To provide a positive resist composition capable of achieving excellent MEF and a resist pattern forming method.
The positive resist composition comprises a resin component A having acid-dissociable dissolution inhibiting groups and alkali solubility increased by the action of an acid and an acid generator component B which generates an acid upon exposure to light, wherein the resin component A comprises a resin A1 having a constitutional unit a1 derived from an acrylic ester having a linear tertiary alkyl ester type acid-dissociable dissolution inhibiting group and a resin A2 having a constitutional unit a1' derived from an acrylic ester having a circular tertiary alkyl ester type acid-dissociable dissolution inhibiting group and not having the constitutional unit a1, and the acid generator component B comprises an onium salt B1 having an anion represented by formula (I), wherein R4 represents a 3C alkyl group or a 3C fluoroalkyl group.
Masatake Shiga
Masakazu Aoyama
Suzuki Mitsuyoshi
Noriko Yanai