US Patent 7189493 Polymer, positive resist composition, and patterning process using the same

There is disclosed a polymer which at least has the repeating unit represented by the following general formula (1a), and the repeating unit represented by the following general formula (1b) and/or the repeating unit represented by the following general formula (1c), and a positive resist composition comprising the polymer as a base resin. There can be provided a positive resist composition having high sensitivity and high resolution on exposure to a high energy beam, wherein line edge roughness is reduced since swelling at the time of development is suppressed, and the residue after development is little