Metal oxide film, method for forming same, and semiconductor device

Provided is a metal oxide film which is capable of being formed at a low temperature, and which exhibits excellent electrical characteristics. Provided is a metal oxide film with which electric field effect mobility is improved. Provided is a semiconductor device which is capable of being formed at a low temperature, and which exhibits high electric field effect mobility. The metal oxide includes In, M (M being Al, Ga, Y, or Sn), and Zn, and includes regions in which the proportion of In is greater than 33% but not more than 60%, when the sum total of the composition including each of In, M, and Zn is 1. Furthermore, the metal oxide includes: crystal portions which have no orientation, and which have a size of not more than 10 nm; and amorphous regions. Moreover, a region is present in which a diffraction intensity peak caused by the crystalline structure is not observed in the vicinity of 2θ=31˚ in X-ray diffraction performed in a direction orthogonal to the film surface. Additionally, a region is present in which a circularly symmetric pattern is observed in electron diffraction performed in a direction orthogonal to the cross section.