Oxide semiconductor film, method for forming oxide semiconductor film, and semiconductor device

1. An oxide semiconductor film comprising:

a plurality of plate particles each having a structure in which layers including a gallium atom, a zinc atom, and an oxygen atom are provided over and under a layer including an indium atom and an oxygen atom,

wherein the plurality of plate particles is arranged irregularly.

2. The oxide semiconductor film according to claim 1 , wherein a crystal boundary in the oxide semiconductor film is not observed by using a transmission electron microscope.

3. The oxide semiconductor film according to claim 1 , wherein the plurality of plate particles each has a thickness of greater than or equal to 0.5 nm and less than or equal to 0.9 nm and an equivalent circle diameter of a plane of greater than or equal to 1 nm and less than or equal to 3 nm.

4. The oxide semiconductor film according to claim 1 , wherein the plurality of plate particles each has regularity in atomic arrangement.

5. The oxide semiconductor film according to claim 1 , wherein a plurality of circumferentially distributed spots is observed in a nanobeam electron diffraction pattern of the oxide semiconductor film.

6. The oxide semiconductor film according to claim 5 , wherein a probe diameter of an electron beam is larger than or equal to 1 nm and smaller than or equal to 30 nm.

7. An semiconductor device comprising:

a gate electrode;

an oxide semiconductor film;

a gate insulating layer between the gate electrode and the oxide semiconductor film; and

a source electrode and a drain electrode each electrically connected to the oxide semiconductor film,

wherein the oxide semiconductor film comprises a plurality of plate particles each having a structure in which layers including a gallium atom, a zinc atom, and an oxygen atom are provided over and under a layer including an indium atom and an oxygen atom, and

wherein the plurality of plate particles is arranged irregularly.

8. The semiconductor device according to claim 7 , wherein a crystal boundary in the oxide semiconductor film is not observed by using a transmission electron microscope.

9. The semiconductor device according to claim 7 , wherein the plurality of plate particles each has a thickness of greater than or equal to 0.5 nm and less than or equal to 0.9 nm and an equivalent circle diameter of a plane of greater than or equal to 1 nm and less than or equal to 3 nm.

10. The semiconductor device according to claim 7 , wherein the plurality of plate particles each has regularity in atomic arrangement.

11. The semiconductor device according to claim 7 , wherein a plurality of circumferentially distributed spots is observed in a nanobeam electron diffraction pattern of the oxide semiconductor film.

12. The semiconductor device according to claim 11 , wherein a probe diameter of an electron beam is larger than or equal to 1 nm and smaller than or equal to 30 nm.

13. A method for forming an oxide semiconductor film, comprising steps of:

separating a plurality of plate particles from a target including indium, gallium, and zinc, wherein the plurality of plate particles each has a structure in which layers including a gallium atom, a zinc atom, and an oxygen atom are provided over and under a layer including an indium atom and an oxygen atom; and

depositing the plurality of plate particles over a substrate irregularly.

14. The method for forming an oxide semiconductor film according to claim 13 , wherein a temperature of the substrate is higher than or equal to 15° C. and lower than or equal to 35° C.

15. The method for forming an oxide semiconductor film according to claim 13 , wherein the target including indium, gallium, and zinc has a composition formula of InGaZnO 4 .

16. The method for forming an oxide semiconductor film according to claim 13 , wherein the separation of the plurality of plate particles occurs by collision of an ion with the target.

17. The oxide semiconductor film according to claim 1 , wherein a halo pattern is observed in a selected-area electron diffraction pattern of the oxide semiconductor film.

18. The semiconductor device according to claim 7 , wherein a halo pattern is observed in a selected-area electron diffraction pattern of the oxide semiconductor film.

19. The method for forming an oxide semiconductor film according to claim 13 , wherein a halo pattern is observed in a selected-area electron diffraction pattern of the oxide semiconductor film.