US Patent 7687222 Polymerizable ester compounds, polymers, resist compositions and patterning process

Novel polymerizable ester compounds having formulae (1) to (4) undergo no acid-induced decomposition by β-elimination wherein A1 is a polymerizable functional group having a carbon-carbon double bond, R1 is H or —C—(R5)3, R2 and R3 are alkyl, R4 is H or alkyl, R5 is a monovalent hydrocarbon group, X is alkylene, Y is methylene, ethylene or isopropylidene, Z is alkylene, and n=1 or 2. Resist compositions comprising polymers derived from the ester compounds have excellent sensitivity and resolution and lend themselves to micropatterning lithography.