Hybrid Integration in Micro-LED Display Manufacturing

An augmented LED array assembly for high-lumen lighting applications, such as automotive headlights, improves the integration of the LED array with electrical connections and heat dissipation. The LED array assembly includes a micro-LED array mounted on a driver IC bonded to contact pads on a flexible PCB. This eliminates wire bonding and allows accurate connection of the LED array to the PCB. The PCB can be flexed to accommodate different form factors. The PCB is attached to a heat spreader for thermal management.

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Hybrid integration in micro-LED with backplanes reduces cost and improves performance. The LED array is fabricated separately from the control circuitry. A thin-film circuit layer is deposited on the LED array to control the LEDs. The backplane with drive circuitry is then bonded to the circuit layer using a reduced number of metal bonds. This allows the LEDs to act as the support structure for the circuitry, reducing bump count. The thin-film circuits can be interconnected to further reduce bonds. The bonding uses low-temperature bumps to avoid mismatches.

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A method and device structure for fabricating high-performance microLED displays with improved pixel density, efficiency and integration compared to conventional approaches. The method involves hybrid bonding of the microLED array wafer to a CMOS driver circuit wafer without using through-silicon vias. The microLEDs are individually connected to CMOS circuitry using contacts on the bottom side of the microLED wafer and matching contacts on the CMOS wafer. This allows dense microLED arrays to be seamlessly integrated with CMOS circuits without sacrificing pixel fill factor or performance.

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A manufacturing method for LED-based display chips with improved electrical connections. The method involves forming trenches that cross through the LED stack and substrate to isolate the LED area. This allows separate electrical connections to the LED and circuit areas on the chip surface. The trenches are filled with insulating material except at the bottom where they expose the LED layer. This allows electrical access to the LED without shorting it through the control circuit. The method involves depositing metal layers on the substrate and LED stack, bonding the LED stack to the substrate, then forming the trenches.

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MicroLED display chips with reduced crosstalk and improved color conversion efficiency. The chips have a metal barrier between adjacent color conversion layers to prevent light leakage. This reduces crosstalk between pixels. The barrier also reflects light into the conversion layer for improved efficiency. The barrier is formed by patterning a metal layer over the light shielding structure. The barrier has a solid wall between the color conversion layers. This requires only one patterning step compared to separate barriers for each layer. The barrier also improves heat dissipation. The barrier shape and hole size can be adjusted to optimize light extraction and conversion efficiency.

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Improving the efficiency and light extraction of microLED displays, as well as enabling high-resolution microLED arrays with smaller pitches and easier electrical connections. The techniques involve: 1. Internal quantum efficiency improvement: Using a special epitaxial growth process to reduce surface recombination and improve internal quantum efficiency of microLEDs. The process involves doping the active region with magnesium and annealing it at high temperatures to activate the dopants. This passivates surface defects and reduces non-radiative recombination. 2. External quantum efficiency improvement: Modifying the microLED structure to extract more light. This includes optimizing the mesa shape, sidewall facets, and reflectors to minimize trapped light and maximize extraction efficiency. 3. Display panel design: Using stacked microLED structures to increase the packing density of the display. The microLEDs are vertically stacked

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Heterogeneous integrated full-color Micro-LED display panel with improved transfer and alignment method. The method involves growing blue-green dual-wavelength Micro-LED chips on one carrier and red Micro-LED chips on another carrier. Then, the carriers with the arrays of chips are aligned and bonded to a target substrate with electronics. This allows transferring and aligning a large number of Micro-LED chips in arrays without individual chip pick-and-place. The chips are bonded to the substrate through electrode holes filled with conductive material.

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MicroLED microdisplay chip with improved color efficiency and manufacturing simplicity for applications like AR/VR displays. The chip has separate red, green, and blue subpixels stacked without color overlap. This allows independent driving of each color. The subpixel layers are isolated by through-holes in the planarization layer, enabling independent reflective structures for each color. A barrier layer protects the reflective layer from contact resistance. The manufacturing method involves sequentially forming the subpixels without distinguishing order.

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Display panel design with improved stability and yield of microLED chips compared to existing panels. The panel has the microLED layer and thin film transistor (TFT) array on the backside of the base substrate instead of on the light-output side. This allows mass transferring the microLEDs first, then forming the TFTs directly on the backside. This eliminates the need for intermediate bonding steps when transferring the fragile microLEDs, improving their reliability and yield.

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LED display with improved resolution, heat dissipation, and isolation between pixels. The display has LED chips embedded in microholes in a metal layer instead of attaching them directly to the substrate. This allows the electrodes to be in the same plane for easier electrical connection and better resolution. The metal layer also provides thermal conductivity for better heat dissipation and isolation between pixels due to the embedded chips. The display is manufactured by forming the metal layer, etching microholes, embedding chips, and adding the driving layer.

