US Patent 9735274 Semiconductor device including a stacked wire structure

A semiconductor device structure is provided. The semiconductor device structure includes a substrate and a stacked wire structure formed over the substrate. The semiconductor device structure also includes a gate structure formed over a middle portion of the stacked wire structure and a source/drain (S/D) structure formed at two opposite sides of the stacked wire structure. The S/D structure includes a top surface, a sidewall surface, and a rounded corner between the top surface and the sidewall surface.