Copolymer and positive resist composition
Provided is a copolymer that can be favorably used as a main chain scission-type positive resist that has excellent heat resistance and that can form a resist pattern having excellent resolution and clarity. The copolymer includes a monomer unit (A) represented by the following formula (I) and a monomer unit (B) represented by the following formula (II), and has a molecular weight distribution of 1.7 or less. In the formulae, L is a single bond or a divalent linking group, Ar is an optionally substituted aromatic ring group, R 1 is an alkyl group, R 2 is an alkyl group, a halogen atom, or a haloalkyl group, p is an integer of not less than 0 and not more than 5, and in a case in which more than one R 2 is present, each R 2 may be the same or different.
1. A copolymer comprising:
a monomer unit (A) represented by formula (I), shown below,
where, in formula (I), L is an optionally substituted alkylene group and Ar is an optionally substituted aromatic ring group; and
a monomer unit (B) represented by formula (II), shown below,
where, in formula (II), R 1 is an alkyl group, R 2 is an alkyl group, a halogen atom, or a haloalkyl group, p is an integer of not less than 0 and not more than 5, and in a case in which more than one R 2 is present, each R 2 may be the same or different, wherein
the copolymer has a molecular weight distribution of 1.7 or less.
2. The copolymer according to claim 1 , having a weight-average molecular weight of 80,000 or less.
3. A positive resist composition comprising: the copolymer according to claim 1 ; and a solvent.
4. A copolymer comprising:
a monomer unit (A) represented by formula (I), shown below,
where, in formula (I), L is a divalent linking group that includes an electron withdrawing group and Ar is an optionally substituted aromatic ring group; and
a monomer unit (B) represented by formula (II), shown below,
where, in formula (II), R 1 is an alkyl group, R 2 is an alkyl group, a halogen atom, or a haloalkyl group, p is an integer of not less than 0 and not more than 5, and in a case in which more than one R 2 is present, each R 2 may be the same or different, wherein
the copolymer has a molecular weight distribution of 1.7 or less.
5. The copolymer according to claim 4 , wherein the electron withdrawing group is at least one selected from the group consisting of a fluorine atom, a fluoroalkyl group, a cyano group, and a nitro group.
6. The copolymer according to claim 4 , having a weight-average molecular weight of 80,000 or less.
7. A positive resist composition comprising: the copolymer according to claim 4 ; and a solvent.
8. A copolymer comprising:
a monomer unit (A) and a monomer unit (B),
the monomer unit (A) is a 1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl α-chloroacrylate unit or a benzyl α-chloroacrylate unit, and
the monomer unit (B) is an α-methylstyrene unit or a 4-fluoro-α-methylstyrene unit wherein the copolymer has a molecular weight distribution of 1.7 or less.
9. The copolymer according to claim 8 , having a weight-average molecular weight of 80,000 or less.
10. A positive resist composition comprising: the copolymer according to claim 8 ; and a solvent.