US Patent 10170555 Intermetallic doping film with diffusion in source/drain

A method includes etching a substrate to form a first semiconductor strip. A first dummy gate structure is formed over a first channel region of the first semiconductor strip. First and second recesses are etched in the first semiconductor strip on either side of a first dummy gate. An intermetallic doping film is formed in the first recess and the second recess. A dopant of the intermetallic doping film is diffused into the first semiconductor strip proximate the recesses. Source/drain regions are epitaxially grown in the recesses. A device includes semiconductor strips and a plurality of gate stacks. A first epitaxial source/drain region is interposed between a first two of the plurality of gate stacks. A first dopant diffusion area surrounds the first epitaxial source/drain region and has a first concentration of a first dopant greater than a second concentration of the first dopant outside the first dopant diffusion area.