Copolymer and composition for semiconductor lithography and process for producing the copolymer

A copolymer for semiconductor lithography according to [1], wherein the acid-labile, dissolution-suppressing group of the repeating unit (A) is selected from a structure represented by the following formula (L1)

• {in the formula (L1), ∘ is a bonding site of the acid-labile, dissolution-suppressing group, R13 and R14 are each independently a hydrocarbon group having 1 to 4 carbon atoms, R15 is a hydrocarbon group having 1 to 12 carbon atoms, and R15 may bond with R13 or R14 to form a ring}, or, a structure represented by the following formula (L2)
• {in the formula (L2), ∘ is a bonding site of the acid-labile, dissolution-suppressing group, R16 and R17 are each independently a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, R18 is a hydrocarbon group having 1 to 12 carbon atoms, and R16 may bond with R17 or R18 to form a ring}.

A copolymer for semiconductor lithography according to [2], wherein the repeating unit (A) has a structure represented by the following formula (A)

• {in the formula (A), R10 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, which may be substituted with fluorine atom, R11 is an alicyclic hydrocarbon group having 6 to 12 carbon atoms, which may contain oxygen atom or sulfur atom, n is an integer of 0 or 1, and R12 is an acid-labile, dissolution-suppressing group represented by the formula (L1) or (L2)}.

A copolymer for semiconductor lithography according to any of [1] to [3], wherein the repeating unit (B) has a structure represented by the following formula (B)

• [in the formula (B), R20 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, which may be substituted with fluorine atom, R21 is a single bond or an alicyclic hydrocarbon group having 5 to 12 carbon atoms, which may contain oxygen atom or sulfur atom, L3 has a lactone structure represented by the following formula (L3)
• {in the formula (L3), either one of R22 to R29 is a single bond having a bonding site as R21, and the remainder of R22 to R29 is a hydrogen atom, or, a hydrocarbon or alkoxy group having 1 to 4 carbon atoms, or,
• either one of R22 to R29 is a hydrocarbon group having 3 to 12 carbon atoms having a bonding site as R21 and bonds with either one or two of the remainder of R22 to R29 to form an alicyclic ring having 5 to 15 carbon atoms and which may contain oxygen atom or sulfur atom, and the remainder of R22 to R29 is such that either one or two of the remainder is a single bond for forming the above-mentioned alicyclic ring having 5 to 15 carbon atoms and the rest of the remainder is a hydrogen atom, or, a hydrocarbon or alkoxy group having 1 to 4 carbon atoms, and m is an integer of 0 or 1}, and L3 is bonded with R21 in one or two single bonds].

A copolymer for semiconductor lithography according to any of [1] to [4], wherein the repeating unit (C) has a structure represented by the following formula (C)

• {in the formula (C), R33 is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, which may be substituted with fluorine atom, R34 to R36 are each independently a hydrogen atom or a hydroxyl group, and at least one of R34 to R36 is a hydroxyl group}.

A composition for semiconductor lithography, characterized by comprising at least a copolymer according any of [1] to [5], a radiation-sensitive acid generator and an organic solvent.

A composition for semiconductor lithography according to [6], which is used in dry lithography.

A composition for semiconductor lithography according to [6], which is used in immersion lithography.

A process for producing a copolymer for semiconductor lithography, having at least (A) a repeating unit having a structure which has an alkali-soluble group protected by an acid-labile, dissolution-suppressing group, (B) a repeating group having a lactone structure and (C) a repeating group having an alcoholic hydroxyl group, which process being characterized by dissolving, in an organic solvent, at least one monomer selected from a monomer giving the repeating unit (A), a monomer giving the repeating unit (B) and a monomer giving the repeating unit (C), contacting the resulting solution with water followed by giving rise to phase separation, and, thereafter, copolymerizing the monomers.

A process for producing a copolymer for semiconductor lithography, having at least (A) a repeating unit having a structure which has an alkali-soluble group protected by an acid-dissociable dissolution-suppressing group, (B) a repeating group having a lactone structure and (C) a repeating group having an alcoholic hydroxyl group, which process being characterized by dissolving, in an organic solvent, at least one monomer selected from a monomer giving the repeating unit (A), a monomer giving the repeating unit (B) and a monomer giving the repeating unit (C), contacting the resulting solution with an ion exchange resin, and, thereafter, copolymerizing the monomers.