Pattern-forming method, and radiation-sensitive resin composition

1. A pattern-forming method comprising:

coating a radiation-sensitive resin composition on a substrate to provide a resist film;

exposing the resist film; and

developing the exposed resist film,

wherein a developer solution used in developing the exposed resist film comprises no less than 80% by mass of an organic solvent, and

the radiation-sensitive resin composition comprises:

a radiation-sensitive acid generator; and

a first polymer that comprises a first structural unit, the first structural unit being represented by a formula (1) and having an acid-labile group and an alicyclic group, the acid-labile group being a group that substitutes for a hydrogen atom in a polar functional group, and that is dissociated by an action of an acid generated from the radiation-sensitive acid generator upon exposure, the alicyclic group being capable of avoiding dissociation from a molecular chain by an action of an acid,

wherein, in the formula (1),

R 1 represents a hydrogen atom, a methyl group or a trifluoromethyl group;

R 2 to R 4 each independently represent an alkyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms, or

R 2 represents an alkyl group having 1 to 20 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms, and R 3 and R 4 taken together represent a ring together with the carbon atom to which R 3 and R 4 bond;

CR 2 R 3 R 4 is the acid-labile group;

A represents the alicyclic group having 3 to 20 carbon atoms and having a valency of (n+1), the alicyclic group represented by A being not the acid-labile group;

X represents a single bond, an alkanediyl group having 1 to 20 carbon atoms or an oxyalkanediyl group having 1 to 20 carbon atoms; and

n is an integer of 1 to 3, wherein in a case where n is 2 or greater, a plurality of R 2 s are each identical or different, a plurality of R 3 s are each identical or different and a plurality of R 4 s are each identical or different.

2. The pattern-forming method according to claim 1 , wherein A in the above formula (1) is a group derived from adamantane or norbornane by removing 2 to 4 hydrogen atoms.

3. The pattern-forming method according to claim 1 , wherein the radiation-sensitive resin composition further comprises a second polymer having a content of fluorine atoms higher than a content of fluorine atoms of the first polymer.

4. The pattern-forming method according to claim 1 further comprising etching the developed resist film.

5. The pattern-forming method according to claim 1 , wherein the ring represented by R 3 and R 4 together with the carbon atom to which R 3 and R 4 bond is a divalent cycloalkane group which is unsubstituted or substituted with a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.

6. The pattern-forming method according to claim 5 , wherein the divalent cycloalkane group is a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, or a cycloheptanediyl group, wherein the cyclobutanediyl group, the cyclopentanediyl group, the cyclohexanediyl group, or the cycloheptanediyl group is unsubstituted or substituted with a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.

7. The pattern-forming method according to claim 1 , wherein X in the formula (1) is a single bond, an oxyethylene group or an oxymethylene group.

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

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

wherein R 5 represents a hydrogen atom, a methyl group or a trifluoromethyl group, and R p represents an acid-labile group.

10. The pattern-forming method according to claim 9 , wherein an amount of the second structural unit in the first polymer is from 20 mol % to 60 mol % based on a total amount of structural units constituting the first polymer.

11. The pattern-forming method according to claim 1 , wherein the first polymer further comprises a third structural unit having a lactone ring.

12. The pattern-forming method according to claim 11 , wherein an amount of the third structural unit in the first polymer is from 30 mol % to 80 mol % based on a total amount of structural units constituting the first polymer.