US Patent 10269968 Semiconductor device including fin structures and manufacturing method thereof

A method of manufacturing a semiconductor Fin FET includes forming a fin structure over a substrate. The fin structure includes an upper layer, part of which is exposed from an isolation insulating layer. A dummy gate structure is formed over part of the fin structure. The dummy gate structure includes a dummy gate electrode layer and a dummy gate dielectric layer. A source and a drain are formed. The dummy gate electrode is removed so that the upper layer covered by the dummy gate dielectric layer is exposed. The upper layer of the fin structure is removed to make a recess formed by the dummy gate dielectric layer. Part of the upper layer remains at a bottom of the recess. A channel layer is formed in the recess. The dummy gate dielectric layer is removed. A gate structure is formed over the channel layer.