Semiconductor device and manufacturing method thereof, SOI substrate and display device using the same, and manufacturing method of the SOI substrate

A polycrystalline Si thin film and a single crystal Si thin film are formed on an SiO2 film deposited on an insulating substrate. A polycrystalline Si layer is grown by thermally crystallizing an amorphous Si thin film so as to form the polycrystalline Si thin film. A single crystal Si substrate, having (a) an SiO2 film thereon and (b) a hydrogen ion implantation portion therein, is bonded to an area of the polycrystalline Si thin film that has been subjected to etching removal, and is subjected to a heating process. Then, the single crystal Si substrate is divided at the hydrogen ion implantation portion in an exfoliating manner, so as to form the single crystal Si thin film. As a result, it is possible to provide a large-size semiconductor device, having the single crystal Si thin film, whose property is stable, at a low cost.