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Transfer method for micro LED displays that improves accuracy and reduces damage compared to conventional methods. The method involves using a temporary substrate with layers for receiving and transferring micro LEDs. The receiving layer improves orderliness and the transfer layer enables selective transfer. After transferring micro LEDs to the temporary substrate, the receiving layer is patterned to remove spaces between LEDs. Then the transfer layer is processed to release specific LEDs. This allows selective transfer of LED arrays with custom spacing and arrangement.

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A method to improve the efficiency and yield of transferring micro LEDs from growth substrates to display substrates in order to fabricate micro LED displays. The method involves transferring micro LEDs of multiple colors from growth substrates to temporary substrates first. Then, micro LEDs of the same colors from the temporary substrates are simultaneously transferred to the display substrate. This reduces the number of transfers and improves yield compared to transferring individually from growth substrates. The temporary substrates have packed color arrangement for easier pickup and alignment.

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Micro LED array display device that enables individually driving and controlling micro LED pixels using flip chip bonding on a CMOS backplane. The display has a micro LED panel with multiple pixels, a CMOS backplane with cells corresponding to each pixel, and bumps between them. The micro LED pixels are flip chip bonded to the CMOS cells to drive them individually. This simplifies wiring and eliminates data lines compared to connecting each pixel. The display can also be a full color implementation with red, green, and blue micro LED panels bonded to the same CMOS backplane.

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Active full-color MicroLED display device with improved yield and manufacturing efficiency by integrating the MicroLED array and driver circuitry on a single silicon substrate instead of transferring pre-made MicroLEDs. The device has a silicon substrate with an epitaxial layer of LED material on one side. MicroLEDs are formed on the epitaxial layer by etching. A pixel driving circuit is prepared on the other side of the substrate. This avoids the complex and low yield microtransfer method of attaching pre-made MicroLEDs to a display backplane.

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MicroLED display chip with improved efficiency and display quality by covering the LED elements with conversion elements and reflective layers. The method involves forming microLED elements on one side of a driving panel. Wavelength conversion elements are placed on the same side, one for each microLED, covering the LED surface. Reflective layers are formed on the sides of the conversion elements. This reflects both the microLED's excitation light and the converted light. The reflective layers prevent light leakage and improve efficiency and collimation compared to uncovered conversion elements.

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A method for transferring micro LED arrays to displays without damaging the micro LEDs that don't need to be moved. The method involves selectively transferring only the micro LEDs that need to be moved while leaving the ones that should stay on the source substrate in place. This is done by using a console with adsorption zones for the static micro LEDs. During transfer, the micro LEDs that should be moved are picked up by the transfer head, but the ones on the console are not disturbed. This prevents accidental dislodging of the micro LEDs that are supposed to remain on the source substrate.

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Micro LED microdisplay device structure with low crosstalk and small size, achieved by flipping the micro LED array and bonding it to the driving circuit instead of directly attaching the LED wafer. This allows etching the LED substrate after bonding to separate the pixels. Black filling or a reflective layer between pixels absorbs/reflects light that would otherwise leak and cause crosstalk. The microdisplay structure has flip-chip bonded micro LED array, driving circuit, and separated pixels with reduced crosstalk compared to direct bonding.

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Micro LED display module with improved transfer precision, reduced defects, higher throughput, and better contrast. The module has a substrate with positioned recesses to match the micro LED chips. This avoids offset during transfer and improves yield. The recesses also prevent crosstalk between pixels. The module uses quantum dot materials for full color micro LEDs with better purity. It has a transparent black matrix to improve contrast. The micro LEDs are matched to the recesses with beveled edges to improve brightness. The display uses only blue micro LEDs for consistent brightness. The black matrix is applied first then transparent encapsulation avoids brightness loss.

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MicroLED display device and preparation method without integrated color conversion layers for full-color displays. The display has separate red, green, and blue MicroLED arrays directly emitting their colors instead of using a single monochrome MicroLED array with a wavelength conversion layer. The red and green MicroLED arrays are stacked on the driving substrate with escape holes allowing access to the underlying red MicroLEDs. This enables independent driving of each color without needing integrated color conversion.

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Micro LED display panel and manufacturing method that allows making a micro LED display without transferring the micro LED chips. The micro LED and transistor driving element are both formed on the same substrate plane. This reduces thickness and simplifies connections compared to transfer methods. The micro LED and transistor are electrically connected via wires through contact holes in the passivation layer. The micro LED and transistor are manufactured by sequential steps on the substrate including growing the LED stack, forming the transistor, and removing excess LED stack.

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