Nano-stereolithography process for precise and effective 2D and 3D nano/microfabrication

Abstract

Since it has emerged as a new technology, two-photon polymerization (TPP) initiated through the non-linear process of a two-photon absorption in a photosensitizer has been studied intensively in two- and three-dimensional (2D and 3D) microfabrications for various polymeric applications. For the fabrication of 2D nano-patterns, a nano-replication printing (nRP) process has been developed using a voxel matrix scanning method. In this method, a two-tone (black and white) bitmap figure is used as the designed pattern shape and is transformed into a voxel matrix in order to control the on/off of a focused laser beam. Complicated 3D microstructures can also be fabricated using layer-by-layer accumulation of the sliced multiple contour scanning data derived from the 3D CAD data. After the polymerization process, the unsolidified liquid-state resin is removed by pouring solvents, such as ethanol, onto the resin, and then the polymerized microstructures are developed. In previous works, 3D micro-optical components, micromechanical devices, and photonic crystals have been fabricated successfully with a high spatial resolution of approximately 100 nm. Recent efforts have also improved the efficiency and precision of TPP. This paper presents the microfabrication techniques based on TPP recently developed in our Department.