Micro-LED Quality Validation

Enabling testing, repair, and replacement of micro devices integrated into a system substrate like an emissive display. It provides methods and structures for identifying, fixing, and replacing defective micro devices in integrated systems like displays. The methods involve using temporary electrodes to bias and test floating contacts, optical sensors to measure light output, and fuses to disconnect defective devices. The structures include spare circuits, repair pads, and defect mapping blocks for populating and connecting replacements.

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Repairing techniques for micro LED displays to increase yield and reduce cost when defective micro LEDs are found after transfer to the system substrate. The techniques include replacing defective micro LEDs with spare ones, converting color of spares to match defects, mapping spare locations, and spatial coordinate variation to mitigate visual artifacts. It also involves calibration to correct for spatial non-uniformity induced by repair techniques.

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Transferring microdevices like LEDs from a donor substrate to a receiver substrate in a way that avoids defects and performance issues. The technique involves arranging the microdevices in cartridges, aligning the cartridges with a template, bonding them, then transferring the devices from the template to the receiver substrate. This allows selective transfer of defect-free devices from cartridges rather than transferring entire blocks from the donor substrate. The cartridges can also have anchors to hold the devices during transfer and vias for temperature and mechanical property adjustment. By testing the cartridges and adjusting transfers based on defect data, it reduces defects in the final receiver substrate.

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Micro-LEDs are suitable as special light sources that serve small sensors and for optical communication. The most important technology these applications is Micro-LED high-precision transfer (0.5 m positional accuracy). existing has the problem of low position accuracy. This study proposes a high-position-precision method based on vibrations. A single system microgripper was designed to achieve positioning. Compared with other methods, this can be used in conjunction microscope camera Micro-LED. To test performance our proposed method, Micro-LED, length approximately 40, width 20, thickness 4 m, transferred. tested. Subsequently, 5 6 array results show 2 out 30 have deviation exceeding 3 so failure. success rate >90%. root-mean-square error 0.8 m. experimental exhibits good transfers.

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Abstract MicroLED is considered as the new generation of display with longlifetime, high contrast and brightness, splicing capability, so forth. Mass transfer bottleneck that limits manufacturing at large volume, due to factors such laserlift off, pickup, metal bonding. Metal bonding between chip substrate one most important lightup yield. To solve key thermal mismatch issue backplane donor during heating, laserassisted process could be a viable solution. We present study in metallic element Au/Sn productivity, capability low cost, well good electrical conductivity, excellent strength, sensitivity surface roughness. The result presented 62 78 pixels fullcolor display, reliable connection microscale LED devices can achieved under 250C without any damage backplane. In conclusion, micromorphology formation mechanism different alloy phase compositions welded elements have been thoroughly studied, feasible technological methodology has developed for upcoming mass production modules.

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MicroLED display technology with improved yield and production efficiency by selectively removing defective microLEDs before transfer to the final substrate. The method involves testing the microLEDs on a temporary substrate, removing any failures, and then transferring the remaining good microLEDs to the permanent display substrate. This prevents filling gaps with extra microLEDs, which can have lower yield. The key is controlling the transfer and removal rates so more defective microLEDs are removed than replaced.

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Micro light-emitting diode (Micro-LED) is widely regarded as a highly promising technology in the current display field due to its excellent performance, but core issue hindering further development of Micro-LED how achieve high-precision and high-yield transfer. In this study, laser-induced forward transfer (LIFT) adopted main technique, novel blister-type dynamic release layer (DRL) material selected, characterized by gentle process minimal residue on chip after Chip-on-wafer (COW) structure that fabricates large number Micro-LEDs (15 30 m2) sapphire substrate. The COW-on-head (COH) bonding method can control uniformity overall height before within 3.5%, which favorable for subsequent stable Based analysis close relationship between gap laser energy density, study successfully achieved red/green/blue (R/G/B) chips (6400, respectively) onto corresponding chip-on-carrier 2 (COC-2), all them have one-step yield over 99.3% an average offset m or less. It worth mentioning mentioned paper different from testing repairing chips. fully reflect quality. order verify validity 1 in., f... Read More

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Abstract Microlight emitting diode (LED) based LED on silicon (LEDoS) is a promising candidate for nextgeneration AR and VR displays due to superior pixel performance potential high resolution. Traditional RGB pixels are placed single plane, which limits the To overcome this, vertically stacked using heterogeneous monolithic 3D integration (M3D) have been explored. However, previously reported vertical LED not considered heat dissipation capability of pixels, indeed important in future micro displays, utilized materials incompatible with standard CMOS processes, further limiting their practicality LEDoS. The critical regions constraint, bonding medium, typically organic polymer materials. Therefore, handle issue, fullcolor LEDs demonstrated oxide (SiO 2 ) yttrium (Y O 3 ), as mediums. These CMOScompatible offer thermal conductivity at least 10 times higher than conventional polymers. InGaN/GaN blue bonded oxides show improved management, leading external quantum efficiency (EQE) better color characteristics, including narrower full width half maximum (FWHM) purity. ... Read More

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A defect inspection system that uses machine learning to improve defect detection in products. The system has a learning unit that trains a model to estimate multiple non-defective versions of an image. When inspecting a product, the system captures an image, inputs it into the trained model, and receives multiple estimated non-defective versions. By comparing the actual and estimated non-defective images, the system can more accurately identify and isolate defects.

