Preparation of Ultra-Small 5 μm Blue InGaN Micro-Light-Emitting Diodes

With the increasing popularity of augmented and virtual reality systems, micro light-emitting diodes (μLEDs) have emerged as a key area of research. The preparation process for ultra-small-size μLEDs is still underdeveloping and hinders the industrialization of μLEDs microdisplay technology. Based on conventional contact ultraviolet lithography, a study was conducted on the fabrication process of ultra-small μLEDs. A 5 μm mesa structure was defined using a two-step photoresist -silicon dioxide etching scheme, and the formation process of small-sized mesas was investigated. The coating and stripping scheme for small-sized electrodes were optimized using a bilayer photoresist bonding process to achieve electrode expansion and preparation with small conductor widths. Arrays of 5 × 5 μm
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μLEDs with uniform surface morphology and good optoelectronic properties were then fabricated. This approach provides a practical solution for scaling up sub-10 μm μLEDs for display applications.