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EUV chemically amplified resists (CARs) have had big problems about pattern defects due to stochastic effects from photon shot noise and acid diffusion blur less than 13 nm HP. There is a trade-off relationship between resolution, line width roughness (LWR), and sensitivity (RLS trade-off). Moreover, etching durability of CARs have also been gradually surfaced as an issue due to reducing film thickness to prevent pattern collapse. In the circumstances, some of the new resist platform have been investigated. Above all, metal oxide resist and dry resist were particularly achieved good patterning performance and etching durability as negative type resist by using metal component in the systems. However, EUV lithography mainly need positive tone resist for logic device patterning. From these viewpoints, we aimed to make an organometal positive tone EUV chemically amplified resist concept based on our negative type metal resist. Previously, we proposed a novel chemically amplified resist platform that consists of polarity changer, organotin compound and others. Polymers having triarylsulfonium cations, organotin compound and diarylmethanol as side chains were designed to realize a negative imaging property. Upon exposure to EUV or electron beam (EB), the ionic component is transferred to nonionic component through the decomposition of polymer-bounded onium cation (PBC). The polymer molecules are also crosslinked through the acid catalytic etherification. We demonstrated a high sensitivity and low LER property by using acetonitrile aqueous solution developer. This resist obtains a dissolution contrast to polar solvent by changing to hydrophobic structure though the decomposition of the onium cation and crosslinking. Presumably, this resist can convert from negative to positive tone by changing the part of reaction for making dissolution contrast from cross-link to chain scission and developer from polar solvent to nonpolar solvent for exposed material dissolution. After some modification of the resist material, we demonstrate positive tone imaging by using alkyl acetate as a developer.
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