Composition for forming tungsten oxide film and method for producing tungsten oxide film using same

1. A composition for forming a tungsten oxide film, comprising water, a water-soluble metatungstate, and at least one additive selected from the group consisting of anionic polymers, nonionic polymers, anionic surfactants, and tertiary amino group-containing nonionic surfactants; said composition being used for forming an image reversal trilayer structure, a resist undercoat layer or a resist top protective film wherein said additive is an anionic polymer represented by the following formula (1):

in which

each Z is independently hydrogen, methyl or fluorine;

L is a divalent linking group selected from the group consisting of single bond, a hydrocarbon group which may contain an oxygen atom provided that the total number of carbon and oxygen atoms is in the range of 1 to 6, and a group in which at least one hydrogen atom in said hydrocarbon group is replaced with a fluorine atom; and

A is —COOM or —SO 3 M in which M is hydrogen ion, ammonium ion or a monovalent metal ion.

2. The composition according to claim 1 for forming a tungsten oxide film; wherein said water-soluble metatungstate is selected from the group consisting of metatungstic acid, ammonium metatungstate, potassium metatungstate, and sodium metatungstate.

3. The composition according to claim 1 for forming a tungsten oxide film, wherein said water-soluble metatungstate is contained in an amount of 10 to 50 wt % based on the total weight of the composition.

4. A composition for forming a tungsten oxide film, comprising water, a water-soluble metatungstate, and at least one additive selected from the group consisting of anionic polymers, nonionic polymers, anionic surfactants, and tertiary amino group-containing nonionic surfactants; said composition being used for forming an image reversal trilayer structure, a resist undercoat layer or a resist top protective film wherein said additive is a nonionic polymer selected from the group consisting of polyvinyl pyrrolidone, polyvinyl alcohol, polyoxazoline, polysaccharides, and derivatives thereof.

5. A composition for forming a tungsten oxide film, comprising water, a water-soluble metatungstate, and at least one additive selected from the group consisting of anionic polymers, nonionic polymers, anionic surfactants, and tertiary amino group-containing nonionic surfactants; said composition being used for forming an image reversal trilayer structure, a resist undercoat layer or a resist top protective film wherein said additive is an anionic surfactant selected from the group consisting of an alkylsulfonic acid which may be fluorine-substituted and which has 4 to 24 carbon atoms, an alkylcarboxylic acid which may be fluorine- substituted and which has 4 to 24 carbon atoms, ammonium salts thereof, potassium salts thereof, and sodium salts thereof.

6. A composition for forming a tungsten oxide film, comprising water, a water-soluble metatungstate, and at least one additive selected from the group consisting of anionic polymers, nonionic polymers, anionic surfactants, and tertiary amino group-containing nonionic surfactants; said composition being used for forming an image reversal trilayer structure, a resist undercoat layer or a resist top protective film wherein said additive is selected from the group consisting of tertiary amino group-containing nonionic surfactants having alkylene oxide adducts.

7. A process for forming a tungsten oxide film, wherein the composition according to claims 1 for forming a tungsten oxide film is cast on a substrate and then fired.

8. The process for forming a tungsten oxide film of claim 7 on a substrate further comprising the steps of

forming a photoresist pattern on said tungsten oxide film;

etching said tungsten oxide film by use of said photoresist pattern as a photomask, so as to transfer the photoresist pattern onto the tungsten oxide film; and

etching said substrate by use of said patterned tungsten oxide film as a photomask.

9. The pattern formation method according to claim 8 , wherein said composition for forming a tungsten oxide film contains said additive in an amount of 0.5 to 20 wt % based on the amount of the metatungstate contained therein.

10. The pattern formation method according to claim 8 , wherein said substrate is previously covered with a carbon hard mask before said composition for forming a tungsten oxide film is cast thereon.

11. The pattern formation method according to claim 8 , wherein said composition for forming a tungsten oxide film is cast and then heated at 200 to 500° C. for 30 to 600 seconds.

12. A pattern formation method comprising the steps of:

forming a hard mask on a substrate;

forming a photoresist pattern according to the aimed pattern on said hard mask;

casting on said photoresist pattern and then heating the composition according to claim 1 for forming a tungsten oxide film, so as to cover said photoresist pattern with a tungsten oxide film;

removing by etching the tungsten oxide film formed in the area on the top surface of said photoresist pattern, so as to bare the top surface of said photoresist pattern; and

removing by etching said photoresist pattern by use of said tungsten oxide film as a photomask, and further transferring said photoresist pattern onto said hard mask.

13. The pattern formation method according to claim 12 , wherein said composition for forming a tungsten oxide film contains said additive in an amount of 0.5 to 20 wt % based on the amount of the metatungstate contained therein.

14. The pattern formation method according to claim 12 , wherein said composition for forming a tungsten oxide film is cast and then heated at 60 to 180° C. for 30 to 300 seconds.

15. A pattern formation method comprising the steps of:

casting a resist composition on a substrate, so as to form a resist layer;

casting on said resist layer and then heating a composition for forming a tungsten oxide film, so as to form a tungsten oxide film and where the composition for forming a tungsten oxide film, comprising water, a water-soluble metatungstate, and at least one additive selected from the group consisting of anionic polymers, nonionic polymers, anionic surfactants, and tertiary amino group-containing nonionic surfactants;

carrying out imagewise exposure; and

carrying out development.

16. The pattern formation method according to claim 15 , wherein said imagewise exposure is carried out by use of light of 1 to 500 nm wavelength.

17. The pattern formation method according to claim 15 , wherein said composition for forming a tungsten oxide film is cast and then heated at 60 to 150° C. for 30 to 300 seconds.