Chemically amplified positive photoresist composition and pattern forming method using same

A chemically amplified positive photoresist composition comprising (A) an alkali-soluble resin, (B) at least one plasticizer selected from a group consisting of an alkali-soluble vinyl resin and an acid-dissociable group containing vinyl resin, (C) a photo acid generator, (D) an organic solvent, and (E) a basic compound;

• wherein the alkali-soluble resin (A), comprises a polymer comprising recurring units represented by a general formula (1), a general formula (2) and a general formula (3) and has a weight average molecular weight of 1,000 to 200,000;
• wherein R1 is hydrogen, alkyl or halogen, R2 is hydrogen or alkyl, R3 is C4-C12 tertiary alkyl, m is a positive integer of 1 to 5;
• the amount of the plasticizer (B) in the composition is 2-10 parts by mass per 100 parts by mass of the alkali-soluble resin (A);
• the amount of the photoacid generator (C) in the composition is 1 to 10 parts by mass per 100 parts by mass of the alkali-soluble resin (A);
• the amount of the base (E) in the composition is 0.01-1 parts by mass per 100 parts by mass of the alkali-soluble resin (A);
• and
• the organic solvent (D) is selected from the group consisting of propylene glycol monomethylether arid propylene glycol dimethyl ether mixture, propylene glycol monomethylether and methylisobutylketone mixture, propylene glycol monomethylether and methylethylketone mixture, propylene glycol monomethylether arid n-butyl acetate mixture, propylene glycol monomethylether and cyclopentyl methyl ether mixture, and propylene glycol monomethylether and propyl propionate mixture.