US Patent 7256078 High mobility plane FinFETs with equal drive strength

An integrated circuit structure has a buried oxide (BOX) layer above a substrate, and a first-type fin-type field effect transistor (FinFET) and a second-type FinFET above the BOX layer. The second region of the BOX layer includes a seed opening to the substrate. The top of the first-type FinFET and the second-type FinFET are planar with each other. A first region of the BOX layer below the first FinFET fin is thicker above the substrate when compared to a second region of the BOX layer below the second FinFET fin. Also, the second FinFET fin is taller than the first FinFET fin. The height difference between the first fin and the second fin permits the first-type FinFET to have the same drive strength as the second-type FinFET.