Patent ID: 6949329

Claim:
A pattern formation method comprising the steps of: forming a resist film with a thickness of 250 nm or less from a positive chemically amplified resist material including a base polymer, a first acid generator and a second acid generator that have at least one electron attractive group introduced into a meta position of an aromatic ring included in each of a counter anion and generator an acid through irradiation with energy beams; performing pattern exposure by selectively irradiating said resist film with electron beams or extreme UV of a wavelength of a 1 nm through 30 nm band; and developing said resist film after the pattern exposure, whereby forming a resist pattern; wherein said first acid generator includes a compound represented by general formula (1): where R 2 and R 4 are the same or different, at least one of which is not a hydrogen atom, and are selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group and a trifluoromethyl group; R 1 , R 3 and R 5 are the same or different and each is a hydrogen atom or a halogen atom; R 6 is a hydrogen atom or a linear or branched alkyl group having a carbon number of 1 through 4; and R 7 is a linear or branched alkyl group having a carbon number of 1 through 4; wherein said second acid generator includes a compound represented by general formula (2): wherein R 8 and R 10 are the same or different, at least one of which is not a hydrogen atom, and are selected from the group consisting of a hydrogen atom, a halogen atom, a nitro group and a trifluoromethyl group; and R 9 , R 11 and R 17 are the same or different and each is a hydrogen atom or a halogen atom, wherein the weight ratio of said compound represented by general formula (1) to said compound represented by general formula (2) is 0.2 through 2.0.