A method for manufacturing a semiconductor device is provided, including forming a plurality of fins on a semiconductor substrate, and forming source/drain regions on the fins. The source/drain regions have an uneven surface with a mean surface roughness, Ra, of about 10 nm to about 50 nm. A smoothing layer is formed on the source/drain regions filling the uneven surface. An etch stop layer is formed overlying the smoothing layer. A portion of the etch stop layer is removed to expose a portion of the smoothing layer. The exposed smoothing layer is removed, and a contact layer is formed on the source/drain regions.