Evaluation of hydroxyl derivatives for chemically amplified extreme ultraviolet resist

Extreme ultraviolet (EUV) lithography is the most favorable process for high volume manufacturing of semiconductor devices at 22nm half-pitch and below. Many efforts have revealed that the phenolic hydroxyl groups of polymers are also an effective proton source in acid generation in EUV resists, and the effective proton generation and the control of the generated acid diffusion are required to improve the breakthrough of the resolution - line width roughness sensitivity (RLS) trade-off. To clarify the lithographic performance of these derivatives, we synthesized the acrylic terpolymers containing phenolic and alcoholic hydroxyl derivatives as model photopolymers and exposed the resist samples based on these polymers to EUV and electron beam (EB) radiation. On the basis of the lithographic performances of these resist samples, we evaluated the characteristics of phenolic and alcoholic derivatives upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.