative embodiment of the present invention;

[0379] Fig.16 illustrates a micro-assembled micro LED display and lighting element architecture according to an illustrative embodiment of the invention;

[0380] Fig.17 is a diagrammatic illustration of an example display formed of two independent displays occupying the same viewable area in accordance with an illustrative embodiment of the present invention;

[0381] Fig.18 is a diagrammatic illustration of a stacked micro-LED display according to an illustrative embodiment of the present invention;

[0382] Fig.19 is a diagrammatic illustration of a micro-assembled stacked display formed from three display panels in accordance with an illustrative embodiment of the present invention;

[0383] Fig. 20 is a diagrammatic illustration of a stacked display formed from two individual displays having different resolutions in accordance with an illustrative embodiment of the invention;

[0384] Fig.21 is a diagrammatic illustration of an example pixel of a multi-mode display according to an illustrative embodiment of the invention;

[0385] Fig. 22 is a diagrammatic illustration of an example pixel of a multi-mode display according to an illustrative embodiment of the invention;

[0386] Fig.23 is a diagrammatic illustration of a pixel having an integrated circuit and a microsensor connected to redundant micro-LEDs according to an illustrative embodiment of the invention;

[0387] Fig.24 is an example graphical illustration of the color gamut of human vision and HDTV according to an illustrative embodiment of the present invention;

[0388] Fig.25 is a graphical illustration of an example pixel with improved color gamut according to an illustrative embodiment of the invention;

[0389] Fig.26 is a diagrammatic illustration of an exemplary pixel for use in a micro-assembled inorganic micro-LED array for producing a visually perfect device in accordance with an illustrative embodiment of the invention;

[0390] Fig.27A and 27B is a diagrammatic illustration of two micro-assembled inorganic micro-LED array strategies for producing a visually perfect device according to an illustrative embodiment of the present invention;

[0391] Fig.28 is a diagrammatic illustration of an example pixel prior to connection according to an illustrative embodiment of the present invention;

[0392] Fig.29 is a diagrammatic illustration of implementing color conversion in a micro-assembled micro-LED display and lighting element using color conversion materials according to an illustrative embodiment of the present invention;

[0393] Fig. 30A and 30Bare respectively a micrograph and a diagrammatic illustration of an apparatus for using a self-aligned dielectric for micro-assembly of micro-LED display and lighting elements according to an illustrative embodiment of the present invention;

[0394] Fig.31 is a diagrammatic illustration of an exemplary 4×4 array of functional elements controlled by a single microassembled integrated circuit in accordance with an illustrative embodiment of the present invention;

[0395] Fig.32 illustrates an exemplary device of several 4×4 arrays of functional elements each controlled by a single micro-assembled integrated circuit in accordance with an illustrative embodiment of the invention;

[0396] Fig.33 is a diagrammatic illustration of an exemplary array of using a control element to control different types of functional elements according to an illustrative embodiment of the invention;

[0397] Fig.34 is a diagrammatic illustration of a display formed using microassembly having clusters of integrated circuit pixels that can each function as an independent display in accordance with an illustrative embodiment of the invention;

[0398] Fig.35 is a graphical illustration of an example in which a user has chosen to turn on only a portion of the entire device in accordance with an illustrative embodiment of the present invention;

[0399] Fig.36 is a graphical illustration of an example in which a user has chosen to turn on only a portion of an overall device in a non-standard shape, according to an illustrative embodiment of the invention;

[0400] Fig.37 is a diagrammatic illustration of an example array with wireless data and / or power input according to an illustrative embodiment of the invention;

[0401] Fig.38 is a diagrammatic illustration of a control element designed with built-in redundancy according to an illustrative embodiment of the present invention;

[0402] Fig.39 is a diagrammatic illustration of an array having control devices including built-in memory according to an illustrative embodiment of the present invention;

[0403] Fig.40 is a diagrammatic illustration of a micro-assembled micro LED display having a micro-assembled temperature sensing element according to an illustrative embodiment of the invention;

[0404] Fig.41 is an image of a passive matrix inorganic light emitting diode display according to an illustrative embodiment of the present invention;

[0405] Fig.42is an optical micrograph of a pixel within a display according to an illustrative embodiment of the present invention;

[0406] Fig.43 is an optical micrograph of a single pixel within a display according to an illustrative embodiment of the present invention;

[0407] Fig.44 is an image of a complete display substrate having a passive matrix display thereon according to an illustrative embodiment of the present invention;

[0408] Fig.45 is an optical micrograph of a pixel array of a display according to an illustrative embodiment of the present invention;

[0409] Fig.46 is a flow chart of a method for manufacturing a passive matrix inorganic light emitting diode display according to an illustrative embodiment of the present invention;

[0410] Fig.47A is an image of a passive matrix inorganic light emitting diode display according to an illustrative embodiment of the present invention;

[0411] Fig.47B According to an illustrative embodiment of the present invention Fig.47A Close-up image of a passive matrix inorganic light-emitting diode display;

[0412] Fig.48A is an image of a passive matrix inorganic light emitting diode display according to an illustrative embodiment of the present invention;

[0413] Fig.48B According to an illustrative embodiment of the present invention Fig.48A Close-up image of a passive matrix inorganic light-emitting diode display;

[0414] Figures 49A to 49G is an image showing that the display is partially transparent according to an illustrative embodiment of the present invention;

[0415] Fig.50 is an optical micrograph of an exemplary printed LED wired in a passive matrix configuration;

[0416] Fig.51 are schematic and optical micrographs of an exemplary printed LED wired in a passive matrix configuration;

[0417] Fig.52 is an optical micrograph of a single LED wired in a passive matrix configuration;

[0418] Fig.53A and 53B are a plan view and a cross section, respectively, of an exemplary architecture of a micro-LED suitable for contacting two terminals from one side of the LED; and

[0419] Figures 54A to 54E is a schematic cross-section of an example architecture of a micro-LED.

[0420] The features and advantages of the present invention will become more apparent from the detailed description set forth below in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. DETAILED DESCRIPTION

[0421] As used herein, the expressions "semiconductor element" and "semiconductor structure" are used synonymously and broadly refer to semiconductor materials, structures, devices, or components of devices. Semiconductor elements include high-quality single crystal and polycrystalline semiconductors, semiconductor materials made through high temperature processing, doped semiconductor materials, organic and inorganic semiconductors, and composite semiconductor materials and structures with one or more additional semiconductor components and / or non-semiconductor components (such as dielectric layers or materials and / or conductive layers or materials). Semiconductor elements include semiconductor devices and device components, including but not limited to transistors, photovoltaic devices including solar cells, diodes, light emitting diodes, lasers, pn junctions, photodiodes, integrated circuits, and sensors. In addition, semiconductor elements may refer to parts or portions that form a functional semiconductor device or product.

[0422] "Semiconductor" refers to any material that is an insulator at very low temperatures but has appreciable electrical conductivity at temperatures of about 300 kelvins. The electrical properties of a semiconductor can be modified by the addition of impurities or dopants and controlled by the use of electric fields. In this description, usage of the term semiconductor is intended to be consistent with usage of this term in the field of microelectronics and electronic devices. Semiconductors useful in the present invention may include elemental semiconductors such as silicon, germanium, and diamond, and compound semiconductors of, for example, Group IV compound semiconductors such as SiC and SiGe; Group III-V semiconductors such as AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP; Group III-V ternary semiconductor alloys such as Al; × Ga 1-xAs; II-VI semiconductors such as CsSe, CdS, CdTe, ZnO, ZnSe, ZnS and ZnTe; I-VII semiconductors CuCl; IV-VI semiconductors such as PbS, PbTe and SnS; layered semiconductors such as PbI2, MoS2 and GaSe; oxide semiconductors such as CuO and Cu2O. The term semiconductor includes intrinsic semiconductors and non-intrinsic semiconductors doped with one or more selected materials, including semiconductors with p-type doped materials and n-type doped materials to provide beneficial electronic properties suitable for a given application or device. The term semiconductor includes composite materials including mixtures of semiconductors and / or dopants. Specific semiconductor materials useful in some applications of the present invention include, but are not limited to: Si, Ge, SiC, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InP, InAs, GaSb, InP, InAs, InSb, ZnO, ZnSe, ZnTe, CdS, CdSe, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, PbS, PbSe, PbTe, AlGaAs, AlInAs, AlInP, GaAsP, GaInAs, GaInP, AlGaAsSb, AlGaInP, and GaInAsP. Porous silicon semiconductor materials are useful for applications of the present invention in the fields of sensors and light emitting materials, such as light emitting diodes (LEDs) and solid state lasers. Impurities of semiconductor materials are atoms, elements, ions, and / or molecules other than the semiconductor material itself, or any dopant provided in the semiconductor material. Impurities are undesirable materials present in semiconductor materials that may negatively affect the electronic properties of the semiconductor material and include, but are not limited to, oxygen, carbon, and metals, including heavy metals. Heavy metal impurities include, but are not limited to, the group of elements between copper and lead on the periodic table, calcium, sodium, and all ions, compounds, and / or complexes thereof.

[0423] "Substrate" refers to a structure or material on or in which a process (e.g., patterning, assembly, or integration of semiconductor elements) is (or has been) performed. Substrates include, but are not limited to: (i) structures on which semiconductor elements are fabricated, deposited, transferred, or supported (also referred to as homogeneous substrates); (ii) device substrates, for example, electronic device substrates; (iii) donor substrates having elements such as semiconductor elements for subsequent transfer, assembly, or integration; and (iv) target substrates for receiving printable structures such as semiconductor elements. The donor substrate may be, but is not necessarily, a homogeneous substrate.

[0424] As used herein, "display substrate" refers to a target substrate (e.g., a non-homogeneous substrate) for receiving printable structures such as semiconductor elements. Examples of display substrate materials include polymers, plastics, resins, polyimides, polyethylene naphthalate, polyethylene terephthalate, metals, metal foils, glass, flexible glass, semiconductors, and sapphire.

[0425] As used herein, the terms "micro" and "microdevice" refer to the descriptive size of a particular device or structure according to embodiments of the present invention. As used herein, the terms "micro" and "microdevice" are intended to refer to structures or devices on a scale of 0.5 μm to 250 μm. However, it will be appreciated that embodiments of the present invention are not necessarily limited thereto, and certain aspects of the embodiments may be applicable to larger or smaller size scales.

[0426] As used herein, "micro-LED" refers to an inorganic light emitting diode that is sized from 0.5 μm to 250 μm. For example, a micro-LED may have at least one (or two or all three) of a width, length, and height from 0.5 μm to 2 μm, from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, from 20 μm to 50 μm, from 50 μm to 100 μm, or from 100 μm to 250 μm. The micro-LED emits light when enabled. The color of the light emitted by the LED varies depending on the structure of the micro-LED. For example, when enabled, a red micro-LED emits red light, a green micro-LED emits green light, a blue micro-LED emits blue light, a yellow micro-LED emits yellow light, and a cyan micro-LED emits cyan light.

[0427] "Printable" refers to a material, structure, device component, or integrated functional device that can be transferred, assembled, patterned, organized, or integrated onto or into a substrate without exposing the substrate to elevated temperatures (e.g., at temperatures less than or equal to about 400, 200, or 150 degrees Celsius). In one embodiment of the present invention, the printable material, element, device component, or device can be transferred, assembled, patterned, organized, and / or integrated onto or into a substrate via stock solution printing, microtransfer printing, or dry transfer contact printing.

