Mask roughness impact on extreme UV and 193Â nm immersion lithography

► The optical system acts as a low pass filter for mask LER frequencies above a maximum cut off. ► The impact of illumination symmetry is assessed by applying two different illuminations on ArF. ► For vertical lines, dipole illuminations attenuates the roughness transfer but aerial image degrades. ► EUV exposures confirm the results and are compared with a similar study on a different platform.