Tiltable UV-LED Lithography for 3D Microfabrication

This paper presents a tiltable UV-LED lithography system for 3D microfabrication. Collimated light with adjustable intensity from 7-by-7 405-nm UV-LEDs was used as a light source. An orbital rotation of the UV-LED array provided the uniform light intensity. The key advantages of the proposed system create 3D light traces without the sample's tilt-rotational movement, which is used to cause non-uniform light exposure and sample instability. Also, the tiltable UV-LED lithography can directly pattern on a liquid photosensitive state resin that provides a rapid process without soft baking and post-exposure baking. Several 3D microstructures in hundreds-microns to millimeter heights were successfully fabricated including vertical pillars, inclined pillars, triangular slabs, single and dual microneedle, and multi-angled petals. The tiltable UV-LED lithography has a great potential for a 3D micromanufacturing area with various 3D MEMS applications.