[0428] The "printable semiconductor elements" of the present invention include semiconductor structures that can be assembled or integrated onto the surface of a substrate, for example, by using dry transfer contact printing, microtransfer printing, or solution printing methods. In one embodiment, the printable semiconductor element of the present invention is a single single crystal, polycrystalline, or microcrystalline inorganic semiconductor structure. In the context of this description, a single structure is a monolithic element having mechanically connected features. The semiconductor elements of the present invention may be undoped or doped, may have a selected spatial distribution of dopants, and may be doped with a variety of different dopant materials, including p-type and n-type dopants. The present invention includes microstructured printable semiconductor elements having at least one cross-sectional dimension greater than or equal to about 1 micron and nanostructured printable semiconductor elements having at least one cross-sectional dimension less than or equal to about 1 micron. Printable semiconductor elements useful in many applications include elements obtained from "top-down" processing of high-purity bulk materials (e.g., high-purity crystalline semiconductor wafers produced using conventional high-temperature processing techniques). In one embodiment, the printable semiconductor element of the present invention comprises a composite structure having a semiconductor operatively connected to at least one additional device component or structure (e.g., a conductive layer, a dielectric layer, an electrode, an additional semiconductor structure, or any combination of these). In one embodiment, the printable semiconductor element of the present invention comprises a stretchable semiconductor element or a heterogeneous semiconductor element.

[0429] The term "flexible" refers to the ability of a material, structure, device, or device component to reversibly deform into a curved shape, for example, without undergoing a transformation that causes significant strain (e.g., strain characterized by a point of failure of the material, structure, device, or device component).

[0430] "Plastic" refers to any synthetic or naturally occurring material or combination of materials that can be molded or shaped (usually when heated) and hardened into a desired shape. Exemplary plastics useful in the devices and methods of the present invention include, but are not limited to, polymers, resins, and cellulose derivatives. In this description, the term plastic is intended to include composite plastic materials that include one or more plastics and one or more additives, such as structural reinforcements, fillers, fibers, plasticizers, stabilizers, or additives that can provide desired chemical or physical properties. "Dielectric" and "dielectric material" are used synonymously in this description and refer to substances that are highly resistant to the flow of electric current and can be polarized by an applied electric field. Useful dielectric materials include, but are not limited to, SiO2, Ta2O5, TiO2, ZrO2, Y2O3, SiN4, STO, BST, PLZT, PMN, and PZT.

[0431] "Polymer" refers to a molecule comprising a plurality of repeating chemical groups (commonly referred to as monomers). Polymers are generally characterized by high molecular weight. Polymers useful in the present invention may be organic polymers or inorganic polymers and may be in an amorphous, semi-amorphous, crystalline or partially crystalline state. Polymers may include monomers having the same chemical composition or may include multiple monomers having different chemical compositions, such as copolymers. Cross-linked polymers having linked monomer chains are particularly useful for some applications of the present invention. Polymers useful in the methods, devices and device components of the present invention include, but are not limited to, plastics, elastomers, thermoplastic elastomers, elastomeric plastics, thermostats, thermoplastics and acrylates. Exemplary polymers include, but are not limited to, acetal polymers, biodegradable polymers, cellulosic polymers, fluoropolymers, nylon, polyacrylonitrile polymers, polyamide-imide polymers, imides, polyarylates, polybenzimidazoles, polybutylenes, polycarbonates, polyesters, polyetherimides, polyethylene, polyethylene copolymers and modified polyethylenes, polyketones, polymethyl methacrylates, polymethylpentenes, polyphenylene oxides and polyphenylene sulfides, polyphthalamides, polypropylene, polyurethanes, styrene resins, sulfone-based resins, vinyl resins, or any combination of these.

[0432] As used herein, "micro-transfer printing" refers to systems, methods and techniques for deterministically assembling micro- and nano-type materials, devices and semiconductor elements into spatially organized, functionally arranged devices with two-dimensional and three-dimensional layouts. It is usually difficult to pick up and place ultra-thin or small devices, however, micro-transfer printing allows the selection and application of these ultra-thin, fragile or small devices (such as micro-LEDs) without causing damage to the device itself. Microstructure stamps (e.g., elastic stamps, electrostatic stamps or hybrid elastic / electrostatic stamps) can be used to pick up micro-devices, transport the micro-devices to the destination substrate, and print the micro-devices onto the destination substrate. In some embodiments, surface adhesion is used to control the selection of these devices and print them onto the destination substrate. This process can be performed in parallel on a large scale. The stamp can be designed to transfer a single device or hundreds to thousands of discrete structures in a single pick-up and printing operation. For discussion of micro-transfer printing, see U.S. Pat. Nos. 7,622,367 and 8,506,867, each of which is hereby incorporated by reference in its entirety.

[0433] Microtransfer printing also enables the parallel assembly of high-performance semiconductor devices (e.g., micro-LED displays) onto nearly any substrate material, including glass, plastic, metal, other semiconductor materials, or other non-semiconductor materials. The substrate can be flexible, thereby permitting the creation of flexible electronic devices. Flexible substrates can be integrated into a large number of configurations, including configurations that are not possible with brittle silicon-based electronic devices. Additionally, for example, plastic substrates are mechanically strong and can be used to provide electronic devices that are less susceptible to damage or degradation of electronic performance caused by mechanical stress. Therefore, these materials can be used to make electronic devices by continuous, high-speed printing techniques (e.g., roll-to-roll manufacturing) that can produce electronic devices over large substrate areas at low cost.

[0434] Furthermore, these microtransfer printing techniques can be used to print semiconductor devices at temperatures compatible with assembly on plastic polymer substrates. In addition, semiconductor materials can be printed onto large area substrates, thereby enabling continuous, high-speed printing of complex integrated circuits over large substrate areas. Furthermore, flexible electronic devices with good electronic performance in flexible or deformable device orientations can be provided to enable a wide range of flexible electronic devices.

[0435] The disclosed technology generally relates to the formation of transferable micro inorganic light emitting diode (e.g., micro LED) devices. Micro-assembled micro LED displays and lighting elements use micro LED arrays that are too small, too numerous, or too fragile to be assembled by conventional means (e.g., vacuum grippers or pick-and-place tools). The disclosed technology uses micro transfer printing technology to achieve micro-assembled micro LED displays and lighting elements. Micro LEDs can be prepared on a homogenous substrate and printed to a destination substrate (e.g., plastic, metal, glass, or other material) such as a display substrate. This enables a small active area display because semiconductor material is only used for the micro LEDs or other active elements (e.g., drivers or transistors) and not across the entire display panel or a large portion thereof (as typically found in thin film displays) (e.g., in certain embodiments, the present invention provides a display substrate having an active area less than or equal to 40%, 30%, 20%, 10%, 5%, 3%, 1%, 0.5%, or 0.1% of the display). In some embodiments, the combined light emitting area of ​​the light emitters is less than or equal to one eighth, one tenth, one twentieth, one fiftieth, one hundredth, one five hundredth, one thousandth, one two thousandth, or one ten thousandth of the continuous display substrate area.

[0436] Micro-assembled micro-LED displays and lighting elements can provide substantially monochromatic, substantially white, or substantially tunable colors. They can include micro-LEDs that emit substantially similar colors, for example, all blue or all red micro-LEDs, or they can include micro-LEDs of different colors, for example, red, green, blue, yellow, or cyan micro-LEDs for reproducing different colors on a display or lighting element. The color of the micro-LEDs can be produced by direct emission from the micro-LEDs, by a color conversion structure, or some combination thereof.

[0437] In some embodiments, the micro-LEDs used in the disclosed displays benefit from passivation of the active-junction perimeter. For example, before printing the micro-LEDs onto the display substrate, the junction perimeter of each micro-LED diode can be exposed (e.g., by etching) and a high bandgap semiconductor (e.g., InGaAlP, InGaN, GaN, AlGaN) can be grown on the exposed junction perimeter, thereby reducing non-radiative recombination in the micro-LEDs.

[0438] Furthermore, in certain embodiments, micro-LEDs carry more current laterally than conventional LEDs by a distance. Therefore, the micro-LED epitaxial structure can be thinner than that used for conventional LEDs. Micro-LED epitaxial structures for displays may include thinner current spreading layers or thinner buffer layers. In certain embodiments, conventional buffer layers may be omitted due to the epitaxial structure of the micro-LEDs. Buffer layers are typically required as the thickness of the device increases to prevent cracking of the device substrate. The disclosed technology provides such devices (e.g., in some embodiments, devices less than one millimeter thick). Thin devices such as these devices do not require buffer layers to prevent cracking of the substrate / device. In some embodiments, thinner, strain-balanced alternating epitaxial layers can be used to replace conventional buffer layers. By using alternating layers of crystalline materials with different lattice structures, an entire structure with reduced strain is provided that can also perform the full function of an epitaxial layer (for example, for current conduction or light emission).

[0439] Figure 11 is a prior art illustration of a typical pixel 100 used in, for example, an LCD display. Pixel 100 includes three sub-pixels 104a, 104b, and 140c (collectively 104). In some cases, these sub-pixels are red sub-pixel 104a, green sub-pixel 104b, and blue sub-pixel 104c. Color filters are typically used to form the color of each sub-pixel 104 when a backlight is used to illuminate the filter. The intensity of each sub-pixel 104 can be controlled by a change in the voltage applied to each sub-pixel 104 so that each sub-pixel 104 produces a wide range of shades (e.g., 256 shades of red, 256 shades of green, and 256 shades of blue). In a liquid crystal display, a voltage is applied to the liquid crystals in the liquid crystal layer. The liquid crystals twist based on the applied voltage, thereby varying the amount of light from the backlight that passes through the liquid crystals and, therefore, the color filters for each sub-pixel 104.

[0440] Figure 2 is a diagrammatic illustration of an example pixel 200 constructed according to the disclosed techniques. In this example, the pixel 200 has a Figure 1 The size of the pixel shown is 100, however, Figure 2 The pixel 200 shown in FIG. 1 is constructed using micro-LEDs 202a to 202f (collectively referred to as micro-LEDs 202). Micro-LEDs 202 may be micro-transfer printed onto a substrate (e.g., a transparent (including translucent, nearly transparent, and mostly transparent) or flexible substrate). In some embodiments, the substrate is plastic, glass, metal, or sapphire.

[0441] Micro-assembly sparse integration of high performance light emitters (e.g., micro-LEDs 202) and driver circuits 204 (e.g., micro-integrated circuits) enables displays that are flexible, bright, draw less power, or occupy only a small portion of the display substrate. In some embodiments, the additional free space facilitates positioning of higher function devices (e.g., micro-sensors 206) on the display plane, such as devices that enable gesture transmission, power harvesting, light emitter redundancy, image capture, and wireless operation. For example, in some embodiments, the display includes a micro-integrated driver circuit 204 in each pixel. Additionally, in some embodiments, the small operating area occupied by the micro-LEDs enables the construction of transparent displays, multi-mode displays, redundant micro-LEDs and other devices, and ultra-bright displays.

