Origin of frequency-dependent line edge roughness: Monte Carlo and fast Fourier-transform studies

The low-frequency line edge roughness (LER) of a chemically amplified resist (CAR) has a marked effect on the quality of electrical circuits, especially those produced by sub-30-nm-scale fabrication by extreme ultraviolet lithography. We examined the origin of frequency-dependent LER by Monte Carlo and dissolution simulations of a positive-tone CAR subjected to electron beam lithography. The correlation between frequency components and LER is highlighted to clarify which component is dominant. We found that the resist process parameters, such as the exposure dose, the base quencher, and the development, cause low-frequency LER even in the absence of mesoscale resist roughness.