OXIDE FOR SEMICONDUCTOR LAYER OF THIN-FILM TRANSISTOR, SEMICONDUCTOR LAYER OF THIN-FILM TRANSISTOR HAVING SAID OXIDE, AND THIN-FILM TRANSISTOR

摘要

The oxide of the present invention for thin-film transistors is an In—Zn—Sn-based oxide containing In, Zn, and Sn, wherein when the respective contents (atomic %) of metal elements contained in the In—Zn—Sn-based oxide are expressed by [Zn], [Sn], and [In], the In—Zn—Sn-based oxide fulfills the following expressions (2) and (4) when [In]/([In]+[Sn])≦0.5; or the following expressions (1), (3), and (4) when [In]/([In]+[Sn])0.5. [In]/([In]+[Zn]+[Sn])≦0.3 - - - (1), [In]/([In]+[Zn]+[Sn])≦1.4×{[Zn]/([Zn]+[Sn])}−0.5 - - - (2), [Zn]/([In]+[Zn]+[Sn])≦0.83 - - - (3), and 0.1≦[In]/([In]+[Zn]+[Sn]) - - - (4). According to the present invention, oxide thin films for thin-film transistors can be obtained, which provide TFTs with excellent switching characteristics, and which have high sputtering rate in the sputtering and properly controlled etching rate in the wet etching.