Wavelength dependence of the resist sidewall angle in extreme ultraviolet lithography

We report experimental and theoretical studies of the resist sidewall angles produced using extreme ultraviolet lithography at exposure wavelengths of 37.5, 13.9, and 6.8 nm. We show that high resist absorption in this wavelength region leads to a significant degradation in pattern sidewall angle. Because steep resist profiles are needed in semiconductor manufacturing to ensure adequate linewidth control it seems unlikely that a single-layer resist process can be used in extreme ultraviolet lithography except at the shortest wavelength.