Performance enhancement in micro-LED maskless lithography via in-situ two-photon-polymerized micro-lens arrays

Micro-LED arrays are promising digitally addressable light sources for maskless lithography owing to their compact size, electrical addressability, and pixel-level programmability. However, their broad emission angle can limit the coupling efficiency into the projection objective and reduce optical utilization. We demonstrate a visible-light micro-LED array-based maskless lithography system with a micro-lens array directly integrated onto the micro-LED array using two-photon polymerization. The micro-lens array narrows the main angular distribution to approximately ±30° and increases the projected radiant flux to 5.12 μW, corresponding to a 12.5% enhancement. By redistributing the emitted light into the inter-pixel regions, the micro-lens array suppresses the pixelated exposure texture and improves pattern continuity. Lithographic patterns with a minimum linewidth of 2.8 μm were achieved with the micro-lens-integrated device.