[0442] Figure 3Illustrated is an LED assembled on a display substrate using microassembly (e.g., microtransfer printing). Small LEDs are placed on a display substrate and electrically connected in series, in parallel, or in an active matrix, a passive matrix, or a combination thereof. Microassembled LED displays and lighting elements exhibit many desirable properties, including excellent color quality in some embodiments. They are highly efficient and have low power consumption.

[0443] As shown in this example, a micro-assembled LED display can be produced to be transparent (e.g., having a transparency greater than or equal to 50%, 80%, 90%, or 95% for visible light). The transparency can be based at least in part on the minimal low area coverage or transparency of the micro-LEDs, connecting features, and other components. The transparency is apparent in the "off" state of the device or when viewed from a particular orientation (e.g., from the side of the device opposite the viewing direction). The transparency can enable a virtually invisible display or light source. Figures 49A to 49G An example partially transparent display constructed using a glass substrate is illustrated. In some embodiments, partial or actual transparency is achieved without the need for microassembly techniques, provided the pixel density is low enough and the intended proximity of the viewer is far enough.

[0444] Figure 4 4 is an illustration of an example of a micro LED display 400 including redundant RGB inorganic micro LEDs 402a-402x, driver circuits 406 (e.g., microtransfer printed integrated circuits), and micro sensors 404a and 404b (collectively, micro sensors 404). In some embodiments, display 400 is formed on a display substrate that may be a polymer, plastic, resin, polyimide, polyethylene naphthalate, polyethylene terephthalate, metal, metal foil, glass, semiconductor, or sapphire. Display 400 includes microtransfer printed redundant RGB micro LEDs 402a-402x that exhibit low power consumption while still projecting clear light. Each primary micro-LED (e.g., 402a, 402c, 402e, 402g, 402i, 402k, 402m, 402o, 402q, 402s, 402u, 402w) includes a corresponding redundant, backup micro-LED (e.g., 402b, 402d, 402f, 402h, 402j, 402l, 402n, 402p, 402r, 402t, 402v, 402x, respectively). Sparsely integrated micro-LEDs 402 allow other functional devices to be placed within each pixel, such as micro-sensors 404a and 404b, power harvesting devices, gesture sensors, or image capture devices.

[0445] A micro-integrated driver circuit 406 (e.g., a CMOS circuit) may be micro-transfer printed to drive the micro-LEDs 402. The micro-integrated driver circuit 406 may include embedded memory (e.g., non-volatile memory). The memory may be used to display static images without constantly needing to refresh the display (e.g., thereby saving power). The memory may also store, for example, a lookup table for adjusting the output of the micro-LEDs in the display. In some embodiments, a micro-integrated driver circuit 406 is positioned on each pixel to drive each micro-LED in the respective pixel.

[0446] In addition to emitting light from the front of display 400, micro-LEDs 402a to 402x can also emit light from the back of display 400. Display 400 can include an adhesive layer on one side, resulting in a sticker-like display. The wiring used in the display (e.g., wiring used to electrically couple micro-LEDs 402 and micro-sensors 404 to integrated driver circuit 406) can be fine wires (e.g., having a critical dimension of less than 1 μm and an overlay accuracy of less than 0.25 μm) or transparent wires.

[0447] Figure 7 is an illustration of a micro-assembled display 700 that includes primary and redundant RGB inorganic micro-LEDs 702a to 702x (collectively, micro-LEDs 702) arranged in primary and redundant inorganic micro-LED pairs, a driver IC 706, and micro-sensors 704a and 704b (collectively, micro-sensors 704) on a substrate. The substrate may be transparent or flexible. A lookup table may be used to electronically generate a visually perfect display by providing additional light from one of the micro-LEDs in a redundant pair (e.g., micro-LEDs 702a and 702b) in the event that the counterpart of the micro-LED is inoperative. For example, if micro-LED 702a is inoperative, driver 706 may cause micro-LED 702b to activate to compensate for micro-LED 702a. In another example, if all micro-LEDs are driven to provide a high-resolution display, micro-LED 702b may be driven to provide additional light (e.g., brighter) to compensate for micro-LED 702a in the event that micro-LED 702a is inoperative.

[0448] Figure 5is an illustration of an example pixel 500 according to the disclosed technology. As explained above, small micro-LEDs 502 allow for redundancy (e.g., LEDs having at least one of a width, length, and height from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, from 20 μm to 50 μm, from 50 μm to 100 μm, or from 100 μm to 250 μm). Redundancy can produce a visually perfect display and account for failed micro-LEDs (e.g., a display produced with an electrically shorted or open micro-LED). In some embodiments, if one micro-LED is defective or missing, this will be corrected by external drive electronics. For example, each micro-LED (e.g., 502a, 502c, and 502e) can have a corresponding spare or redundant micro-LED (e.g., 502b, 502d, 502f, respectively), thereby providing two staggered displays - a primary display and a secondary display that can be activated based on individual micro-LEDs. In some embodiments, both primary and secondary micro-LEDs are routed to a display or integrated circuit. In some embodiments, redundant micro-LEDs are routed on an individual basis after testing the display. In this example, red primary micro-LED 502a has a corresponding redundant red micro-LED 502b, blue LED 502c has a corresponding redundant blue micro-LED 502d, and green LED 502e has a corresponding redundant green micro-LED 502f.

[0449] Each micro-LED can have its own pixel driver (e.g., transistor circuit). This can be used to form a high-resolution display. The micro-LEDs can be selected to operate in a number of different modes (e.g., normal operating mode or high-resolution mode). This provides a tunable resolution that can be set automatically (e.g., based on the material being viewed on the display) or by the user (e.g., more light emitters can be activated as needed to provide a higher resolution display).

[0450] In some embodiments, the display has a tunable brightness dynamic range. If more emitters are turned on, the display will be brighter. This is useful for various applications, including improving daylight readability or in bright ambient environments. The display can also be used to form a color tunable flash by activating a mix of micro-LEDs (e.g., to provide a warm glow). Alternatively, the micro-LEDs can be provided in a dense pattern to increase the intensity of the flash.

[0451] Redundant pairs of micro-LEDs may be physically connected in series or in parallel before or after a repair operation. Physical repair may include laser cutting of unwanted electrical traces, direct writing of electrical traces by chemical vapor deposition or laser-assisted chemical vapor deposition, or inkjet printing. Redundant pairs of micro-LEDs may be electrically independent and independently operated. Displays may also utilize redundant drive circuits and display control elements for improved information display fidelity or to facilitate the creation of visually perfect displays.

[0452] Figure 6 is an illustration of an example multi-color pixel 600 of a display with a missing micro-LED 604. In this example, pixel 600 is designed to include a set of primary RGB micro-LEDs (red micro-LED 602a, green micro-LED 604, and blue micro-LED 602d) and a set of spare RGB micro-LEDs (red micro-LED 602b, green micro-LED 602c, and blue micro-LED 602e). However, in this case, primary green micro-LED 604 is missing or inoperable while primary blue micro-LED 602d and red micro-LED 602a are present and operational. Primary green micro-LED 604 may have been accidentally omitted (e.g., due to a printing error), it may have been removed after printing because it is a defective micro-LED, or it may be present but inoperative (e.g., open circuit). Spare green micro-LED 602c may supplement omitted primary green micro-LED 604. The spare red and blue micro-LEDs can be turned off when the main red micro-LED 602a and the main blue micro-LED 602d are in operation. In some embodiments, the electronic circuit senses the missing or defective micro-LED and activates the corresponding spare micro-LED. The driver circuit of the display can sense the defective micro-LED. In some embodiments, the defective micro-LED is sensed by a detection circuit separate from the display. The defective micro-LED can be removed or disconnected. In some embodiments, a replacement micro-LED is connected to replace the defective micro-LED. In some embodiments, the replacement micro-LED is connected and the defective micro-LED must be directly removed or disconnected as needed. In some embodiments, both the main micro-LED and the redundant micro-LED are connected to the display circuit and the driver circuit only drives the appropriate redundant spare micro-LED if the main micro-LED is defective.

[0453] Figures 8A to 8D Illustrate redundancy of micro-LEDs in micro-LED panels for micro-assembled display and lighting elements. Figures 8A to 8C yes Fig.8DRedundant micro-LEDs in micro-assembled micro-LED panels provide defect tolerance and facilitate the formation of visually perfect display and lighting elements. During the first connection step, as shown Fig. 8A , a small portion of micro-LEDs (e.g., micro-LED 802) are connected to form a circuit, while the remaining micro-LEDs (e.g., micro-LED 804) remain disconnected from the circuit and form redundant micro-LEDs (e.g., backup, spare, or replacement micro-LEDs that can be used to compensate for or replace a defective primary micro-LED). In some embodiments, when a connection is made to micro-LED 802, conductive contact features 806a and 806b are formed to redundant device 804 even though redundant device 804 is not connected to a larger circuit that includes micro-LED 802. The test procedure can be used to identify defective micro-LEDs or groups of micro-LEDs that are inadvertently disconnected from the circuit (e.g., "open") or inadvertently shorted. Figure 8B As shown in FIG, a redundant micro LED (e.g., micro LED 810) in close proximity to a defective non-redundant micro LED (e.g., micro LED 808) is connected to a circuit by directly and physically writing electrical traces. In some embodiments, the electrically shorted non-redundant micro LED (e.g., micro LED 812) is removed from the circuit using, for example, ablation. Figure 8C The circuit shown in is disconnected in a similar manner. In some embodiments, a defective non-redundant LED (eg, 812) is not disconnected after the corresponding redundant LED is connected to the display circuit.

[0454] Figures 9A to 9C is an image illustrating a micro-transfer printed array of micro-LEDs on a display substrate (e.g., glass). Each pixel 902 includes a main micro-LED 906 and a spare micro-LED 904 that can be connected after testing the display. When an open pixel is identified (for example, due to a missing or defective micro-LED), the micro-LED can be identified as follows: Fig. 9B (e.g., pixel 908 has a faulty primary micro-LED and a connected redundant micro-LED and pixel 910 has a missing primary micro-LED and a connected redundant micro-LED) and the connected spare micro-LED shown in 9C. In this example, inkjet printed colloidal silver particles are used as the connected spare micro-LED (e.g., Fig. 9BIn some embodiments, the unused redundant micro-LEDs are removed from the display. In some embodiments, the defective primary micro-LED is removed or disconnected (e.g., before or after connecting the corresponding redundant micro-LED). In some embodiments, if the defect causes the micro-LED to short, then the defective primary micro-LED is disconnected or removed (e.g., if the defect causes the defective primary micro-LED to open, then that micro-LED may not need to be removed). Fig. 9C In the example shown in FIG. 1 , the display includes 48 pixels, each pixel including a primary micro-LED and a redundant micro-LED, such as Fig. 9A Pixels 912a to 912f each include a defective main micro-LED and therefore redundant micro-LEDs have been electrically connected to the display circuitry to compensate / replace each of these defective main micro-LEDs.

