Metal oxide film and method for forming metal oxide film

1. A method for manufacturing a metal oxide film comprising:

forming the metal oxide film by a sputtering method using a sputtering target comprising a polycrystalline oxide in an atmosphere where oxygen partial pressure is greater than or equal to 33%,

wherein the sputtering target comprises indium, gallium and zinc,

wherein the metal oxide film comprises a plurality of crystal parts when the metal oxide film is formed,

wherein a size of one of the plurality of crystal parts is less than or equal to 10 nm, and

wherein a crystal peak is not observable in an XRD spectrum with respect to the metal oxide film.

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

wherein the size of the one of the plurality of crystal parts is less than or equal to 5 nm.

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

wherein the XRD spectrum is measured by an out-of-plane method.

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

wherein the metal oxide film is formed without heating a substrate on which the metal oxide film is formed.

5. The method for manufacturing a metal oxide film according to claim 1 , further comprising,

performing a first heat treatment in an atmosphere comprising nitrogen, and

performing a second heat treatment in an atmosphere comprising nitrogen and oxygen.

6. A method for manufacturing a metal oxide film comprising:

forming the metal oxide film by a sputtering method using a sputtering target comprising a polycrystalline oxide in an atmosphere where oxygen partial pressure is greater than or equal to 33%,

wherein the sputtering target comprises indium, gallium and zinc,

wherein the metal oxide film comprises a crystal part when the metal oxide film is formed,

wherein a size of the crystal part is less than or equal to 10 nm,

wherein a crystal peak is not observable in an XRD spectrum with respect to the metal oxide film, and

wherein a plurality of circumferentially distributed spots are observable in a measurement area greater than or equal to an area with a diameter of 5 nmφ and less than or equal to an area with a diameter of 10 nmφ in a nanobeam electron diffraction pattern of a cross-section of the metal oxide film.

7. The method for manufacturing a metal oxide film according to claim 6 ,

wherein there is no difference between the first plurality of circumferentially distributed spots and a second plurality of circumferentially distributed spots which are observable in a nanobeam electron diffraction of a cross-section in which a measurement area is 5 nmϕ or more and 10 nmϕ or less with respect to the same metal oxide film after being irradiated with an electron beam whose beam diameter is converged to about 1 nmϕ for one minute.

8. The method for manufacturing a metal oxide film according to claim 7 ,

wherein an acceleration voltage for the electron beam is 200 kV.

9. The method for manufacturing a metal oxide film according to claim 6 ,

wherein the size of the crystal part is less than or equal to 5 nm.

10. The method for manufacturing a metal oxide film according to claim 6 ,

wherein the XRD spectrum is measured by an out-of-plane method.

11. The method for manufacturing a metal oxide film according to claim 6 ,

wherein the metal oxide film is formed without heating a substrate on which the metal oxide film is formed.

12. The method for manufacturing a metal oxide film according to claim 6 , further comprising,

performing a first heat treatment in an atmosphere comprising nitrogen, and

performing a second heat treatment in an atmosphere comprising nitrogen and oxygen.

13. A method for manufacturing a metal oxide film comprising:

forming the metal oxide film by a sputtering method using a sputtering target comprising a polycrystalline oxide in an atmosphere where oxygen partial pressure is greater than or equal to 33%,

wherein the sputtering target comprises indium, gallium and zinc,

wherein the metal oxide film comprises a crystal part when the metal oxide film is formed,

wherein a size of the crystal part is less than or equal to 10 nm,

wherein a crystal peak is not observable in an XRD spectrum with respect to the metal oxide film,

wherein a plurality of circumferentially distributed spots are observable in a measurement area greater than or equal to an area with a diameter of 5 nmφ and less than or equal to an area with a diameter of 10 nmφ in a nanobeam electron diffraction pattern of a cross-section of the metal oxide film, and

wherein a halo pattern is observable in a selected-area electron diffraction pattern of a plane of the metal oxide film.

14. The method for manufacturing a metal oxide film according to claim 13 ,

wherein there is no difference between the first plurality of circumferentially distributed spots and a second plurality of circumferentially distributed spots which are observable in a nanobeam electron diffraction of a cross-section in which a measurement area is 5 nmϕ or more and 10 nmϕ or less with respect to the same metal oxide film after being irradiated with an electron beam whose beam diameter is converged to about 1 nmϕ for one minute.

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

wherein an acceleration voltage for the electron beam is 200 kV.

16. The method for manufacturing a metal oxide film according to claim 13 ,

wherein the size of the crystal part is less than or equal to 5 nm.

17. The method for manufacturing a metal oxide film according to claim 13 ,

wherein the XRD spectrum is measured by an out-of-plane method.

18. The method for manufacturing a metal oxide film according to claim 13 ,

wherein the metal oxide film is formed without heating a substrate on which the metal oxide film is formed.

19. The method for manufacturing a metal oxide film according to claim 13 , further comprising,

performing a first heat treatment in an atmosphere comprising nitrogen, and

performing a second heat treatment in an atmosphere comprising nitrogen and oxygen.