Evaluation of novel lactone derivatives for chemically amplified EUV resists

EUV lithography is the most favorable process for high volume manufacturing of semiconductor devices beyond 1X nm half-pitch at present. Many efforts have revealed effective proton sources 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 ter/tetrapolymers containing novel lactone derivatives - LCHO and LAATB - as model photopolymers and exposed the resist samples based on these polymers to EUV and EB radiation. On the basis of the lithographic performances of these photoresists, we evaluated the characteristics of lactone derivatives upon exposure to EUV radiation. We discuss the relationship between the chemical structures of these derivatives and lithographic performance.