Positive resist composition for immersion exposure and pattern forming method

A positive resist composition for immersion exposure, comprising the following (A) to (D):

• (A) a resin capable of decomposing by an action of an acid to increase a solubility of the resin in an alkali developer;
• (B) a compound capable of generating an acid upon irradiation with an actinic ray or radiation;
• (C) a resin having at least either one of a fluorine atom and a silicon atom;
• and
• (D) a mixed solvent containing at least one kind of a solvent selected from the group consisting of solvents represented by any one of the following formulae (S1) to (S3), in which a total amount of the at least one kind of the solvent is from 3 to 20 mass % based on all solvents of the mixed solvent (D):
• wherein each of R1 to R7 independently represents an alkyl group, a cycloalkyl group or an aryl group;
• and
• R1 and R2, R3 and R4, and R6 and R7 may combine with each other to form a ring, respectively;
• wherein the resin (C) contains at least one group selected from the following (x) to (z):
• (x) an alkali-soluble group;
• (y) a group capable of decomposing by the action of an alkali developer to increase the solubility in an alkali developer, and
• (z) a group capable of decomposing by the action of an acid;
• and
• the mixed solvent (D) is a mixed solvent containing only propylene glycol monomethyl ether acetate (PGMEA) and propylene carbonate.