[0455] Fig.10 1 is an illustration of an exemplary method for repairing a micro LED array device using micro assembly jumper wires to electrically connect a redundant micro LED 1004b because a primary micro LED 1006b is defective. Conductive jumper elements 1002 may be placed by micro assembly (e.g., micro transfer printing) for repairing a micro LED array device by establishing an electrical connection to a spare, redundant micro LED 1004b. In some embodiments, conductive structures are prepared for micro assembly and assembly, thereby electrically connecting the redundant micro LED 1004 to a display circuit. Connections between traces on the micro LED array device are established, thereby connecting the redundant micro LED 1004b to the rest of the connected array. Electrical connections may be established by solder reflow or contacts between clean metal surfaces using, for example, jumper wires 1002 (e.g., gold-gold interfaces).

[0456] As shown in this example, jumper 1002 is used to connect redundant micro-LED 1004b to effectively replace the defective main micro-LED 1006b. Redundant micro-LED 1004a is not connected in this example because the main micro-LED 1006a is functioning properly. In some embodiments, if the main micro-LED 1006a fails, the redundant micro-LED 1004a is connected at a later time. In some embodiments, the unused redundant micro-LED (e.g., micro-LED 1004a) is removed from the display. In some embodiments, the defective main micro-LED (e.g., micro-LED 1006b) is removed (e.g., before or after connecting the corresponding redundant micro-LED). In some embodiments, if the defect causes the micro-LED to short-circuit, the defective main micro-LED (e.g., 1006b or the main micro-LED discussed in other embodiments) is removed (e.g., if the defect causes the defective main micro-LED to open-circuit, then that micro-LED may not need to be removed).

[0457] Inoperative micro-LEDs can be sensed in several ways. For example, a camera can be used to detect light emitted from one or more micro-LEDs. The camera may be specific to a particular color spectrum. In some embodiments, the camera is a light sensor integrated into a display panel (e.g., a micro-sensor micro-assembled in or on the same panel or surface as the micro-LEDs). In some embodiments, the micro-light sensor is connected to a micro-integrated circuit (e.g., a micro-integrated circuit that forms a display driver for a pixel or display). In some embodiments, the light sensor signal is interpreted by the micro-integrated circuit. The micro-integrated circuit can drive secondary micro-LEDs in situations where the primary micro-LED is inoperative. In some embodiments, the micro-integrated circuit will not drive defective / inoperative micro-LEDs. The micro-integrated circuit can also change the extent to which it drives the primary micro-LED in certain situations to ensure that the appropriate color is output by the micro-LED (e.g., the correct shade of red). In some embodiments, the display can perform this analysis and correction after it has been manufactured and used by a consumer. This can increase the lifespan and quality of the display.

[0458] Fig.11A and 11BIllustrated are micro-assembly crossover lines 1102, 1104, and 1106 for layer reduction in a micro LED array device. It is generally advantageous to reduce the number of processing steps to be performed on a micro LED device. Additionally, some micro LED devices, such as those utilizing an active matrix architecture or a passive matrix architecture, benefit from or require crossover lines for data or power lines and traces. A typical way to achieve such crossover lines is to pattern a dielectric layer between two metal layers with conductive vias to electrically connect the two metal layers. However, this increases the cost of the micro LED device by adding additional steps to the processing of the display substrate.

[0459] Providing electrical crossover lines (e.g., crossover lines 1104 and 1106) by microassembly provides a means to eliminate large area processing steps for providing dielectric layers and second metal layers, thereby reducing costs by providing crossover lines in an area dense configuration on a homogeneous substrate and microassembling the crossover lines in a less dense configuration on a device substrate. Micro LED devices using crossover lines (e.g., crossover lines 1102, 1104, and 1106) assembled in this manner can also benefit from redundancy for defect tolerance in micro LED array devices by providing redundant lines and methods for forming electrical connections across defective open lines.

[0460] This type of layer reduction can be achieved by simple passive devices 1102 (e.g., as described below) Fig.13 The invention is implemented by an integrated device 1104 including a conductive jumper described above or including a crossover and other functionality such as, for example, a CMOS drive circuit and / or nonvolatile memory housed within a structure suitable for microassembly. In some embodiments, the structure suitable for microassembly includes more than one crossover, each crossover having electrical insulation between it and at least one other crossover housed in the structure suitable for microassembly.

[0461] Fig. 12A and 12B is an illustration of an exemplary system that uses a resistor 1206 or a diode 1208, respectively, to facilitate repair by providing information in the form of an electrical characteristic of a redundant micro-assembled micro-LED pixel or sub-pixel in a lighting element or display. In some embodiments, a pixel or sub-pixel is provided with a spare micro-LED 1204 wired by default in parallel with each primary micro-LED 1202 of the pixel or sub-pixel. For example, repair of this embodiment may consist of severing the connection to the shorted micro-LED without providing additional direct-write metal features to connect the spare. In some embodiments, each pixel or sub-pixel that includes a spare micro-LED 1204 wired by default in parallel with the primary micro-LED 1202 also includes a resistor 1206 or a diode 1208 in series with the spare micro-LED 1204, such as Fig. 12A and12B As shown in respectively.

[0462] like Fig. 12A As shown in , in some embodiments, a resistor 1206 is placed in series with the spare micro LED 1204. In this example, the severely shorted primary micro LED 1202 will exhibit an electrical signature (current-voltage relationship) that is less than the resistance of the resistor 1206 in series with the spare micro LED 1204. The severely shorted spare micro LED 1204 will exhibit a resistance that is no less than the series resistor, thereby providing an electrical signature that informs the repair process of which micro LED (primary micro LED 1202 or spare micro LED 1204) needs to be disconnected from the array in order to form a visually perfect micro-assembled micro LED display or lighting element. Fig. 12B As illustrated in , the diode 1208 in series with the spare micro-LED 1204 will notify which micro-LED in the shorted sub-pixel needs repair based on the turn-on voltage characteristics.

[0463] Fig.13 The diagram illustrates cross-sectional views of five different types of electrical connectors 1302, 1304, 1306, 1308, 1310 or "jumpers" suitable for microassembly. In some embodiments, the electrical connector comprises an exposed precious metal surface, including gold, silver, or platinum. In some embodiments, the electrical connector comprises an exposed metal surface, including copper, stainless steel, aluminum, titanium, nickel, or chromium. In some embodiments, the electrical connector comprises a solder, such as PbSn, AgSn, AgSn, or alloys thereof or other solder alloys.

[0464] In some embodiments, the connector (e.g., 1302) is formed of a homogeneous substrate (e.g., silicon, SOI, GaAs, polymer, or glass) and is released from the homogeneous substrate by etching a sacrificial layer. The connector may be transferred to an intermediate stamp or substrate so as to be inverted. The connector may include only metal (e.g., connector 1310).

[0465] In some embodiments, the connector must "jump" or cross over the wires to connect to the point. For example, the jumper wire can be as Fig.38 3804, however, the jumper wire does not necessarily have to conductively contact the wires passing between these pads. In these cases, various designs can be used to ensure that the appropriate wires are crossed ("jumped") and not shorted. For example, connectors 1304 and 1306 include metal and dielectric. The dielectric material can pass over wires that are not intended to be connected by the connector, thereby ensuring that these wires do not short the connector or pads 3802 and 3804. Return to Reference Fig.13, a portion of the connector may be recessed so that the wires between the two jumper wires are not connected by connectors 1304, 1308, and 1310 as shown. Similarly, as illustrated by connector 1308, an insulator may be used to prevent the jumper wire from conductively contacting the two pads (e.g., as shown in FIG. Fig.38 A wire passes between pads 3802 and 3804) as shown in FIG.

[0466] Additionally, the connector may include a combination of more than one of a metal, a polymer, an inorganic dielectric, a semiconductor, and a semi-insulating semiconductor.The connector may have an electrically insulating exposed surface positioned between two exposed conductive regions of the surface.

[0467] Fig.14 1402g, 1402k, 1402m, 1402o, 1402u, and 1402w) and supplemental RGB inorganic micro-LEDs (e.g., micro-LEDs 1402b, 1402d, 1402f, 1402h, 1402j, 1402n, 1402p, 1402r, 1402t, 1402v, and 1402x). In some embodiments, some but not all pixels in this display include multiple R, G, or B micro-LEDs to increase the brightness of the display for ultra-bright flash for lamp or camera flash or daylight viewability. For example, micro-LEDs 1402a, 1402c, 1402e, 1402i, 1402l, 1402o, 1402q, and 1402s are Fig.14 , but omitted. These omitted micro-LEDs may be omitted intentionally or unintentionally. For example, they may not be printed or they may have been removed because they are defective.

[0468] Some of the supplemental micro-LEDs may be a different shape, size (e.g., micro-LED 1402u), or color than other micro-LEDs in the display. A lookup table may be used to facilitate image and lighting quality optimization for all conditions. In some embodiments, the display includes micro-integrated circuits 1406 and micro-sensors 1404, as described above. For example, each pixel may include a micro-integrated circuit 1406 and one or more micro-sensors 1404.

[0469] Fig.15A and 15B is a diagrammatic illustration of a micro-assembled micro-LED display and lighting element architecture. In some embodiments, a display (e.g. Fig.15AThe display shown in ) facilitates repair without built-in redundancy by providing space and circuitry on the substrate for supplementary micro-LEDs. A micro-assembled micro-LED display architecture that can incorporate spare micro-LEDs 1502 after connecting the main micro-LED 1504 array provides a way to produce visually perfect micro-assembled micro-LEDs without requiring supplementary micro-LEDs at every sub-pixel in a fully redundant architecture. Supplementary micro-LEDs (e.g., in ) are provided (e.g., by micro-transfer printing) only in instances where the main micro-LED is defective. Fig.15A Supplementary micro-LEDs may be printed to positions 1502a to 1502d as needed. In some embodiments, connections to positions 1502a to 1502d are already made so that the supplementary micro-LEDs are electrically connected to the display circuitry when printed.

[0470] like Fig. 15B As shown in , in certain embodiments, a display or lighting element architecture includes a light emitter (e.g., a micro-LED 1516) and metal interconnect features 1506a and 1506b (collectively 1506) embedded in or placed on an adhesive or conformal layer 1508 on a display substrate 1512 to which the micro-LED is micro-transfer printed, such that the metal interconnect feature 1506 is exposed on at least one surface of the adhesive or conformal layer 1508 and can be connected to the light emitter 1516.

[0471] The device may include an array of micro-assembled micro-LEDs. Each micro-LED has two contacts on one side (the same side that contacts the adhesive or conformal layer 1508) so that the contacts of the micro-LED are in contact with the metal interconnect features 1506. The spacing of the metal interconnect features 1506a and 1506b and the design of the adhesive layer 1508 and the micro-LEDs 1516 are such that there is an increased tolerance on the placement of each micro-LED 1516, thereby increasing production yields. A portion 1514 of the adhesive layer contacts the bottom side of the micro-LED 1516, thereby fixing the micro-LED in place once it is micro-transfer printed onto the display substrate 1512.

[0472] The micro-LEDs may be tested immediately after assembly, and additional micro-LEDs may be assembled for repair after testing. The architecture may include redundant interconnect features at each sub-pixel to accept additional micro-LEDs for repair. The architecture may include a reflective layer 1510 positioned below at least a portion of the adhesive layer. The reflective layer 1510 may be metallic and may be conductive or serve as an electrical conductor.

