Positive resist composition and method of forming resist pattern

A positive resist composition comprising:

• a base component (A) which exhibits increased solubility in an alkali developing solution under action of acid,
• an acid-generator component (B) which generates acid upon exposure, and
• a fluorine-containing polymeric compound (C′) which generates acid upon exposure,
• the base component (A) comprising a structural unit (a0-1) represented by general formula (a0-1) shown below and a structural unit (a1) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, and
• the fluorine-containing polymeric compound (C′) comprising a structural unit (c0) which generates acid upon exposure and a structural unit (c1 including at least one structural unit selected from the group consisting of structural units represented by general (c11-1-1) to (c11-1-4), (c11-2-1) to (c11-2-4) and (c12-1-2) to (c12-1-8) shown below:
• wherein each of R1 and R independently represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl group of 1 to 5 carbon atoms;
• R2 represents a divalent linking group;
• R3 represents a cyclic group containing —SO2— within the ring skeleton thereof;
• each of R51 and R52 independently represents a hydrogen atom, a halogen atom, an alkyl group of 1 to 5 carbon atoms or a halogenated alkyl groups of 1 to 5 carbon atoms, wherein the plurality of R51 or R52 may be the same or different from each other;
• each of a1, a2, a5, a7, a9 and a11 to a13 independently represents an integer of 1 to 5;
• a3 represents an integer of 1 to 3;
• each of a4, a6, a8 and a10 independently represents 0 or an integer of 1 to 5;
• each of b1 to b5 independently represents 0 or 1;
• R5′ represents a substituent;
• e represents an integer of 0 to 2;
• and each R21 independently represents a base dissociable group having a fluorine atom.