Semiconductor device and method for producing the same

Abstract

One of the upper surface and the lower surface of a semiconductor layer () of a thin-film transistor () in a semiconductor device () is in contact with a gate insulating layer (), and the other is in contact with a first insulating layer () containing silicon oxide. The semiconductor layer () includes a first and second oxide semiconductor layers (A,B). The first oxide semiconductor layer (A) is arranged on a gate insulating layer side of the second oxide semiconductor layer (B) and is in contact with the second oxide semiconductor layer. The second oxide semiconductor layer (B) contains In and Ga and does not contain Sn. The first oxide semiconductor layer (A) contains In, Sn, and Zn. The percentage of Zn in the first oxide semiconductor layer (A) in the depth direction does not have a maximum value in the vicinity of a surface of the first oxide semiconductor layer adjacent to the second oxide semiconductor layer. The percentage of Sn having a metallic bonding state at the interface between the first oxide semiconductor layer and the second oxide semiconductor layer is 90% or less with respect to the total amount of Sn. A region where the percentage is 50% or more has a thickness of less than 10 nm.