Effect of Acid Diffusion and Polymer Structure on Line Edge Roughness

概要

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As the dimensions of resist patterns have been reduced, nanoscale resist topographies such as line edge roughness (LER) or line width roughness (LWR) have become a priority issue in lithographic processes. Despite many studies, the details of LER formation mechanism are still unclear. In this work, the effect of protecting groups on LER was investigated using polarity-change-type chemically amplified resists with the backbone polymer of poly(4-hydroxystyrene). LERs in the short acid diffusion range correspond to the fluctuation of initial acid distribution. LER decreases with line width expansion and reaches the minimum at a certain length, which depends on exposure dose. However, the dependence of polymer structure on LER was not observed. Because a difference in protecting groups leads to a difference in acid diffusion constant, the difference had an effect on LER formation. However, when compared at the same diffusion length, the effect of polymer structure on LER is small at LERs examined in this work (3–4 nm).
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-09-30