Method for manufacturing ferroelectric film

1. A method for manufacturing a ferroelectric film, comprising the steps of:

pouring a sol-gel solution for forming (K 1-X Na X )NbO 3 into a mold;

forming, by calcining said sol-gel solution, a (K 1-X Na X )NbO 3 material film in said mold;

forming, by heat-treating and crystallizing said (K 1-X Na X )NbO 3 material film in an oxygen atmosphere, a (K 1-X Na X )NbO 3 crystallized film in said mold; and

removing said mold through etching, wherein

said mold is more easily etched than said (K 1-X Na X )NbO 3 crystallized film; and

said X satisfies the formula below

0.3≦X≦0.7.

2. The method for manufacturing a ferroelectric film according to claim 1 ,

wherein the total concentration of K, Na and Nb contained in said sol-gel solution is 10 mol % to 50 mol %.

3. The method for manufacturing a ferroelectric film according to claim 1 ,

wherein, when forming said (K 1-X Na X )NbO 3 material film, a (K 1-X Na X )NbO 3 material film is formed by repeating a plurality of times the pouring of said sol-gel solution and said calcination.

4. The method for manufacturing a ferroelectric film according to claim 1 ,

wherein a first crystalline oxide film preferentially oriented to (001) is formed, in a contact state, on at least one of the upper side and lower side of said (K 1-X Na X )NbO 3 crystallized film.

5. The method for manufacturing a ferroelectric film according to claim 4 ,

wherein said first crystalline oxide film is a bismuth layered-structure ferroelectric film having a perovskite structure or a tungsten-bronze type ferroelectric film.

6. The method for manufacturing a ferroelectric film according to claim 5 ,

wherein said bismuth layered-structure ferroelectric film is a Bi 4 Ti 3 O 12 film or a (Bi 3.25 La 0.75 )Ti 3 O 12 film.

7. The method for manufacturing a ferroelectric film according to claim 4 ,

wherein said first crystalline oxide film is formed in an island shape or in a film shape.

8. The method for manufacturing a ferroelectric film according to claim 4 ,

wherein thickness of said first crystalline oxide film is 2 nm to 30 nm.

9. The method for manufacturing a ferroelectric film according to claim 1 ,

wherein said mold is formed of an oxide.

10. The method for manufacturing a ferroelectric film according to claim 9 ,

wherein said oxide is a porous ceramics.

11. The method for manufacturing a ferroelectric film according to claim 9 ,

wherein said oxide is a second crystalline oxide film preferentially oriented to (001).

12. The method for manufacturing a ferroelectric film according to claim 11 ,

wherein said second crystalline oxide film is a bismuth layered-structure ferroelectric film having a perovskite structure or a tungsten-bronze type ferroelectric film.

13. The method for manufacturing a ferroelectric film according to claim 1 ,

wherein said heat treatment is carried out in a pressure range of 0.0993 MPa to 1.986 MPa.

14. A method for manufacturing a ferroelectric film, comprising the steps of:

forming a mold on a substrate;

pouring a sol-gel solution for forming (K 1-X Na X )NbO 3 into said mold;

forming, by calcining said sol-gel solution, a (K 1-X Na X )NbO 3 material film in said mold;

forming, by heat-treating and crystallizing said (K 1-X Na X )NbO 3 material film in an oxygen atmosphere, a (K 1-X Na X )NbO 3 crystallized film in said mold; and

forming, by removing said mold through etching, said (K 1-X Na X )NbO 3 crystallized film on said substrate, wherein

said X satisfies the formula below

0.3≦X≦0.7.

15. The method for manufacturing a ferroelectric film according to claim 14 ,

wherein the total concentration of K, Na and Nb contained in said sol-gel solution is 10 mol % to 50 mol %.

16. The method for manufacturing a ferroelectric film according to claim 14 ,

wherein, when forming said (K 1-X Na X )NbO 3 material film, a (K 1-X Na X )NbO 3 material film is formed by repeating a plurality of times the pouring of said sol-gel solution and said calcination.