[0473] Fig.16 The diagram illustrates micro-assembled micro-LEDs on a non-homogeneous display substrate 1604 that is separate and distinct from the homogeneous source substrate on which or in which the micro-LEDs are formed. Fig.16The architecture of the lighting element shown in facilitates repair without built-in redundancy. A micro-LED array for micro-assembly may have a micro-LED with two terminals 1602a and 1602b (collectively 1602) facing downward (opposite to the contact surface of the micro-LED to be contacted by the transfer element). The micro-LED may have one or more conductive protrusions extending downward from each terminal. In addition, the protrusions may extend beyond other features on the micro-LED. The protrusions (terminals 1602a and 1602b) may contact and penetrate a portion of the metal interconnect features (contact pads) 1608a and 1608b (collectively 1608) to increase electrical connectivity after printing.

[0474] The display substrate 1604 may optionally be provided with a reflective layer or pattern, such as Fig. 15B In some embodiments, display substrate 1604 includes an adhesive or flexible layer 1606 (eg, PDMS) and metal interconnect features 1608 (eg, metal interconnect features having a gold, platinum, tin, copper, or silver surface).

[0475] In some embodiments, an adhesive layer 1606 is deposited on the display substrate 1604, and metal interconnect features 1608 are deposited on top of the adhesive layer 1606 (e.g., by physical deposition, transfer, microassembly, transfer printing, and / or patterning). The micro LED array can be assembled on the display substrate 1604 via a transfer element. The micro LEDs can be adhered to the adhesive layer 1606, establishing electrical connectivity from the contacts 1602 of the micro LEDs to the metal interconnect structures 1608. In some embodiments, the micro LEDs are adhered to the metal interconnect layer 1608. In some embodiments, the formation (e.g., size) of the terminals 1602 is such that it provides increased tolerance for the placement of each micro LED on the display. As Fig.16 As shown in , the micro-LED can be placed further to the left or right side of the non-homogeneous substrate 1604 and the terminals 1602 will still contact their corresponding interconnect features 1608.

[0476] After the micro-LEDs are deposited on the display substrate 1604, the micro-LEDs can be tested, micro-LEDs can be added as needed (e.g., to replace or substitute a defective micro-LED), and metal interconnect features 1608 can be cut as needed (e.g., to disconnect a defective micro-LED). This process can be repeated as needed. These techniques can be used to produce visually perfect micro-LED displays and lighting elements.

[0477] Fig.17is an illustration of an example display 1700 formed by two independent displays occupying the same viewable area 1702. One display can compensate for defects in the other. Independent, coordinated driver chips can control each display. For example, each independent display can have its own row driver and column driver. Fig.17 As shown in FIG. 1 , the first display is driven by column driver 1704 and row driver 1706 and the second display is driven by column driver 1708 and row driver 1710.

[0478] The pixels of the independent displays may occupy the same plane or be positioned on the same surface of the display or they may be spaced apart (eg, separated) by a distance (eg, controlled by placing a dielectric layer between each independent display). Fig.18 1 is an illustration of a stacked micro LED display 1800. Transparent micro LED displays 1802a-1802d (each of which may be a display, such as display 400, as described with respect to FIG. Figure 4 The micro-LEDs described above can be stacked along the vertical dimension. This allows for tunable brightness and can also compensate for defects. For example, instead of positioning the spare micro-LEDs on the same surface or in the same plane as the main micro-LEDs, the spare micro-LEDs can be positioned on a separate surface, thereby forming a stacked display from several independent, fully functional displays. Additionally, stacked transparent micro-LED displays can be used to form 3D displays.

[0479] Fig.19 is composed of three display panels 1902a to 1902c (each of which may be, for example, Figure 4 1 and 2. An illustration of a micro-assembled stacked display 1900 formed by a display of the display 400 described above. Different numbers of display panels can be used to provide various effects and increased clarity. In this example, the micro-assembled display includes redundant RGB inorganic micro-LEDs, driver ICs, sensors, and a transparent substrate. The display uses multiple tiered display panels for defect tolerance, increased brightness, 2.5-dimensional or 3-dimensional information display, or increased resolution.

[0480] Display panels with different resolutions (eg, display panels 2002a and 2002b) may be used to form a stacked display 2000, such as Fig. 20 The displays in the stack can also be different sizes. The micro-LEDs can also be different sizes, colors, or located in different positions. Fig. 20The display 2000 shown in includes two display panels 2002a to 2002b of the same size. The micro-LED on the first display panel 2002a is smaller than the micro-LED on the second display panel 2002b. In addition, the micro-LED on the first display panel 2002a is located in a position different from the micro-LED on the second display panel 2002b. In this example, the display panels 2002a and 2002b have different resolutions. The display panel 2002a includes 24 micro-LEDs (e.g., micro-LEDs 2004a to 2004x) and the display panel 2002b includes only 6 micro-LEDs (e.g., micro-LEDs 2006a to 2006f). In some embodiments, each display panel 2002a and 2002b includes a driver (e.g., a micro-integrated circuit) 2010a and 2010b, respectively. In some embodiments, a single driver is used for each display panel (e.g., 2002a and 2002b) in a stacked display.

[0481] In some embodiments, micro LED emitters are used to form multi-mode displays. Fig.21 21 is an illustration of an example pixel 2100 of a multi-mode display. An emissive micro-LED display 2102 may be combined with a second type of display 2104 (e.g., a reflective display, an electrophoretic display, or a MEMs-based display) to form a multi-mode display. Fig.21 In the example shown in , the second display 2104 is a reflective display. The micro LEDs 2106a-2106f will utilize only a small portion of the pixel area while the reflective component 2104 (for example) may also utilize some area of ​​the area of ​​the pixel 2100. For example, a mobile device such as a cellular phone (including a smart phone) or a tablet computing device can switch between display types, thereby allowing (for example) the micro LED display 2102 to be used when watching a video or viewing a picture, while an ultra-low power "paper-like" display (e.g., an electrophoretic display) or a reflective display (such as the reflective display 2104) can be used for reading.

[0482] In some embodiments, as Fig. 22 As shown in the pixel 2200 illustrated in , the micro-LEDs 2204a-2204f can be placed on top of the reflective element 2202 and do not strongly interfere with the reflective display element given the small size of the micro-LEDs 2204a-2204f.

[0483] As previously discussed, displays (eg, micro-LED displays) may be interleaved with micro-transfer printed sensors and transceivers. Fig.23is an illustration of a pixel 2300 having an integrated circuit 2306 and a micro sensor 2304 connected to micro LEDs 2302a-2302f (e.g., micro LEDs 2302a-2302b form a redundant pair, micro LEDs 2302c-2302d form a redundant pair, and micro LEDs 2302e-2302f form a redundant pair). For example, the display may be interleaved with image capture devices (e.g., optical sensors, photodiodes), infrared sensors (e.g., gesture sensing or IR cameras), temperature sensors (e.g., feedback on the micro LEDs to provide color / brightness correction), and wireless transmission devices. The display may also include power harvesting devices such as solar cells (collecting light), motion energy harvesting (e.g., piezoelectric devices), capacitors to store energy, or antennas for harvesting electromagnetic radiation. The transfer-printed elements interleaved with the display may be printed at different densities (sparseness) depending on the desired function and application. For example, fewer temperature sensors are needed, but each pixel may need an image capture device.

[0484] Fig.24 is an example illustration of the color gamut of human vision and HDTV. The disclosed techniques can be used to improve the color gamut of a display to more closely match the color gamut of human vision.

[0485] like Fig.25 , the micro LED display may include micro LEDs of various colors to, among other things, improve the color gamut of the display. In addition to standard red micro LEDs 2502a-2502b, blue micro LEDs 2502e-2502f, and green micro LEDs 2502g-2502h, in some embodiments, the micro LED display includes yellow micro LEDs 2502c and 2502d (for example, as in Fig.25 2502c emits a different shade of green light than 2502d). This allows for an improved color gamut (e.g., more achievable colors). The display may also include a micro integrated circuit 2506, a micro sensor 2504, or other semiconductor elements, as described above.

[0486] Fig.262 is an illustration of an example pixel 2600 for use in a micro-assembled inorganic micro-LED array to create a visually perfect device. The pixel 2600 includes six sub-pixels 2608a-2608f, each sub-pixel having a different color (e.g., one sub-pixel 2608a has a red micro-LED 2602a, another sub-pixel 2608b has a different red micro-LED 2802b; one sub-pixel 2608c has a green micro-LED 2602c, another sub-pixel 2608d has a different green micro-LED 2602d; one sub-pixel 2608e has a blue micro-LED 2602e and one pixel 2608f has a different blue micro-LED 2602f). For example, the pixel 2600 may include six sub-pixels 2608a-2608f, each sub-pixel having a micro-LED having a respective peak of output intensity up to 450nm, 460nm, 530nm, 540nm, 650nm, and 660nm. A lookup table may be used to compensate for pixel non-uniformity.

[0487] Figures 27A to 27B is a graphic illustration of two micro-assembled inorganic micro-LED array strategies used to produce visually perfect devices. Fig.27A The display 2700 shown in FIG. 2 uses two micro-LEDs ( 2702a and 2702b ) per sub-pixel 2704 . Fig.27B The display 2750 shown in utilises more pixels per unit area (e.g., 2756a-2756d) and fewer sub-pixels and / or micro-LEDs per pixel. Fig.27B In the example shown in , there is only one micro-LED 2752 per sub-pixel 2754, however there are two or more pixels (in this example, 4 pixels; 12 sub-pixels) for each visually discernible area of ​​the display. In the event that one micro-LED is missing in the display, the neighboring pixels use information from the lookup table to compensate. For example, if micro-LED 2752a is missing, then micro-LED 2752b can be used to compensate for the missing micro-LED.

[0488] Fig.282800 prior to connection. In some embodiments, the array of micro-assembled micro-LEDs 2802a to 2802f can be illuminated and the photoluminescence can be observed to identify defective micro-LEDs (e.g., 2802a and 2802e) prior to connection. This can be used to trigger a physical repair, adding additional micro-LEDs to the sub-pixels containing defective micro-LEDs identified by the photoluminescence test. In this example, micro-LEDs 2802a and 2802e are defective and are removed. In some embodiments, therefore, only micro-LEDs 2802b, 2802c, and 2802f will be wired. In other embodiments, 2802d is also wired. Fig.28 Also illustrated is a scenario in which micro-LED 2802d is defective and additional micro-LEDs 2802c are printed to compensate for this defective micro-LED 2802d.

[0489] Fig.29 is a diagrammatic illustration of using chips of color conversion materials (e.g., polyhedra such as vertices) to implement color conversion in micro-assembled micro-LED displays and lighting elements. In some embodiments, the displays and lighting elements require full RGB capability and / or colors other than the direct emission wavelengths of their constituent micro-LEDs.

[0490] One method for achieving this color conversion is by using microassembly techniques to place arrays of micro LEDs 2904a and 2904b over, on, or in contact with corresponding arrays of color conversion materials, for example, by forming recesses 2902a-2902h in a display substrate 2906 that is at least partially transparent and filling the recesses with phosphors and other color conversion materials. Color conversion materials include phosphor-containing gels or resins, phosphor ceramics, and single crystal phosphors. Other color conversion materials include direct bandgap semiconductors, such as those that, in some embodiments, include portions of a quantum well and surface-passivated epitaxial stack.

