Abstract: A semiconductor device with a small variation in characteristics is provided. The semiconductor device includes an oxide, a first conductor and a second conductor over the oxide, a first insulator over the first conductor, a second insulator over the second conductor, a third conductor over the first insulator, a fourth insulator over the second insulator, a fifth insulator over the third insulator and the fourth insulator, a sixth insulator over the fifth insulator, a seventh insulator that is over the oxide and placed between the first conductor and the second conductor, an eighth insulator over the seventh insulator, a third conductor over the eighth insulator, and a ninth insulator over the third conductor and the sixth to eighth insulators. The third conductor includes a region overlapping the oxide. The seventh insulator includes a region in contact with each of the oxide, the first conductor, the second conductor, and the first to sixth insulators.

Abstract: A transistor in which an electron state at an interface between an oxide semiconductor film and an underlayer film in contact with the oxide semiconductor film is favorable is provided. A value obtained by dividing a difference between nearest neighbor interatomic distance of the underlayer film within the interface and a lattice constant of the semiconductor film by the nearest neighbor interatomic distance of the underlayer film within the interface is less than or equal to 0.15. For example, an oxide semiconductor film is deposited over an underlayer film which contains stabilized zirconia which has a cubic crystal structure and has the (111) plane orientation, whereby the oxide semiconductor film including a crystal region having a high degree of crystallization can be provided directly on the underlayer film.

Abstract: A transistor in which an electron state at an interface between an oxide semiconductor film and an underlayer film in contact with the oxide semiconductor film is favorable is provided. A value obtained by dividing a difference between nearest neighbor interatomic distance of the underlayer film within the interface and a lattice constant of the semiconductor film by the nearest neighbor interatomic distance of the underlayer film within the interface is less than or equal to 0.15. For example, an oxide semiconductor film is deposited over an underlayer film which contains stabilized zirconia which has a cubic crystal structure and has the (111) plane orientation, whereby the oxide semiconductor film including a crystal region having a high degree of crystallization can be provided directly on the underlayer film.