Evaluation of alcoholic hydroxyl derivatives for chemically amplified extreme ultraviolet resist

摘要

Extreme ultraviolet (EUV) lithography is the most favorable process as next-generation lithography. For the development of EUV resists, phenolic materials such as poly (4-hydroxystyrene) have been investigated. Phenolic hydroxyl groups of polymers play an important role in acid diffusion, dissolution kinetics, and adhesion to substrates. Besides these important roles, phenolic hydroxyl groups are also an effective proton source in acid generation in EUV resists. However, the roles of alcohol hydroxyl groups have not been well-studied. To clarify the difference between phenolic and alcoholic hydroxyl groups upon exposure to EUV radiation, we synthesized acrylic terpolymers containing alcoholic hydroxyl groups as model photopolymers and exposed the resist samples based on these polymers to EUV radiation. On the basis of the lithographic performances of these resist samples, we evaluated the characteristics of alcoholic hydroxyl groups upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.