[0491] In an alternative color conversion approach, a chip of a color converting material, such as a direct bandgap semiconductor, is microassembled on a display substrate, and at least a portion of an array of micro-LEDs is assembled over the chip.

[0492] In some embodiments, the device is designed so that most or all of the light emitted from the micro-LEDs is emitted downward through the transparent display substrate and optionally through the color conversion material. This property imparts valuable characteristics to the device, which, for example, has such a property as in a display or lighting element that is nearly transparent from one direction and a bright light source or information display from the opposite direction. This property can be achieved by forming a reflective structure that completely or nearly completely covers one side of the micro-LEDs (e.g., the "top" side of the micro-LEDs), where the micro-LED contacts, array connection metal, and / or supplemental mirror structures are formed on the display substrate.

[0493] In an alternative approach to color conversion, a color converting layer is formed on top of the micro-LEDs or at least partially surrounds the micro-LEDs on more than one side of the micro-LEDs.

[0494] Fig. 30A and 30B are images and diagrammatic illustrations of an apparatus for using self-aligned dielectrics for micro-assembling micro LED displays and lighting elements. In some embodiments, it is advantageous to reduce the number of alignment steps on a display substrate for micro-assembling micro LED displays or lighting elements.

[0495] In some embodiments, a micro-LED comprising some material that is substantially transparent to a specific wavelength is assembled on a display substrate that is also transparent to the same specific wavelength. The micro-LED has one or two metal contacts on the side of the micro-LED that is located opposite the interface between the micro-LED and the display substrate. The micro-LED optionally also comprises a dielectric material (e.g., silicon oxide or silicon nitride) covering a portion of the side of the micro-LED opposite the display substrate. Before forming a connection to the micro-LED, in some embodiments, it is beneficial to provide an insulating layer around the perimeter of the micro-LED, thereby avoiding unwanted electrical shorts. The insulating layer is formed by depositing a layer of a photodefinable dielectric (e.g., BCB, polyimide, PBO, epoxy, or silicone), thereby exposing the photosensitive dielectric to light, causing light to shine from under the display substrate, and cross-linking the photodefinable material (except for the area above the two metal contacts), thereby electrically insulating the perimeter of the micro-LED before forming a connection.

[0496] In some embodiments, a camera with a spectral response that matches human vision can be used to define a lookup table for use with a micro-assembled micro-LED display. Displays using micro-assembled micro-LEDs benefit from pixel-to-pixel brightness uniformity and color consistency. The epitaxial and micro-fabrication processes that produce micro-LEDs typically produce micro-LEDs with a range of brightness and a range of output spectra. In some embodiments, a display using a micro-LED assembly benefits from a lookup table characterized by the output of each sub-pixel (e.g., allowing the display to drive each individual sub-pixel according to the relationship between brightness and the current of that sub-pixel), thereby providing the information needed to accurately reproduce images and colors as if the device's micro-LEDs did not have non-uniformities in color and brightness. In addition, the lookup table can take into account the relationship between brightness, color, and efficiency of the human visual response.

[0497] In some embodiments, a camera and optical filter having a spectral response that matches the spectral response of the human eye are used to generate a lookup table for a micro LED display. In some embodiments, a camera and optical filter having a spectral response that matches the spectral response of human vision blue response, a camera and optical filter having a spectral response that matches the spectral response of human vision green response, and a camera and optical filter having a spectral response that matches the spectral response of human vision red response are used to generate a lookup table for a micro LED display.

[0498] In some embodiments, an array of microscale functional elements is interleaved with an array of microscale control elements. In some embodiments, an array of assembled inorganic microscale functional devices is integrated with an interleaved array of assembled microscale control elements. The control elements may include microscale silicon integrated circuit devices that are integrated and interleaved with microscale devices by a microassembly method. In some embodiments, the microassembly method is transfer printing with an elastomeric stamp, an electrostatic head, and / or a vacuum chuck-based assembly tool.

[0499] The assembled micro-scale functional element may be a micro-light emitting device such as a light emitting diode (LED), a vertical cavity surface emitting laser (VCSEL), or an edge emitting laser. The assembled micro-scale functional element may be a sensing device such as a photodiode, a radiation sensor, a temperature sensor, and a motion sensor. The assembled micro-scale functional element may be an energy harvesting or energy conversion device. The assembled micro-scale functional element may be an actuator device.

[0500] A single microscale control element can control a cluster or array of functional elements. In some embodiments, the control element is connected to the cluster of functional elements through a network of wires that fan out from the control element to each functional element. In some embodiments, the wiring is made of patterned deposited thin film metal (e.g., Al, Cu, Mo, or Au).

[0501] Microscale control integrated circuits may include a variety of functionalities. Control elements may include memory, both digital and analog circuits, sensors, signal processing circuits, and / or optical transceivers (e.g., providing optical input to and output from control elements). Functional element clusters and individual control elements may operate as independent units within a larger cluster array. Each functional element cluster may operate as an independent display.

[0502] Fig.31 is an illustration of an example 4×4 array 3100 of functional elements 3102a to 3102p (collectively 3102) controlled by a single microassembled integrated circuit 3104. The functional elements 3102 may be connected to the control elements 3104 by a single thin film metallization process. In some embodiments, the control elements 3104 and the functional elements 3102 are positioned in the same plane or on the same surface. The connection wiring fans out away from the control elements 3104 and may be connected to each of the functional elements 3102, such as Fig.31 as shown in .

[0503] Fig.32 is an array of six 4×4 functional elements (each functional element is controlled by a single micro-assembled integrated circuit) (e.g., Fig.31 Arrays of control elements can be interleaved within arrays of functional elements using microassembly.

[0504] Fig.33 is an illustration of an example array 3300 that uses a control element 3302 to control different types of functional elements. For example, the array 3300 may include sixteen pixels 3306a to 3306p (collectively 3306, but other numbers of pixels may be used). Each pixel 3306 may include a red micro-LED 3304a, a blue micro-LED 3304b, and a green micro-LED 3304c. The control element 3302 may process signals from or read out signals from the sensing functional elements and also control or read in signals to the functional array elements. Thus, the array device may be multifunctional and may perform many tasks on the same surface or in the same plane or array area (e.g., a hyperspectral focal plane array). The array may use a single metal level and a single control element for functional clustering.

[0505] Fig.34 is an illustration of a display 3400 formed using microassembly. Each integrated circuit pixel cluster can act as an independent display and each functional element cluster can operate independently of the control element. For example, a small portion of the entire device can be powered on in use, and the rest of the array device (display, for example) can remain powered off. Fig.35is an illustration of an example display 3500 in which a user has selected to turn on only a portion of the overall device. Fig.36 is an illustration of an example display 3600 in which a user has chosen to turn on only a portion of the entire device that is in a non-standard shape (eg, a shape that is not rectangular).

[0506] Fig.37 is an illustration of an example array 3700 with wireless data or power input. The control element can be connected to an integrated antenna 3702. Thus, the display block can have data or power streamed to an array of functional devices (e.g., a display) using wireless electromagnetic transmission.

[0507] Fig.38 is a diagrammatic illustration of a control element designed to have built-in redundancy. For example, additional control chips may be printed per element cluster (as described above). Micro-assembled jumpers or crossovers may be used to provide a means to electrically connect spare control elements (e.g., connecting pad 3802 to pad 3804). Thus, as discussed above, a sparsely populated multifunction array may provide space for spare devices that implement additional functionality and may use micro-assembled low-cost jumpers to connect to the spare devices.

[0508] Fig.39 is an illustration of an array 3900 having a control device 3904 with built-in memory 3902. The control device 3904 may be an integrated circuit control device including embedded memory. This implements a refresh-on-demand power saving display for static images.

[0509] Fig.40 is an illustration of a microassembled micro LED display 4000 with a microassembled temperature sensing element 4002. Microassembly technology facilitates the formation of a microassembled micro LED display including microassembled micro LEDs 4004a and 4004b (collectively 4004) and a microassembled IR or temperature sensing device 4002. A display including temperature or IR sensing can provide desirable data input capabilities, for example, a touch-free human-machine interface. In some embodiments, the IR or temperature sensing device includes a low bandgap semiconductor (e.g., InGaAs, InGaAsSb, HgCdTe), a thermoelectric material (e.g., lithium tantalate or lithium niobate), a thermopile, and other devices that respond electrically to a temperature gradient or temperature change. In some embodiments, it is advantageous for the display to include one type of temperature sensing device. In some embodiments, the display includes more than one type of temperature sensing device.

[0510] In some embodiments, the microassembled display includes one or more of microassembled micro-LEDs of several colors, several different types of microassembled IR or temperature sensing devices, microassembled passive electrical components, or microassembled control or memory elements. In some embodiments, the number of sensing elements is less than the number of micro-LEDs in the display. In some embodiments, the number of sensing elements is equal to or greater than the number of micro-LEDs.

[0511] In some embodiments, the disclosed technology provides a passive matrix display using inorganic micro-LEDs and methods of making displays. Similarly, in some embodiments, the disclosed technology provides an active matrix display using inorganic micro-LEDs and methods of making displays.

[0512] Fig.41 An image of a complete passive matrix inorganic light emitting diode (LED) display is shown in FIG. This display includes a 360×90 array of microscale red LEDs. The micro-LEDs used in the displays disclosed herein are prepared on their homogeneous substrate, partially removed from the substrate, and the position of the micro-LEDs on the homogeneous substrate is maintained by tethers (e.g., a single, off-center tether for each LED), and then microtransfer printed using a viscoelastic elastomeric stamp. The micro-LEDs are formed on their homogeneous substrate at a resolution of approximately 3000 micro-LEDs per square inch. In some embodiments, the micro-LEDs are formed at a resolution of up to 10 per square centimeter. 6 or 10 8 The resolution of each micro-LED is formed on its homogeneous substrate.

[0513] The illustrated display is designed to support a 128×128 pixel array using red, green, and blue LEDs. Also, in this example, there are two sites for each color LED (red, green, and blue) in each pixel so that redundancy schemes such as those described herein can be implemented (if desired). In this demonstration, red LEDs are filled into the green and blue sub-pixel sites. Micro-LEDs of other colors can also be used in addition to red in order to produce a full-color display. The pixel size is 99×99 microns, as shown in FIG. Fig.42 As shown in , this is equivalent to 256 pixels per inch. The emissive area is 11.88 mm x 8.91 mm. The size of the glass substrate supporting the display is approximately 25 mm x 25 mm.

[0514] Fig.43is an optical micrograph of a single pixel within a display. The micro-LEDs are connected to the metal rows and columns using thin-film metal interconnects. The topmost metal (e.g., Metal 2) is connected to the lower metal (e.g., Metal 1) through vias etched into a dielectric layer deposited above Metal 1. The micro-LEDs emit light in both (all) directions, however, the metal contacts on the micro-LEDs reflect much of the light downward through the glass substrate.

[0515] Fig.44 is an image of a complete display substrate (glass substrate) with passive matrix displays on it. Sixteen displays are printed onto each 150 mm glass wafer. In some cases, less than 16 displays are printed. Fig.45 is an optical micrograph of a display's pixel array.

[0516] Fig.46 It is used to manufacture passive matrix inorganic light emitting diode displays (e.g. manufactured on 150 mm glass wafers (0.7 mm thick) Figures 47A to 47B 48A-48B). As discussed above, other substrates such as sapphire and plastic can also be used as display substrates. The display substrate can be thinner (e.g., 0.5 mm to 1 mm thick).

