Patent ID: 7851140

Claim:
A pattern forming method, comprising: forming a resist film by applying a resist composition for negative tone development, which contains (A) a resin capable of increasing a polarity of the resin (A) by an action of an acid to increase a solubility of the resin (A) in a positive tone developer which is an alkali developer and decrease a solubility of the resin (A) in a negative tone developer containing an organic solvent, (B) a compound capable of generating an acid having an acid dissociation index pKa of −4.0 or less upon irradiation with an actinic ray or radiation, and (C) a solvent; exposing the resist film; and developing the resist film after the exposing by using the negative tone developer, wherein the compound (B) is a compound capable of generating an acid represented by the following formula (P-1) upon irradiation with an actinic ray or radiation: in formula (P-1), each of Rc 1 and Rc 2 independently represents an organic group, and Rc 1 and Rc 2 may combine with each other to form a ring.