Metal oxide film and semiconductor device

1. A semiconductor device comprising:

a first conductive film over a substrate;

a first insulating film over the first conductive film;

an oxide semiconductor layer over the first insulating film;

a second insulating film over the oxide semiconductor layer;

a second conductive film over the second insulating film;

a third conductive film over the second conductive film; and

a third insulating film over the third conductive film,

wherein the oxide semiconductor layer comprises indium, an element M, and zinc,

wherein the element M is Al, Ga, Y, or Sn,

wherein a plurality of crystal parts is observed in a transmission electron microscope image in a direction perpendicular to a surface of the oxide semiconductor layer,

wherein a proportion of a region other than the plurality of crystal parts is higher than or equal to 20% and lower than or equal to 60%, and

wherein the third insulating film has a region in contact with a top surface of the oxide semiconductor layer and a top surface of the first insulating film.

2. The semiconductor device according to claim 1 ,

wherein the plurality of crystal parts has a higher proportion of crystal parts in which c-axes are aligned in a thickness direction of the oxide semiconductor layer than crystal parts aligned in other directions.

3. The semiconductor device according to claim 1 ,

wherein a first image is an image obtained by subjecting a cross-sectional TEM image to fast Fourier transform,

wherein a second image is obtained by subjecting the first image to inverse fast Fourier transform after mask treatment by which a periodic region remains,

wherein in the second image, the proportion of the remaining area subtracted from an original image is more than or equal to 20% and less than 60%.

4. The semiconductor device according to claim 1 , wherein the proportion of the region other than the plurality of crystal parts is higher than or equal to 30% and lower than or equal to 50%.

5. The semiconductor device according to claim 1 ,

wherein when electron diffraction with a probe diameter of 50 nm or more is performed on a slice of the oxide semiconductor layer having a thickness of greater than or equal to 10 nm and less than or equal to 50 nm in the direction perpendicular to its cross section, a first electron diffraction pattern that includes a ring-like diffraction pattern and two first spots overlapping with the ring-like diffraction pattern is observed, and

wherein when electron diffraction with a probe diameter of greater than or equal to 0.3 nm and less than or equal to 5 nm is performed thereon, a second electron diffraction pattern that includes the two first spots and a plurality of second spots distributed in a circumferential direction is observed.

6. The semiconductor device according to claim 5 ,

wherein the two first spots are symmetric with respect to a center,

wherein an angle between a first straight line and the direction of a normal vector of the surface of the oxide semiconductor layer is more than or equal to 0° and less than or equal to 10°, and

wherein the first straight line passes through the center and a point at which a luminance of the two first spots is the highest.

7. The semiconductor device according to claim 6 ,

wherein in the first electron diffraction pattern, the luminance of the ring-like diffraction pattern is lower than that of the two first spots at a point of intersection of the ring-like diffraction pattern and a second straight line that intersects with the first straight line.

8. The semiconductor device according to claim 7 ,

wherein the luminance of the two first spots is greater than 1 time and less than or equal to 9 times the luminance of the ring-like diffraction pattern at the point of intersection of the ring-like diffraction pattern and the second straight line.

9. A semiconductor device comprising:

a first conductive film over a substrate;

a first insulating film over the first conductive film;

an oxide semiconductor layer over the first insulating film;

a second insulating film over the oxide semiconductor layer;

a second conductive film over the second insulating film;

a third conductive film over the second conductive film; and

a third insulating film over the third conductive film,

wherein the oxide semiconductor layer comprises indium, an element M, and zinc,

wherein the element M is Al, Ga, Y, or Sn,

wherein a plurality of crystal parts is observed in a transmission electron microscope image in a direction perpendicular to a surface of the oxide semiconductor layer,

wherein a proportion of a region other than the plurality of crystal parts is higher than or equal to 20% and lower than or equal to 60%,

wherein the third insulating film has a region in contact with a top surface of the oxide semiconductor layer and a top surface of the first insulating film, and

wherein a length of the second insulating film is longer than a length of the second conductive film in a cross sectional view of the semiconductor device.

10. The semiconductor device according to claim 9 ,

wherein the plurality of crystal parts has a higher proportion of crystal parts in which c-axes are aligned in a thickness direction of the oxide semiconductor layer than crystal parts aligned in other directions.

11. The semiconductor device according to claim 9 ,

wherein a first image is an image obtained by subjecting a cross-sectional TEM image to fast Fourier transform,

wherein a second image is obtained by subjecting the first image to inverse fast Fourier transform after mask treatment by which a periodic region remains,

wherein in the second image, the proportion of the remaining area subtracted from an original image is more than or equal to 20% and less than 60%.

12. The semiconductor device according to claim 9 , wherein the proportion of the region other than the plurality of crystal parts is higher than or equal to 30% and lower than or equal to 50%.

13. The semiconductor device according to claim 9 ,

wherein when electron diffraction with a probe diameter of 50 nm or more is performed on a slice of the oxide semiconductor layer having a thickness of greater than or equal to 10 nm and less than or equal to 50 nm in the direction perpendicular to its cross section, a first electron diffraction pattern that includes a ring-like diffraction pattern and two first spots overlapping with the ring-like diffraction pattern is observed, and

wherein when electron diffraction with a probe diameter of greater than or equal to 0.3 nm and less than or equal to 5 nm is performed thereon, a second electron diffraction pattern that includes the two first spots and a plurality of second spots distributed in a circumferential direction is observed.

14. The semiconductor device according to claim 13 ,

wherein the two first spots are symmetric with respect to a center,

wherein an angle between a first straight line and the direction of a normal vector of the surface of the oxide semiconductor layer is more than or equal to 0° and less than or equal to 10°, and

wherein the first straight line passes through the center and a point at which a luminance of the two first spots is the highest.

15. The semiconductor device according to claim 14 ,

wherein in the first electron diffraction pattern, the luminance of the ring-like diffraction pattern is lower than that of the two first spots at a point of intersection of the ring-like diffraction pattern and a second straight line that intersects with the first straight line.

16. The semiconductor device according to claim 15 ,

wherein the luminance of the two first spots is greater than 1 time and less than or equal to 9 times the luminance of the ring-like diffraction pattern at the point of intersection of the ring-like diffraction pattern and the second straight line.