Moving mask UV lithography for three-dimensional structuring

This paper presents a systematic study on a novel 3D (three-dimensional) UV (ultraviolet) lithography apparatus for thick photoresist and a UV lithography process simulation for 3D microstructuring. In order to realize a wide variety of 3D microstructures, the developed proximity 3D UV lithography apparatus adopts the 'moving mask lithography' concept which was originally proposed by the authors for deep x-ray lithography. Furthermore, the authors propose a new practical photoresist profile simulation approach adopting the 'fast marching method' to consider the photoresist dissolution vector in the development process. A series of moving mask UV lithography experiments using a positive-tone photoresist (50 mu m thickness) successfully confirmed (1) the capability of the moving mask UV exposure technique for 3D microstructuring and (2) the validity of the proposed photoresist profile simulation.