Relationship between Line Edge Roughness and Fluctuation of Acid Concentration in Chemically Amplified Resist

概要

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Line edge roughness (LER) is a critical issue in the development of chemically amplified resists used for extreme ultraviolet (EUV) lithography. The main cause of LER in state-of-the-art resists is the chemical inhomogeneity intrinsic to chemical reactions. However, the fluctuation of the initial acid concentration possibly caused by the inhomogeneous distribution of resist components such as acid generators becomes a concern with the reduction of feature sizes. In this study, the effect of the fluctuation of the initial acid concentration on LER was theoretically investigated on the basis of the reaction mechanisms of chemically amplified EUV resists. The fluctuation of line edge originating from the fluctuation of the initial acid concentration was compared with LER originating from the fluctuation of chemical reactions. Even at 16 nm half pitch, the fluctuation in the initial distribution was significantly reduced through catalytic chain reaction. The smoothing effect of acid diffusion is essential to meet the requirement for fine patterning with high sensitivity.
2010-09-25