Improvement of Spatial Resolution in Two-Photon Stereolithography

Two-photon stereolithography based on photopolymerization provides the ability to fabricate real three- dimensional (3D) microstructures beyond the resolution of focal size. In this paper, our recent research focusing on improvement of spatial resolution in two-photon stereolithography is reviewed. The influence of system and fabrication conditions in relation to the spatial resolution is discussed. For small and low aspect ratio voxels, a minimum power and minimum exposure time (MPMT) scheme is introduced. During the two-photon process, an ascending technique, wherein the truncation amount of volumetric pixels is controlled, can be applied to improve the resolution of two-dimensional patterns. 3D microfabrication with less than 100 nm resolution can be realized by using the radical quenching effect. After the two-photon process, the resolution of fabricated patterns can be refined to 60 nm by post-processing of plasma ashing.