US Patent 9634149 Semiconductor device and method for manufacturing thereof

A transistor that is formed using an oxide semiconductor film is provided. A transistor that is formed using an oxide semiconductor film with reduced oxygen vacancies is provided. A transistor having excellent electrical characteristics is provided. A semiconductor device includes a first insulating film, a first oxide semiconductor film, a gate insulating film, and a gate electrode. The first insulating film includes a first region and a second region. The first region is a region that transmits less oxygen than the second region does. The first oxide semiconductor film is provided at least over the second region.