A semiconductor device and a method of manufacturing the same are disclosed. The semiconductor device includes semiconductor wires disposed over a substrate, a source/drain epitaxial layer in contact with the semiconductor wires, a gate dielectric layer disposed on and wrapping around each channel region of the semiconductor wires, a gate electrode layer disposed on the gate dielectric layer and wrapping around the each channel region, and dielectric spacers disposed in recesses formed toward the source/drain epitaxial layer.