Directional photofluidization mediated capillary force lithography

Abstract

furthermore, any structural modification from a mold pattern is quite challenging due to an difficulty in controlling the degree of fluidization by both heat and solvent. In this study, we introduce a new concept of capillary force lithography, termed directional photofluidization (DPF) CFL, which exploits the fluidization of polymer induced by simple far-field light exposure. The room temperature DPF-CFL process allows a pattern formulation in stable manner with avoiding any deformation issue of elastomeric mold. Furthermore, the degree of fluidization can be deterministically controlled by light, which provides unprecedented structural controllability in pattern height. As a proof-of-concept, azobenzene-containing material that shows directional photofluidic behavior is used as a pattern former, and various micro/nano structures in large area are successfully fabricated in fast manner by developing a light-irradiation protocol. The formation of multi-scale structure is also successfully demonstrated, ensuring its wide applicability to various applications.

Capillary force lithography (CFL) is an attractive lithography technique that can fabricate high-resolution pattern in large area and in simple manner. However, conventional CFL, where it uses heat or solvent to fluidize polymer, has issued that the applied heat or solvent incurs thermal expansion or deformation of elastomeric mold