[0517] The first metal level is deposited and patterned on the wafer surface (4602) using metal physical vapor deposition and photolithography techniques. Specifically, a negative-acting photoresist is exposed and developed to form a lift-off template, a Ti / Al / Ti metal stack is deposited using electron beam evaporation, and then the patterned metal layer is completed by removing the lift-off template. Metal 1 includes a stack of aluminum (2000A) and titanium (250A). The purpose of the topmost titanium is to protect the aluminum from passivation chemistry later in the process flow.

[0518] A silicon nitride dielectric layer is deposited on the wafer surface (4604) to form an electrical insulating layer between Metal 1 and Metal 2. Next, a thin polymer layer is spun onto the wafer surface using a wafer spinner (4606). Here, a photosensitive negative-acting semiconductor grade epoxy (Dow Intervia 8023) from Dow Chemical Co., Midland, Michigan, is used. The solvent is removed from the polymer using a thermal treatment. Specifically, a soft bake is performed on a hot plate at 140 degrees Celsius for 4 minutes, followed by a bake in an oven at 90 degrees Celsius in flowing nitrogen for 30 minutes.

[0519] Next, the microscale inorganic LEDs are micro-transfer printed onto the surface of the polymer (4608). Micro-transfer printing is performed using a printing tool. A viscoelastic elastomer stamp is used to facilitate the printing process. The transfer process utilizes motion-adjustable adhesion between a solid (LED) and a viscoelastic elastomer surface. To pick up the LED, the tool moves the stamp quickly away from the source surface, resulting in an effective increase in adhesion between the elastomer and the chip. During printing, the printing tool moves the stamp slowly away from the destination surface, thereby leaving the LED on the target surface (e.g., a polymer surface). In addition, the printing step is assisted by imparting lateral shear movement to the stamp during the transfer process. The stamp transfers a 120×90 micro LED array to the display. To complete a 360×90 display, three printing operations are performed.

[0520] To make a full color display (120RGB×90), three separate printing operations are required, one for the red light emitters, one for the green light emitters, and one for the blue light emitters. For redundancy, additional LEDs can be printed. In this example, six LEDs are printed into each pixel, such as Fig.43 As shown in . Therefore, this configuration can implement redundant micro-LEDs.

[0521] Fig.43 The pixel in shows an example of six micro-LEDs within a single 99×99 micron pixel. In this example, the full LED array is printed in six transfer operations. For the display shown here, only three sub-pixel sites are utilized (e.g., driven by a driver chip).

[0522] After transferring the micro-LEDs, the polymer is first exposed to UV radiation and then cured in an oven at 175 degrees Celsius for 3 hours under flowing nitrogen (4610). UV exposure of the polymer is an important step to prevent the micro-LEDs from moving during oven curing of the device.

[0523] Next, vias (windows) are formed through the dielectric layers (both polymer and silicon nitride) to expose the surface of Metal 1 (4612). This process is performed using standard photolithography (exposure and development of positive acting photoresist) and reactive ion etching of the polymer and silicon nitride layers. The topmost titanium on the aluminum is used to prevent the aluminum from passivating during the reactive ion etching step.

[0524] Next, a second metal (Metal 2) is deposited and patterned (4614). The purpose of Metal 2 is to contact both the anode and cathode of the micro LED and to connect the anode to Metal 1 through vias. This process is accomplished by first patterning a lift-off template in negative-acting photoresist, then depositing the metal stack (Ti / Al / Ti / Au), and finally stripping the photoresist mask to leave the patterned metal wiring.

[0525] The wafer is sawn into individual displays using a dicing tool (e.g., a Dico dicing tool) 4616. Prior to dicing, the display wafer is coated with a protective photoresist layer, and this protective photoresist layer is solvent stripped from each individual display die after dicing.

[0526] After the individual displays are diced from the wafer, the passive matrix driver ICs are bonded to receiving pads (4618) on the surface of the glass wafer. This is accomplished using a standard "chip on glass" bonding process, where an anisotropic conductive film (ACF) is used to make the electrical connection between the metal (Metal 2) pads on the glass and the metal pads on the driver IC.

[0527] Next, a flexible printed circuit (cable) is attached to the display (4620) using "flex-on-glass" technology. Here, an ACF film is used to electrically interconnect the flexible printed circuit to the metal (Metal 2) pads on the display glass.

[0528] In this example, an FPGA driver board is used to send the input (picture) into the driver chip and ultimately into the display. A flexible printed circuit connects the driver chip and display to the FPGA driver board.

[0529] Figures 47A to 47B and 48A to 48B are images of working displays. Fig.47A is a passive matrix inorganic light emitting diode display image and Fig.47B This is a magnified image of a passive matrix inorganic light emitting diode display. Fig.48A is another image of a passive matrix inorganic light emitting diode display and Fig.48B Differently magnified images of a passive matrix inorganic light emitting diode display. Figures 49A to 49G is an image demonstrating the transparency of the display. Ambient light is blocked by the metal wires and small LEDs, and the remaining layers are transparent.

[0530] Fig.50is a photomicrograph of an exemplary micro-LED display wired in a passive matrix configuration. A micro-assembled LED display uses multiple micro-LEDs transferred from an epitaxial substrate to a display substrate (e.g., to a display substrate that is non-homogeneous to the LEDs, such as plastic or glass) to produce a display. The disclosed display architecture establishes contacts from the "top" of each LED to the two terminals of each LED. The conductive lines and spaces (or other shapes) that contact the anode of the LED are laterally separated from the conductive structures that contact the cathode of the same LED. In this embodiment, the LED also has electrically contactable terminals (e.g., cathode and anode) that are laterally separated from each other. This configuration allows interconnections to be established to the LEDs using panel processing or other large area processing in which the lines and spaces are relatively coarse and inexpensive to form on a per-area basis (e.g., 2 micron lines and spaces to 2 mm lines and spaces). For example, Fig.50 The micro LED display shown in uses 2.5 μm and 5 μm conductive lines for row lines 5004a-5004c, column lines 5006a-5006b, and interconnects 5008a-5008b.

[0531] In some embodiments, the electrically contactable terminals on the micro-LED are formed to occupy as much of the footprint of the LED area as possible. Therefore, in order to achieve lateral separation of the two terminals of the micro-LED, in some embodiments, the LED has a length that is sufficiently longer than its width. In some embodiments, the LED uses fine lithography (for example, wafer-length lithography with features ranging from 100 nm to 20 microns) to reduce the separation distance between the terminals.

[0532] For example, if Fig.50 LEDs 5002a to 5002f shown in are rectangular micro-LEDs. Specifically, in this example, the LEDs have a width of 3.5 μm and a length of 10 μm. In certain embodiments, the elongated geometry is advantageous, including when the terminals of each LED are located on one side of the LED. Among other things, the elongated geometry of the LEDs coupled with large terminal electrodes provides ease of placement (e.g., reducing the accuracy required to place each LED). In certain embodiments, the length to width ratio is greater than 2, for example, in a range from 2 to 5. In certain embodiments, the LEDs described herein have at least one of a width, length, and height in the following ranges: from 2 μm to 5 μm, from 5 μm to 10 μm, from 10 μm to 20 μm, or from 20 μm to 50 μm.

[0533] In certain embodiments, column electrodes (e.g., conductive lines 5006a to 5006b) are formed on a substrate. An insulating layer is applied over the column electrodes. Holes 5010a to 5010d are formed in the column electrodes to expose the column electrodes. LEDs 5002a to 5002f are micro-transfer printed onto the insulating layer. Conductive material may be applied in a single level to form row electrodes 5004a to 5004c and interconnects (e.g., 5008a to 5008b) to the column electrodes. Row electrodes 5004a to 5004c electrically contact a first terminal on a corresponding LED and interconnects (e.g., 5008a to 5008b) electrically connect a second terminal on a corresponding LED to a corresponding column electrode. Thus, LED terminals (which are located on the same face of the LED) may be connected on a single level. For example, the connection of a micro-LED may use a single photomask and metal level (e.g., a single level) to establish connections to two terminals of the LED.

[0534] Fig.51 is a diagrammatic illustration of an example printed LED wired in a passive matrix configuration. Row electrodes 5104 and interconnects 5108a-5108b are formed on a single level. Interconnects 5108a-5108b are electrically connected to a corresponding column electrode 5106a-5106b. Fig.51 As shown in , the interconnections between interconnects 5108a-5108b and column electrodes 5106a-5106b, respectively, are not insulated because holes 5110a and 5110b are formed in the insulation, as discussed above. In contrast, the interconnections between row electrodes 5104 and column electrodes 5106a-5106b are insulated.

[0535] Fig.52 is an optical micrograph of a single LED 5202 wired in a passive matrix configuration (e.g., Figure 1 ). LED 5202 includes a first terminal 5210 and a second terminal 5212. Reducing the lateral separation between terminals 5210 and 5212 of the LED and increasing the size of terminals 5210 and 5212 within the constraints of the size of the LED increases the tolerance for alignment and lithography errors between the assembled micro-LEDs and the relatively thick conductive lines (5204, 5206, and 5208) used to interconnect them on the display substrate.

[0536] Figures 53A to 53B is an illustration of an example architecture of a micro-LED suitable for contacting two terminals from one side of the LED. Fig.53A is a plan view of LED 5300 and Fig.53B is a cross-sectional view of LED 5300. Fig.53A and 53B, terminals 5302a and 5302b cover a large portion of the top of LED 5300 and both terminals 5302a and 5302b are located on the top surface of LED 5300. The gap between the electrodes is minimized (e.g., a distance of 100nm to 100 microns), as discussed above. This configuration allows the interconnection to the LED to be established using panel processing or other low-resolution large-area processing in which line and space formation on a per-area basis is relatively coarse and inexpensive (2 micron line and space to 2 mm line and space). In some embodiments, to achieve lateral separation of the two terminals of micro-LED 5300, LED 5300 has a length that is sufficiently longer than its width. In some embodiments, the LED uses fine lithography (for example, wafer length lithography with features ranging from 100nm to 20 microns) to reduce the separation distance between the terminals.

[0537] The active layer is formed on the lateral conductive layer. The dielectric material is deposited on the active material and on one side of the active layer and the lateral conductive layer, such as Fig.53B Terminal 5302a is connected to the active layer and terminal 5302b is connected to the lateral conductive layer.

[0538] In certain embodiments, the LEDs emit a substantial majority of the light externally to the downward emitter. In such embodiments, the electrically contactable / conductive terminals may be formed in a reflective metal including gold, silver, nickel, aluminum, and alloys thereof. In contrast, in downward emitting embodiments, the lateral fabric structures are formed in a material transparent to the light emitted from the LEDs, such as a semiconductor with a suitable bandgap or absorption edge selected to minimize absorption in the lateral conductive layer. A mirror (not shown here) may be formed above the LEDs to further reflect light from the LEDs downward.

