Patent ID: 8741725

Claim:
A method, comprising: providing a silicon layer on a buried oxide layer of a silicon-on-insulator substrate; forming a first gate electrode of a first field effect transistor on a top surface of a gate dielectric layer formed on a top surface of said silicon layer and forming a second gate of a second field effect transistor on said top surface of said gate dielectric layer; etching a trench in said silicon layer between said first and second gate electrodes, said trench extending from a top surface of said silicon layer into said silicon layer, said trench not extending to said buried oxide layer; ion implanting a dopant species into said silicon layer under a bottom of said trench to form a first doped region in said silicon layer, said first doped region doped to a first concentration; performing a first epitaxial deposition to form a first epitaxial layer doped to a second concentration in said bottom of said trench, said first epitaxial layer partially filling said trench; performing a second epitaxial deposition to form a second epitaxial layer doped to a third concentration on said first epitaxial layer in said trench; and wherein said third concentration is greater than said first and second concentrations and said first concentration is greater than said second concentration.