Three-dimensional photolithography using built-in lens mask

Abstract

Three-dimensional lithography processes are required to fabricate the complex structures of advanced MEMS devices. The built-in lens mask has a complex transmittance amplitude and emulates the optical wave planes of arbitrarily shaped images that are to be focused on a focal plane. In our previous work, the authors proposed a novel three-dimensional imaging method using a multifocusing built-in lens mask in a computational simulation study. In this work, the authors study the three-dimensional photolithography process experimentally using this built-in lens mask. A pyramidal frame pattern is used to expose a negative thick resist layer (SU-8), and three-dimensional structures are successfully obtained using a single mask and a single-shot photolithography process. The experimental results agree fairly well with those from the computational simulations.