Ester compounds, polymers, resist compositions and patterning process

摘要

An ester compound of the following formula (1) is provided. <CHEM> R<1> is H, methyl or CH2CO2R<3>, R<2> is H, methyl or CO2R<3>, R<3> is C1-C15 alkyl, R<4> is branched or cyclic, tertiary C5-C20 alkyl group, Z is a divalent C1-C10 hydrocarbon group, and k is 0 or 1. A resist composition comprising as the base resin a polymer resulting from the ester compound is sensitive to high-energy radiation, has excellent sensitivity, resolution, and etching resistance, and is suited for micropatterning using electron beams or deep-UV.