Resist pattern-forming method, substrate-processing method, and photoresist composition

1. A resist pattern-forming method, comprising:

applying a photoresist composition on a substrate to provide a resist film on the substrate;

exposing the resist film to a KrF excimer laser beam through a predetermined mask pattern; and

developing the resist film exposed,

the photoresist composition comprising:

a polymer having a weight average molecular weight of no less than 3,000 and no greater than 7,000 and comprising a structural unit that comprises an acid-labile group that is dissociated by an action of an acid;

a radiation-sensitive acid generator; and

a solvent composition, and

the photoresist composition having a content of solids of no less than 20% by mass and no greater than 60% by mass,

wherein a content of the polymer in the photoresist composition with respect to total solid components of the photoresist composition is no less than 70% by mass.

2. The resist pattern-forming method according to claim 1 , wherein the photoresist composition has a viscosity of no less than 50 mPa·s and no greater than 150 mPa·s at 25° C.

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

wherein in the formula (1-1):

R 1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;

R 2 represents a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms;

a is an integer of 1 to 3; and

b is an integer of 0 to 3, wherein a sum of a and b is no greater than 5, and wherein in a case where b is no less than 2, a plurality of R 2 s are identical or different.

4. The resist pattern-forming method according to claim 3 , wherein a proportion of the structural unit represented by the formula (1-1) with respect to the total structural units constituting the polymer is no less than 20 mol % and no greater than 90 mol %.

5. The resist pattern-forming method according to claim 1 , wherein the film thickness of the resist film in the providing a resist film is no less than 2 μm and no greater than 20 μm.

6. The resist pattern-forming method according to claim 1 , wherein the solvent composition comprises a first solvent having a viscosity of no greater than 1.5 mPa·s at 20° C.,

wherein a content of the first solvent in the total solvent composition is no less than 60% by mass.

7. A substrate-processing method, comprising:

applying a photoresist composition on a substrate to provide a resist film on the substrate;

exposing the resist film to an electromagnetic wave or a charged particle ray through a predetermined mask pattern;

developing the resist film exposed to form a resist pattern;

etching the substrate using the resist pattern as a mask;

baring a part of an upper face of the substrate by etching the resist pattern after the etching of the substrate; and

thereafter repeating the etching of the substrate and the baring at least once in this order,

the photoresist composition comprising:

a polymer having a weight average molecular weight of no less than 1,000 and no greater than 7,500 and comprising a structural unit that comprises an acid-labile group that is dissociated by an action of an acid;

a radiation-sensitive acid generator; and

a solvent composition, and

the photoresist composition having a content of solids of no less than 20% by mass and no greater than 60% by mass.

8. A photoresist composition, comprising:

a polymer comprising a structural unit that comprises an acid-labile group that is dissociated by an action of an acid;

a radiation-sensitive acid generator; and

a solvent composition which comprises:

a first solvent having a viscosity of no greater than 1.5 mPa·s at 20° C., a content of the first solvent in the solvent composition is no less than 60% by mass; and

a second solvent comprising a compound that comprises a hydroxy group, a cyclic ketone compound or a combination thereof,

the polymer having a weight average molecular weight of no less than 1,000 and no greater than 7,500,

the structural unit being represented by formula (1-2) or formula (1-4), and

the photoresist composition having a content of solids of no less than 20% by mass and no greater than 60% by mass,

wherein in the formula (1-2):

R 3 represents a hydrogen atom or a methyl group;

R 4 represents a monovalent organic group that does not comprise an acid-labile group;

c is an integer of 0 to 3, wherein in case where c is no less than 2, a plurality of R 4 s are identical or different;

R 5 represents a monovalent acid-labile group; and

d is an integer of 1 to 3, wherein in a case where d is no less than 2, a plurality of les are identical or different, and wherein a sum of c and d is no greater than 5, and

wherein in the formula (1-4):

R 8 represents a hydrogen atom or a methyl group; and

R 9 represents a monovalent acid-labile group.

9. The photoresist composition according to claim 8 , having a viscosity of no less than 50 mPa·s and no greater than 150 mPa·s at 25° C.

10. The photoresist composition according to claim 8 , wherein the first solvent comprises an ester compound, a linear ketone compound or a combination thereof.

11. The photoresist composition according to claim 8 , wherein the first solvent comprises an alkylene glycol monoalkyl ether acetate.

12. The photoresist composition according to claim 8 , wherein the polymer further comprises a structural unit represented by formula (1-1),

wherein in the formula (1-1):

R 1 represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;

R 2 represents a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 12 carbon atoms, or a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms;

a is an integer of 1 to 3; and

b is an integer of 0 to 3, wherein a sum of a and b is no greater than 5, and wherein in a case where b is no less than 2, a plurality of R 2 s are identical or different.

13. The photoresist composition according to claim 12 , wherein a proportion of the structural unit represented by the formula (1-1) with respect to the total structural units constituting the polymer is no less than 20 mol % and no greater than 90 mol %.

14. The photoresist composition according to claim 8 , wherein a proportion of a structural unit that comprises an aromatic ring with respect to the total structural units constituting the polymer is no less than 50 mol %.

15. A photoresist composition, comprising:

a polymer comprising a structural unit that comprises an acid-labile group that is dissociated by an action of an acid;

a radiation-sensitive acid generator; and

a solvent composition,

the polymer having a weight average molecular weight of no less than 1,000 and no greater than 7,500,

the structural unit being represented by formula (1-4), and

the photoresist composition having a content of solids of no less than 20% by mass and no greater than 60% by mass,

wherein in the formula (1-4):

R 8 represents a hydrogen atom or a methyl group; and

R 9 represents a monovalent acid-labile group, and

wherein the solvent composition comprises: a first solvent having a viscosity of no greater than 1.5 mPa·s at 20° C., and a second solvent comprising a compound that comprises a hydroxy group, a cyclic ketone compound or a combination thereof, and

a content of the first solvent in the total solvent composition is no less than 60% by mass.

16. The photoresist composition according to claim 15 , wherein the photoresist composition has a viscosity of no less than 50 mPa·s and no greater than 150 mPa·s at 25° C.

17. The photoresist composition according to claim 15 , wherein the first solvent comprises an ester compound, a linear ketone compound or a combination thereof.

18. The photoresist composition according to claim 15 , wherein the first solvent comprises an alkylene glycol monoalkyl ether acetate.

19. The photoresist composition according to claim 15 , wherein a content of the polymer in the photoresist composition with respect to total solid components of the photoresist composition is no less than 70% by mass.

20. The photoresist composition according to claim 19 , wherein the weight average molecular weight of the polymer is no less than 3,000 and no greater than 7,000.