High‐Accuracy and Ultrahigh‐Density Electrofluidic Integration of Miniaturized LEDs for AR/VR Displays

ABSTRACT

Ultrahigh‐density integration of inorganic miniaturized light‐emitting diodes (LEDs) on silicon with sub‐micrometer placement accuracy is essential for next‐generation display applications, including augmented reality (AR) and virtual reality (VR) microdisplays. This work demonstrates a high‐accuracy bottom‐up electrofluidic assembly approach for indium gallium nitride (InGaN)‐based blue nano‐LEDs (nLEDs), achieving an exceptional assembly yield of 99.74% at pixel densities exceeding 5000 pixels per inch (PPI). The spatially resolved dielectrophoretic force generated by recessed microwells plays a critical role in ensuring high‐yield and high‐accuracy placement. In addition, electrostatic interactions between high‐aspect‐ratio nLEDs and biased electrodes further minimize alignment offsets to 0.06 ± 0.05 µm, approaching the precision of photolithographic processes. Using this method, we fabricated an nLED‐based blue microdisplay with a pixel resolution of 2936 PPI, where the assembled devices were electrically connected by post‐assembly metallization to enable electroluminescent operation. This bottom‐up integration, combined with conformal metallization, enables seamless hybridization of nLED pixels with Si complementary metal‐oxide semiconductor (CMOS) electronics without compromising pixel performance or increasing the process complexity. The demonstrated strategy provides a scalable and cost‐effective pathway for mass production of high‐resolution microdisplays.