17. The method for manufacturing a ferroelectric film according to claim 14 ,

wherein a first crystalline oxide film preferentially oriented to (001) is formed, in a contact state, on at least one of the upper side and lower side of said (K 1-X Na X )NbO 3 crystallized film.

18. The method for manufacturing a ferroelectric film according to claim 14 ,

wherein said mold is formed of an oxide.

19. A method for manufacturing a ferroelectric film, comprising the steps of:

forming a first electrode on a substrate;

forming a mold on said first electrode and said substrate;

pouring a sol-gel solution for forming (K 1-X Na X )NbO 3 into said mold;

forming, by calcining said sol-gel solution, a (K 1-X Na X )NbO 3 material film in said mold;

forming, by heat-treating and crystallizing said (K 1-X Na X )NbO 3 material film in an oxygen atmosphere, (K 1-X Na X )NbO 3 crystallized film in said mold; and

forming, by removing said mold through etching, said (K 1-X Na X )NbO 3 crystallized film on said first electrode, wherein

said X satisfies the formula below

0.3≦X≦0.7.

20. The method for manufacturing a ferroelectric film according to claim 19 , wherein:

after calcining said sol-gel solution and before heat-treating said (K 1-X Na X )NbO 3 material film, an electrode material film is formed on said (K 1-X Na X )NbO 3 material film and said mold; and

by removing said electrode material film positioned on said mold when removing said mold through etching, a second electrode formed of said electrode material film is formed on said (K 1-X Na X )NbO 3 crystallized film.

21. The method for manufacturing a ferroelectric film according to claim 19 ,

wherein the total concentration of K, Na and Nb contained in said sol-gel solution is 10 mol % to 50 mol %.

22. The method for manufacturing a ferroelectric film according to claim 19 ,

wherein, when forming said (K 1-X Na X )NbO 3 material film, a (K 1-X Na X )NbO 3 material film is formed by repeating a plurality of times the pouring of said sol-gel solution and said calcination.

23. The method for manufacturing a ferroelectric film according to claim 19 ,

wherein a first crystalline oxide film preferentially oriented to (001) is formed, in a contact state, on at least one of the upper side and lower side of said (K 1-X Na X )NbO 3 crystallized film.

24. The method for manufacturing a ferroelectric film according to claim 19 ,

wherein said mold is formed of an oxide.

25. A method for manufacturing a ferroelectric film, comprising the steps of:

forming a mold on a substrate;

pouring a first sol-gel solution for forming (K 1-X Na X )NbO 3 into said mold;

forming, by calcining said first sol-gel solution, a first (K 1-X Na X )NbO 3 material film in said mold;

pouring a second sol-gel solution for forming a first crystalline oxide film into said mold;

forming, by calcining said second sol-gel solution, a material film for forming a crystalline oxide film in said mold and on said first (K 1-X Na X )NbO 3 material film;

pouring a third sol-gel solution for forming (K 1-X Na X )NbO 3 into said mold;

forming, by calcining said third sol-gel solution, a second (K 1-X Na X )NbO 3 material film in said mold and on said material film for forming a crystalline oxide film;

forming, by heat-treating and crystallizing said first (K 1-X Na X )NbO 3 material film, said material film for forming a crystalline oxide film and said second (K 1-X Na X )NbO 3 material film in an oxygen atmosphere, a first (K 1-X Na X )NbO 3 crystallized film, a first crystalline oxide film preferentially oriented to (001) and a second (K 1-X Na X )NbO 3 crystallized film stacked in order in said mold; and

removing said mold through etching, wherein

said X satisfies the formula below

0.3≦X≦0.7.

26. The method for manufacturing a ferroelectric film according to claim 25 ,

wherein said first crystalline oxide film is a bismuth layered-structure ferroelectric film having a perovskite structure or a tungsten-bronze type ferroelectric film.

27. The method for manufacturing a ferroelectric film according to claim 25 ,

wherein said first crystalline oxide film is formed in an island shape or in a film shape.

28. The method for manufacturing a ferroelectric film according to claim 25 ,

wherein thickness of said first crystalline oxide film is 2 nm to 30 nm.

29. The method for manufacturing a ferroelectric film according to claim 25 ,

wherein said mold is formed of an oxide.