High aspect-ratio SU-8 resist nano-pillar lattice by e-beam direct writing and its application for liquid trapping

We report the fabrication of periodic lattices of high aspect-ratio nano-pillars made of SU-8 polymeric material by using direct electron-beam writing. Process parameters are optimized in order to control proximity effects and photoacid-generator diffusion determining feature resolution and material stiffness. We demonstrate nanostructured surfaces consisting of lattices of SU-8 nano-pillars with aspect-ratio as high as 3.8:1, improving previous reported results significantly. We also show the capability of these structures to trap liquid–water infiltrated among the SU-8 nano-pillars after proper chemical treatment.