A method for producing a thin film includes the following steps: providing a primary substrate; forming an etching stop layer on the primary substrate; forming a sacrificial layer on the etching stop layer; implanting gas ions to form an ion implantation peak layer, which defines an effective transferred layer and a remnant layer; and separating the effective transferred layer from the remnant layer. The thickness of the effective transferred layer can be effectively determined by controlling the thickness of the sacrificial layer. Moreover, the thickness of the effective transferred layer can be uniform and then the effective transferred layer can become a nanoscale thin film.