Development of Programmable UV-LED Microlithography System for 3D Microfabrication

An advanced UV-LED microlithography system has been introduced for 3D microfabrication. The system comprises an array of UV-LEDs as a programmable light source, a tilt-rotational mask aligner frames to create 3D light traces, and a control computer unit for fully automated operation. A tilt-rotational substrate holder is equipped with high-precision servo motors to create multidirectional UV lights and thereafter fabricating 3D microstructures. The C++-based control software in the main computer provides unique optimal light exposure schemes such as dimming, selective lighting, and synchronizing the stage with the light source that can create complex 3D microstructures. The feature of an adjustable high light intensity up to 472 mW/cm² which used to be more than twice to the conventional systems, has enabled the accessible SU-8 photoresist thickness to a few millimeters. High aspect ratio 2000- $\mu \text{m}$ tall SU-8 pillars and various 3D microstructures including twisted ‘S’ structures, tapered hollow horn structures, open bow-tie structures, and vertical ‘V’ structures have been successfully fabricated to show the great potential the 3D devices in Bio and RF fields. [2021-0153]