US Patent 7611820 Positive resist composition and pattern-forming method using the same

A positive resist composition comprises:(A) a resin capable of increasing its solubility in an alkali developer by action of an acid and not containing a silicon atom;(B) a compound capable of generating an acid upon irradiation with actinic ray or radiation,(C) a silicon atom-containing resin having at least one group selected from groups (X) to (Z),(X) an alkali-soluble group,(Y) a group capable of decomposing by action of an alkali developer to increase the solubility of resin (C) in an alkali developer,(Z) a group capable of decomposing by action of an acid to increase the solubility of resin (C) in an alkali developer; and(D) a solvent.