DEFECT-FREE SIGE SOURCE/DRAIN FORMATION BY EPITAXY-FREE PROCESS

MOSFET transistors having localized stressors for improving carrier mobility are provided. Embodiments of the invention comprise a gate electrode formed over a substrate, a carrier channel region in the substrate under the gate electrode, and source/drain regions on either side of the carrier channel region. The source/drain regions include an embedded stressor having a lattice constant different from the substrate. In a preferred embodiment, the substrate is silicon and the embedded stressor is SiGe. Implanting a portion of the source/drain regions with Ge forms the embedded stressor. Implanting carbon into the source/drain regions and annealing the substrate after implanting the carbon suppresses dislocation formation, thereby improving device performance.