Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a gate structure located on a substrate, comprising:
• a gate dielectric;
• a gate electrode over the gate dielectric;
• and
• a sidewall spacer laterally abutting the gate dielectric and the gate electrode;
• a raised conductive region adjacent to and partially under the gate structure, wherein the raised conductive region comprises:
• a first epitaxial-grown doped layer of the raised conductive region in contact with the substrate, the first epitaxial-grown doped layer including an elbow angle under the gate dielectric and the first epitaxial-grown doped layer interfacing the gate structure at a first point directly aligned with a vertical sidewall of the sidewall spacer contacting the gate dielectric;
• a second epitaxial-grown doped layer on the first epitaxial-grown doped layer and including a same dopant species as the first epitaxial-grown doped layer, wherein the second epitaxial-grown doped layer having a higher dopant concentration than the first epitaxial-grown doped layer, the second epitaxial-grown doped layer interfacing the gate structure along a bottom of the sidewall spacer from the first point to a second point under the bottom of the sidewall spacer away from the first point and the gate dielectric;
• and
• a third epitaxial-grown doped layer on the second epitaxial-grown doped layer and including the same dopant species as the first epitaxial-grown doped layer, wherein the third epitaxial-grown doped layer comprises a higher dopant concentration than the second epitaxial-grown doped layer, and the third epitaxial-grown doped layer interfacing the gate structure at least at the second point,
• wherein the dopant concentration is constant throughout each of the epitaxial-grown doped layers.