US Patent 7830703 Semiconductor device and manufacturing method thereof

A semiconductor device having SRAM cell units each comprising a pair of a first driving transistor and a second driving transistor, a pair of a first load transistor and a second load transistor, and a pair of a first access transistor and a second access transistor, wherein each of the transistors comprises a semiconductor layer projecting upward from a substrate plane, a gate electrode extending on opposite sides of the semiconductor layer so as to stride over a top of the semiconductor layer, a gate insulating film interposed between the gate electrode and the semiconductor layer, and a pair of source/drain areas formed in the semiconductor layer; and the first and second driving transistors each have a channel width larger than that of at least either each of the load transistors or each of the access transistors.