Attenuated PSM for EUV: Can they mitigate 3D mask effects?

Abstract

The understanding, characterization and mitigation of 3D mask effects including telecentricity errors, contrast fading and best focus shifts becomes increasingly important for the performance optimization of future extreme ultraviolet (EUV) projection systems and mask designs. The scattering of light at the absorber edges results in significant phase deformations, which impact the effective phase and the lithographic performance of attenuated phase shift mask (attPSM) for EUV. We employ rigorous mask and imaging simulations in combination with multi-objective optimization techniques to identify the most appropriate material properties, mask and source geometries and to explore the potential of attPSMs for future EUV imaging.