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Inspection apparatus for defect detection in high-resolution display devices like micro-OLEDs without using sensor defect data. The method involves capturing an image of the display with sensor pixels, locating defect candidate positions, generating contours around the candidates, and determining if they are actual defects based on contour perimeter. This allows detection without sensor defect data, mitigating issues with sensor noise and pixel defects appearing as false positives.

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Testing large arrays of devices like microLED displays using parallel excitation with repeated contact and interaction without damaging the probes or devices. The test tool has multiple probes that can simultaneously contact multiple device contacts. Liquid metal is applied to the probe tips before contact to act as a flexible interface. When the probes touch the device contacts, oxide pinholes form in the contact layer allowing electrical connection through the liquid metal bridge. This allows repeated contact without damaging the probes or devices. The liquid metal seals when the probes lift, preventing flow onto the contacts. This enables parallel device excitation with optical monitoring without active feedback loops to maintain probe-contact alignment.

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A test system for efficiently and accurately measuring the performance of small form factor LEDs like micro-LEDs and nano-LEDs. The system uses a probe head with obliquely angled probes that can contact the tiny LEDs without blocking emitted light. It also has a movable cover over the probe slot to protect the probes when not in use. The probes measure voltage and current through the LEDs while a separate light detector captures emitted light. This allows calculating the quantum efficiency based on all three parameters.

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Determining quality of inspection data using a machine learning model that can distinguish between defective and non-defective products without requiring labeled training data for defective products. The method involves generating training data from non-defective products, learning the ML model on that, preparing a feature spectrum from a specific layer output for non-defective training data, and using that learned model and feature spectrum to determine quality of unseen inspection data. Similarity between the inspection data feature spectrum and the known feature spectrum is calculated and a threshold is used to determine if it's non-defective or defective.

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Contactless probe for measuring cycles of microdevices like LEDs without needing post-processing steps. The probe has an electrode covering a dielectric to stimulate the microdevice capacitively. A switch keeps the device on after an active portion of the stimulus signal. This allows measuring cycles without contact, resets, or parasitic effects. The stimulus amplitude can also be increased after each cycle.

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Detecting defects in display panels using deep learning to accurately locate and identify the type of defect in a stacked structure of a display panel. The method involves collecting images of defects and layers from a database, learning the defect and layer information using a deep learning model, and then using that model to extract the location of the defect in the stacked structure. The deep learning allows detecting detailed defect locations and layer associations compared to just checking for defects in a single image.

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Method to monitor the growth quality of nitride semiconductor films like GaN using a template substrate with a mask during molecular beam epitaxy (MBE) growth. The technique involves growing the nitride semiconductor on a template substrate with a mask pattern. By using light with a wavelength absorbed by the nitride semiconductor at the growth temperature, fringes are observed in the reflected light due to interference between the mask and the growing nitride film. This allows real-time monitoring of the nitride film growth without requiring a flat substrate.

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Display device with improved reliability by adding inspection lines that overlap the cathode-power electrode connection regions to check for defects. The inspection lines are disposed on the encapsulation layer covering the display pixels. They overlap the cathode-power connections and allow capacitance measurements to determine if the connections are stable. If the measured capacitance is within a range, it indicates good connection. If outside the range, it indicates defective connection. This provides a reliability check for the cathode-power connections to prevent issues like noise leakage through poorly connected cathodes.

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Determining epitaxial defects in semiconductor substrates using frequency domain filtering and machine learning to improve yield and manufacturing efficiency. The method involves applying a frequency domain filter to substrate images to enhance defect visibility. Then feature detection is performed on the filtered images to count epitaxial defects. This allows automated, scalable defect classification and counting compared to manual review of raw images. The defect count can trigger corrective actions to address the underlying issues.

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Pixel circuit for display devices that allows simultaneous driving and sensing of electrical characteristics of multiple driving transistors for a pixel to improve reliability, efficiency, and HDR contrast. The circuit has two driving transistors connected to the pixel's light-emitting element and a sensing part to simultaneously drive one transistor while sensing the electrical characteristics of the other transistor. This allows real-time monitoring of transistor performance while simultaneously emitting light. It enables selection of the best performing transistor for driving the light-emitting element and detects deterioration early. The simultaneous emission of light from both transistors increases luminance with less current and improves display performance.

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A non-destructive method to analyze and monitor defects in semiconductor structures using femtosecond laser beams and terahertz waves. The method involves injecting femtosecond lasers into the semiconductor to create electron excitations, then irradiating terahertz waves onto the semiconductor while the excitations recombine. The terahertz wave transmittance/reflectance is measured and analyzed to determine defect densities and distributions in the semiconductor. The analysis involves tracking the recombination time constants of the excited carriers. This allows non-contact, non-destructive analysis of defects in complex 3D semiconductor structures.

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