Metal oxide film and semiconductor device
A metal oxide film includes indium, M, (M is Al, Ga, Y, or Sn), and zinc and includes a region where a peak having a diffraction intensity derived from a crystal structure is observed by X-ray diffraction in the direction perpendicular to the film surface. Moreover, a plurality of crystal parts is observed in a transmission electron microscope image in the direction perpendicular to the film surface. The proportion of a region other than the crystal parts is higher than or equal to 20% and lower than or equal to 60%.
1. A metal oxide film comprising:
indium;
M which is Al, Ga, Y, or Sn; and
zinc,
wherein a peak having a diffraction intensity derived from a crystal structure is observed by X-ray diffraction in a direction perpendicular to a surface of the metal oxide film,
wherein a plurality of crystal parts is observed in a transmission electron microscope image in the direction perpendicular to the surface of the metal oxide film, and
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%.
2. The metal oxide film 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 than crystal parts aligned in other directions.
3. The metal oxide film according claim 1 ,
wherein in a second image obtained in such a manner that a first image that is an image obtained by subjecting a cross-sectional TEM image to fast Fourier transform is subjected to inverse fast Fourier transform after mask treatment by which a periodic region remains, the proportion of the remaining area subtracted from an original image is more than or equal to 20% and less than 60%.
4. The metal oxide film according to claim 1 ,
wherein when electron diffraction with a probe diameter of 50 nm or more is performed on a slice of the metal oxide film 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 diffiaction pattern that includes the two first spots and a plurality of second spots distributed in a circumferential direction is observed.
5. The metal oxide film according to claim 4 ,
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 metal oxide film 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 the luminance of the two first spots is the highest.
6. The metal oxide film according to claim 5 ,
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 diffiaction pattern and a second straight line that intersects with the first straight line.
7. The metal oxide film according to claim 6 ,
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.
8. A semiconductor device comprising:
a semiconductor layer;
a gate insulating layer; and
a gate,
wherein the semiconductor layer includes the metal oxide film according to claim 1 .