Inorganic film-forming composition for multilayer resist processes, and pattern-forming method

1. An inorganic film-forming composition, comprising:

a complex that comprises:

metal atoms;

at least one bridging ligand; and

another ligand which is other than the at least one bridging ligand and which is derived from a hydroxy acid ester, a β-diketone, an α-alkyl-substituted acetoacetic acid ester, a β-ketopentanoic acid ester, a benzoylacetic acid ester, a 1,3-acetonedicarboxylic acid diester, a β-dicarboxylic acid ester or a combination thereof; and

a solvent which comprises a monovalent aliphatic alcohol having 4 or more carbon atoms, an alkylene glycol monoalkyl ether having 4 or more carbon atoms, a hydroxy acid ester having 4 or more carbon atoms, a lactone having 4 or more carbon atoms, a monocarboxylic acid ester of an alkylene glycol monoalkyl ether having 6 or more carbon atoms, or a combination thereof,

wherein the at least one bridging ligand comprises a first bridging ligand derived from a compound represented by formula (1):

R 1 X) n   (1)

wherein in the formula (1),

R 1 represents an organic group having a valency of n;

X represents —NCO or —NHR a , wherein R a represents a hydrogen atom or a monovalent organic group; and

n is an integer of 2 to 4,

wherein a plurality of Xs are each identical or different, and

wherein an amount of the first bridging ligand is no less than 50 mol % with respect to a total of the at least one bridging ligand.

2. The inorganic film-forming composition according to claim 1 , wherein the bridging ligand coordinates so as to link the metal atoms.

3. The inorganic film-forming composition according to claim 1 , wherein the metal atoms are atoms from a Group 3 element, a Group 4 element, a Group 5 element, a Group 6 element, a Group 13 element or a combination thereof, and an amount of the metal atoms is no less than 50 mol % with respect to a total of metal atoms and metalloid atoms comprised in the complex.

4. The inorganic film-forming composition according to claim 1 , wherein the first bridging ligand and the another ligand account for no less than 50% of coordination sites of the metal atoms.

5. The inorganic film-forming composition according to claim 1 , wherein a number average molecular weight of the complex is no less than 300 and no greater than 10,000.

6. The inorganic film-forming composition according to claim 1 , wherein an amount of the another ligand with respect to the metal atoms is no less than 10 mol %.

7. The inorganic film-forming composition according to claim 1 , further comprising a crosslinking accelerator.

8. A pattern-forming method comprising:

applying the inorganic film-forming composition according to claim 1 directly or indirectly on a substrate to provide an inorganic film on the substrate;

forming a resist pattern directly or indirectly on the inorganic film; and

forming a pattern on the substrate by at least one dry-etching operation using the resist pattern as a mask.

9. The pattern-forming method according to claim 8 , further comprising providing a resist underlayer film on the substrate,

wherein in providing the inorganic film, the inorganic film is provided on the resist underlayer film.

10. The pattern-forming method according to claim 8 ,

wherein forming the resist pattern comprises:

providing a resist film directly or indirectly on the inorganic film using a resist composition;

exposing the resist film; and

developing the exposed resist film.

11. The pattern-forming method according to claim 10 ,

wherein the resist composition comprises a polymer comprising an acid-labile group, and

wherein a developer solution used in developing the exposed resist film comprises an organic solvent, and a negative type resist pattern is formed.

12. The pattern-forming method according to claim 8 , wherein forming the resist pattern is conducted by nanoimprint lithography.

13. The pattern-forming method according to claim 8 , wherein the metal atoms are atoms from a Group 3 element, a Group 4 element, a Group 5 element, a Group 6 element, a Group 13 element or a combination thereof, and an amount of the metal atoms is no less than 50 mol % with respect to a total of metal atoms and metalloid atoms comprised in the complex.

14. An inorganic film-forming composition, comprising:

a reaction product obtained in a reaction of:

a metal compound that comprises two or more alkoxy ligands;

a compound represented by formula (1); and

a hydroxy acid ester, a β-diketone, an α-alkyl-substituted acetoacetic acid ester, a β-ketopentanoic acid ester, a benzoylacetic acid ester, a 1,3-acetonedicarboxylic acid diester, a β-dicarboxylic acid ester, or a combination thereof; and

a solvent which comprises a monovalent aliphatic alcohol having 4 or more carbon atoms, an alkylene glycol monoalkyl ether having 4 or more carbon atoms, a hydroxy acid ester having 4 or more carbon atoms, a lactone having 4 or more carbon atoms, a monocarboxylic acid ester of an alkylene glycol monoalkyl ether having 6 or more carbon atoms, or a combination thereof,

R 1 X) n   (1)

wherein in the formula (1),

R 1 represents an organic group having a valency of n;

X represents —NCO or —NHR a , wherein R a represents a hydrogen atom or a monovalent organic group; and

n is an integer of 2 to 4,

wherein a plurality of Xs are each identical or different, and

wherein in the reaction product, an amount of a bridging ligand derived from the compound represented by formula (1) is no less than 50 mol % with respect to a total of bridging ligands in the reaction product.

15. The inorganic film-forming composition according to claim 14 , wherein the reaction is carried out in presence of water in an amount of no greater than 50 mol % with respect to the metal compound.

16. The inorganic film-forming composition according to claim 14 , wherein in the reaction product, no less than 50 mol % of the alkoxy ligands comprised in the metal compound are substituted.

17. The inorganic film-forming composition according to claim 14 , wherein the metal atoms are atoms from a Group 3 element, a Group 4 element, a Group 5 element, a Group 6 element, a Group 13 element or a combination thereof, and an amount of the metal atoms is no less than 50 mol % with respect to a total of metal atoms and metalloid atoms comprised in the reaction product.

18. A pattern-forming method comprising:

applying the inorganic film-forming composition according to claim 14 directly or indirectly on a substrate to provide an inorganic film on the substrate;

forming a resist pattern directly or indirectly on the inorganic film; and

forming a pattern on the substrate by at least one dry-etching operation using the resist pattern as a mask.