This paper presents an overview of the Moving-mask UV (ultraviolet) lithography technique and a photoresist profile simulation for the Moving-mask UV lithography using a positive-tone thick photoresist. In order to realize a wide variety of 3-D (three-dimensional) microstructures, the developed proximity 3-D UV lithography apparatus adopts the "moving-mask lithography" concept. Furthermore, we propose a practical photoresist profile simulation approach adopting the "Fast Marching Method" to consider the photoresist dissolution vector in the development process. The proposed approach deals with two important factors to control 3-D thick photoresist profile: the effect of UV light diffraction and non-uniform photoresist properties along thickness direction. Through moving-mask UV lithography experiments, (1) the capability of the moving-mask UV lithography for 3-D microstructuring, and (2) the validity of the proposed photoresist profile simulation, were successfully confirmed.
