US Patent 7175960 Positive resist composition and patterning process

A positive resist composition comprising a mixture of an alkali-soluble novolak resin prepared using m-cresol, p-cresol and 2,5-xylenol as starting reactants and a phenolic compound, wherein the hydrogen atoms of all hydroxyl groups are substituted in a proportion of 0.03–0.05 mol per hydrogen atom with 1,2-naphthoquinonediazidosulfonyl ester groups, has uniformity, high sensitivity and high resolution, and is improved in heat resistance, film retention, substrate adhesion, and storage stability.