[0539] In certain embodiments, the LED is configured to emit a substantial portion of its externally emitted light upward. In such embodiments, the electrically contactable / conductive terminals are formed in a transparent material including transparent conductive oxides, ITO, ZnO, carbon nanotube films, and fine metal meshes. Also in upward emitting embodiments, the lateral architectural structures are formed in a material transparent to the light emitted from the LED, for example a semiconductor with a suitable bandgap or absorption edge selected to minimize absorption in the lateral conductive layer. In these embodiments, the lateral conductive layer may also include an optically reflective layer including a dielectric mirror, a metallic mirror, and / or a material with a high refractive index to promote total internal reflection. An optically reflective material or portion of a display substrate may be provided to reflect light from the LED upward.

[0540] Figures 54A to 54E The diagram illustrates an embodiment of a light emitting diode structure according to an embodiment of the present invention. Fig.54A, a first electrical contact 5402 is located on a first side of a semiconductor element 5406 and a second electrical contact 5404 is located on an opposite side of the semiconductor element 5406. In this example, the first electrical contact 5402 is accessed from the top when the semiconductor element 5406 is printed onto a display substrate. The first electrical contact 5402 is formed so that a portion of it extends beyond the edge of the semiconductor element 5406, thereby enabling access to the first electrical contact 5402 from the same side of the structure as the second electrical contact 5404 when the structure is printed onto a display substrate 5410. This can be advantageous when printing on a display substrate 5410 because both the first electrical contact 5402 and the second electrical contact 5404 can be accessed in a common set of photolithography steps for connection.

[0541] Fig.54B The display substrate 5410 is shown in FIG. Fig.54A 5406, wherein the first electrical contact 5402 contacts the first contact pad 5452 on the display substrate 5410. An electrical connection 5450 may be formed to the second electrical contact 5404 of the printed semiconductor structure. The passivation layer 5419 prevents unwanted conduction from the first conductive line 5450 and the second conductive line 5452 to the semiconductor element 5406.

[0542] Fig.54A The structure illustrated in can be formed by removing a portion of the semiconductor element 5406 (eg, by etching) using a photolithography process so that a portion of the first electrical contact 5402 is exposed (eg, accessible from the same side as the second electrical contact 5404).

[0543] Fig.54C An alternative structure is illustrated in which both the first electrical contact 5402 and the second electrical contact 5404 are positioned on the same side of the semiconductor element 5406. This structure is also made by removing a portion of the semiconductor element 5406, however, the removal of semiconductor material occurs where the portion is completely etched through the semiconductor element 5406 (e.g., Fig.54A ), thereby leaving behind a cantilever extension 5408 of the semiconductor element 5406. In one embodiment, the cantilever extension 5408 is doped differently than the remainder of the semiconductor element 5406. For example, this allows the cantilever extension 5408 to be more conductive or better prevent light emission while the remainder of the semiconductor element 5406 is doped to emit light in response to current flow between the first electrical contact 5402 and the second electrical contact 5404.

[0544] Fig.54D The diagram illustrates an alternative structure for a light emitting diode. This structure is similar to Fig.54C, however, the first electrical contact 5402 is thicker so that the first electrical contact 5402 and the second electrical contact 5404 have top surfaces in the same plane or contact a common surface. In some embodiments, this is advantageous because the light emitting diodes can be printed onto the display substrate with the coplanar connection pads already formed. This allows the light emitting diodes to be electrically connected to the display circuitry when they are printed onto the display substrate 5410.

[0545] After forming cantilever extension 5408, first electrical contact 5402 is formed on cantilever extension 5408 (eg, by photolithography). In certain embodiments, both first electrical contact 5402 and second electrical contact 5404 are formed simultaneously or sequentially.

[0546] The above article about Fig.54A , Fig.54C and 54D The described structures can be printed on the display substrate 5410 using a printing process employing a stamp (eg, an elastomeric stamp) to form a display. Fig.54B The display substrate 5410 is shown in FIG. Fig.54A A light emitting diode, wherein the first electrical contact 5402 contacts the first contact pad 5452 on the display substrate 5410. An electrical connection 5450 to the second electrical contact 5404 of the printed semiconductor structure may be formed. The passivation layer 5419 prevents unwanted conduction from the first conductive line 5450 and the second conductive line 5452 to the semiconductor element 5406. Similarly, Fig.54E The display substrate 5410 is shown in FIG. Fig.54C The light-emitting diode and the wires 5450, 5452 formed thereby.

[0547] Having described specific embodiments, it will now be apparent to those skilled in the art that other embodiments incorporating the concepts of the present invention may be used. Therefore, the present invention should not be limited to specific embodiments, but should only be limited by the spirit and scope of the appended claims.

[0548] Throughout the descriptions where devices and systems are described as having, containing, or including specific components, or where processes and methods are described as having, containing, or including specific steps, it is further contemplated that there are devices and systems of the disclosed technology that consist essentially of or consist of the described components, and that there are processes and methods according to the disclosed technology that consist essentially of or consist of the described processing steps.

[0549] It should be understood that the order of steps or the order in which certain actions are performed are not important as long as the disclosed technology remains operable. In addition, two or more than two steps or actions may be performed simultaneously.

Claims

1. A micro LED display comprising: a display substrate that is at least partially transparent and includes an array of recesses; an array of color conversion structures disposed on and in direct contact with the display substrate, each color conversion structure comprising a color conversion material that converts relatively high frequency light to relatively low frequency light, wherein the color conversion material is located in the array of recesses; an array of micro-LEDs separate from the color conversion structures, each micro-LED in the array of micro-LEDs being disposed on and in direct contact with a color conversion material of a corresponding one of the color conversion structures in the array of color conversion structures, whereby the color conversion material is between the micro-LED and the display substrate, and wherein the color conversion material is further disposed on more than one side of the micro-LED at least partially surrounding the micro-LED; as well as One or more reflective structures substantially cover a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate.

2. The display of claim 1 , wherein the micro-LEDs are disposed on the color conversion material on a side of the color conversion material opposite the display substrate such that most or all of the light emitted from the micro-LEDs is emitted downwardly through the color conversion material and the display substrate.

3. The display of claim 1, wherein the one or more reflective structures comprise an array of connected metal or micro-LED contacts.

4. The display of claim 1, wherein the color conversion material comprises at least one component selected from the group consisting of: a phosphor-containing gel or resin, a phosphor ceramic, or a single crystal phosphor.

5. The display of claim 1 wherein the color conversion material is a chip of a direct bandgap semiconductor.

6. The display of claim 1 including a supplemental mirror structure on the display substrate.

7. The display of claim 1 wherein each micro-LED has an LED substrate separate from the display substrate.

8. The display of claim 1 wherein the micro-LEDs are formed in a homogenous substrate distinct and separate from the display substrate.

9. The display of claim 1 , wherein the display substrate has a thickness of from 5 microns to 10 microns, or from 10 microns to 50 microns, or from 50 microns to 100 microns, or from 100 microns to 200 microns, or from 200 microns to 500 microns, or from 0.5 mm to 1 mm, or from 1 mm to 5 mm, or from 5 mm to 10 mm, or from 10 mm to 20 mm.

10. The display of claim 1, wherein each micro-LED has a width from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm.

11. The display of claim 1 , wherein each micro-LED has a length from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm.

12. The display of claim 1 , wherein each micro-LED has a height from 2 µm to 5 µm, or from 4 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm.

13. The display of claim 1, wherein each micro-LED has an anode and a cathode disposed on the same side of the respective micro-LED.

14. A display according to claim 13, wherein the anode and cathode of the corresponding light emitter are horizontally separated by a horizontal distance, wherein the horizontal distance is from 100 nm to 500 nm, or from 500 nm to 1 micron, or from 1 micron to 20 microns, or from 20 microns to 50 microns, or from 50 microns to 100 microns.

15. The display of claim 1, comprising one or more electrodes disposed on a same side of the display substrate, and wherein the micro-LEDs are electrically connected to the one or more electrodes.

16. The display of claim 1, comprising one or more control circuits disposed on the same side of the display substrate, and wherein each micro-LED is electrically connected to one of the control circuits.

17. The display of claim 1 wherein the micro-LEDs comprise at least a partial tether.

18. A micro LED display comprising: a display substrate comprising an array of recesses; a micro LED array located on and in direct contact with the display substrate; as well as an array of color conversion structures separate from the micro-LED structures, wherein each color conversion structure includes a color conversion material that converts relatively high frequency light to relatively low frequency light, wherein the color conversion material is located in the array of recesses, wherein the color converting material of each color converting structure in the array of color converting structures is disposed directly on a corresponding one of the micro-LEDs in the array of micro-LEDs, whereby the micro-LED is between the color converting structure and the display substrate, and wherein the color converting material is further disposed on more than one side of the micro-LED at least partially surrounding the micro-LED; as well as One or more reflective structures substantially cover a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate.

19. A micro LED display comprising: a display substrate that is at least partially transparent and includes an array of recesses; an array of color conversion structures disposed on the display substrate, each color conversion structure comprising a color conversion material that converts relatively high frequency light to relatively low frequency light, wherein the color conversion material is located in the array of recesses; an array of micro-LEDs separate from the color conversion structures, each micro-LED in the array of micro-LEDs being disposed on and in direct contact with a corresponding one of the color conversion structures in the array of color conversion structures, whereby the color conversion structure is between the micro-LEDs and the display substrate, and wherein the color conversion material is further disposed on more than one side of the micro-LED at least partially surrounding the micro-LED; as well as One or more reflective structures substantially cover a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate.

20. A micro LED display comprising: a display substrate that is at least partially transparent and includes an array of recesses; an array of color conversion structures disposed on and in direct contact with the display substrate, each color conversion structure comprising a color conversion material that converts relatively high frequency light to relatively low frequency light, wherein the color conversion material is located in the array of recesses; an array of micro-LEDs separate from the color conversion structures, each micro-LED in the array of micro-LEDs being disposed on and in direct contact with the color conversion material of a corresponding one of the color conversion structures in the array of color conversion structures, whereby the color conversion material is between the micro-LED and the display substrate; one or more reflective structures that substantially cover a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate, and The color conversion material is a direct bandgap semiconductor chip, wherein the micro-LED comprises at least a partial tether, and Each micro-LED has: (i) a width of from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm, (ii) a length of from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm, (iii) from 2 µm to 5 µm, or from 4 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm in height, or (iv) Any combination of (i), (ii) or (iii).

21. A micro LED display comprising: a display substrate and including an array of recesses; a micro LED array located on and in direct contact with the display substrate; an array of color conversion structures separate from the micro-LED structures, wherein each color conversion structure includes a color conversion material that converts relatively high frequency light to relatively low frequency light, wherein the color conversion material is located in the array of recesses; one or more reflective structures that substantially cover a side of the micro-LED opposite the display substrate such that the micro-LED reflects emitted light toward the display substrate, and wherein the color converting material of each color converting structure in the array of color converting structures is disposed directly on a corresponding one of the micro-LEDs in the array of micro-LEDs, whereby the micro-LED is located between the color converting structure and the display substrate, The color conversion material is a direct bandgap semiconductor chip, wherein the micro-LED comprises at least a partial tether, and The micro-LED has: (i) a width of from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm, (ii) a length of from 2 µm to 5 µm, or from 5 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm, (iii) from 2 µm to 5 µm, or from 4 µm to 10 µm, or from 10 µm to 20 µm, or from 20 µm to 50 µm in height, or (iv) Any combination of (i), (ii) or (iii).

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