Process Simulation of Moving Mask Deep X-Ray Lithography

This paper presents a newly developed 3-Dimensional (3D) simulation system for Moving Mask Deep X-ray Lithography (MDXL) process, and its validation. The simulation system named X-ray Lithography Simulation System for 3-Dimensional Fabrication (X3D) is tailored to simulate a fabrication process of 3D microstructures by MDXL. X3D consists of three modules: mask generation, exposure and development. The exposure module calculates a dose distribution in resist using a generated X-ray mask pattern and its movement trajectory. The dose is then converted to a resist dissolution rate. The development module adopted the “Fast Marching Method” technique to calculate the 3D dissolution process and resultant 3D microstructures. This technique takes into account resist dissolution direction that is necessary for accurate 3D X-ray lithography simulation. The comparison between simulation results and measurements of “stairs-like” dose deposition pattern by MDXL showed that X3D correctly predicts the 3D dissolution process of exposed PMMA. Graduate School of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan Physical Electronics Laboratory, ETH Zurich, Hoenggerberg HPT-H4.2, Wolfgang-Pauli-Strasse 16, 8093 Zurich, Switzerland Graduate School of Science and Engineering, Ritsumeikan University, Noji-Higashi, Kusatsu, Shiga 525-8577, Japan IMTEK-Institute of Microsystem Technology, University of Freiburg, Georges-Koehler-Allee 102, D-79110 Freiburg, Germany