Patent ID: 8822129

Claim:
A pattern forming method comprising: (1) forming a film by using an electron beam-sensitive or extreme ultraviolet-sensitive resin composition containing (A) a resin that contains a repeating unit having a partial structure represented by the following formula (A1) and can decrease the solubility for a developer containing an organic solvent by the action of an acid, and (B) a compound capable of generating an acid upon irradiation with an electron beam or an extreme ultraviolet ray, (2) exposing the film by using an electron beam or an extreme ultraviolet ray, and (4) developing the exposed film by using an organic solvent-containing developer to form a negative pattern: wherein each of R 1 , R 2 and R 3 independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, a halogen atom, a cyano group or an alkoxycarbonyl group, R 3 may combine with L 1 or Ar 1 to form a ring, and in this case, R 3 represents an alkylene group; L 1 represents a single bond; Ar 1 represents a (p+1)-valent aromatic ring group and in the case of combining with R 3 to form a ring, Ar 1 represents a (p+2)-valent aromatic ring group; Ra represents a hydrogen atom or a group capable of leaving by the action of an acid; and p represents an integer of 1 to 4, and when a plurality of Ra's are present, each Ra may be the same as or different from every other Ra; and further wherein the content of the repeating unit having a partial structure represented by formula (A1) is from 30 to 70 mol % based on all repeating units of the resin (A).