Pattern-forming method

1. A pattern-forming method comprising:

providing a resist film on a substrate using a photoresist composition;

exposing the resist film; and

developing the exposed resist film using a developer having an organic solvent content of 80 mass % or more, the photoresist composition comprising:

a first polymer that is a base polymer and comprises a first structural unit that comprises an acid-labile group;

a second polymer that comprises a second structural unit that comprises an acid-labile group, and has a fluorine atom content higher than a fluorine atom content of the first polymer; and

an acid generator,

the first structural unit being represented by formula (3) or a formula (4),

the second structural unit being represented by formula (1) or a formula (2),

wherein

R 1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group,

Z 1 is a divalent monocyclic hydrocarbon group having 5 or 6 carbon atoms or a divalent polycyclic hydrocarbon group having 7 to 10 carbon atoms,

R 2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and

R 3 is an alicyclic hydrocarbon group having 5 to 20 carbon atoms,

wherein

R 4 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group,

R 5 is an alkyl group having 1 to 5 carbon atoms,

n is 0 or 1,

R 6 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group,

R 7 is an alkyl group having 2 to 5 carbon atoms, and

Z 2 is a divalent monocyclic hydrocarbon group having 5 or 6 carbon atoms or a divalent polycyclic hydrocarbon group having 7 to 15 carbon atoms,

wherein a content of the second polymer is 0.5 to 10 parts by mass based on 100 parts by mass of the first polymer.

2. The pattern-forming method according to claim 1 , wherein the second polymer further comprises a third structural unit represented by formula (5),

wherein

R 8 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group,

X is a linking group, and

R 9 is a linear or branched alkyl group having 1 to 10 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms, wherein some or all of the hydrogen atoms of the alkyl group or the alicyclic hydrocarbon group represented by R 9 are substituted with a substituent, at least one substituent that substitutes some or all of the hydrogen atoms of the alkyl group or the alicyclic hydrocarbon group represented by R 9 being a fluorine atom.

3. The pattern-forming method according to claim 2 , wherein a content of the third structural unit in the second polymer is from 20 to 50 mol % based on total structural units included in the second polymer.

4. The pattern-forming method according to claim 2 , wherein in the formula (5), X represents a single bond, an oxygen atom, a sulfur atom, an ester group, an amide group, a sulfonylamide group, or a urethane group.

5. The pattern-forming method according to claim 1 , wherein in the formula (4), R 7 represents an ethyl group or a propyl group.

6. The pattern-forming method according to claim 1 , wherein in the formula (4), Z 2 represents a cyclopentanediyl group, a cyclohexanediyl group, or an adamantanediyl group.

7. The pattern-forming method according to claim 1 , wherein a content of the first structural unit in the first polymer is from 10 to 90 mol % based on total structural units included in the first polymer.

8. The pattern-forming method according to claim 1 , wherein a content of the first structural unit in the first polymer is from 30 to 60 mol % based on total structural units included in the first polymer.

9. The pattern-forming method according to claim 1 , wherein the first polymer further comprises a structural unit that comprises a lactone structure, a sultone structure, or a cyclic carbonate structure.

10. The pattern-forming method according to claim 8 , wherein a content of the structural unit that comprises a lactone structure, a sultone structure, or a cyclic carbonate structure in the first polymer is from 30 to 60 mol % based on total structural units included in the first polymer.

11. The pattern-forming method according to claim 1 , wherein the first polymer further comprises a structural unit that comprises a polar group.

12. The pattern-forming method according to claim 11 , wherein a content of the structural unit that comprises a polar group in the first polymer is from 10 to 40 mol % based on total structural units included in the first polymer.

13. The pattern-forming method according to claim 1 , wherein a content of the second structural unit in the second polymer is from 10 to 95 mol % based on total structural units included in the second polymer.

14. The pattern-forming method according to claim 1 , wherein a content of the second structural unit in the second polymer is from 40 to 85 mol % based on total structural units included in the second polymer.

15. The pattern-forming method according to claim 1 , wherein an amount of the second polymer is 1 to 10 parts by mass based on 100 parts by mass of the first polymer.

16. The pattern-forming method according to claim 1 , wherein an amount of the second polymer is 1 to 8 parts by mass based on 100 parts by mass of the first polymer.