Ester compounds and their preparation, polymers, resist compositions and patterning process

摘要

Novel ester compounds having formulae (1) to (4) wherein A¹ is a polymerizable functional group having a carbon-carbon double bond, A² is oxygen, methylene or ethylene, R¹ is a monovalent hydrocarbon group, R² is H or a monovalent hydrocarbon group, any pair of R¹ and/or R² may form an aliphatic hydrocarbon ring, R³ is a monovalent hydrocarbon group, and n is 0 to 6 are polymerizable into polymers. Resist compositions comprising the polymers as a base resin are thermally stable and sensitive to high-energy radiation, have excellent sensitivity and resolution, and lend themselves to micropatterning with electron beam or deep-UV.