Imaging characteristics of binary and phase shift masks for EUV projection lithography

Projection lithography at wavelengths in the extreme ultraviolet spectral range between 5 and 20 nm (EUV-lithography) employs reflective optical components including masks. This article applies rigorous electromagnetic field (EMF) simulation in combination with accurate projection image modeling to explore the impact of typical mask geometry parameters on the characteristics of lithographic processes. This includes telecentricity and shadowing effects resulting from the off-axis illumination in EUV systems and mask induced aberration-like effects. The importance of these effects for several alternative mask concepts including attenuated and alternating phase shift masks is investigated.