| abstract |
An oxide semiconductor layer with a reduced amount of defects is provided. In addition, a semiconductor device using an oxide semiconductor and having high reliability is provided. A first oxide semiconductor layer having a crystal part is formed on a substrate by a sputtering method, and the first oxide semiconductor layer is epitaxially grown as a seed crystal on the first oxide semiconductor layer. The second oxide semiconductor layer is formed by a thermal chemical vapor deposition method. In addition, a channel is formed in the second oxide semiconductor layer. [Selection] Figure 1 |