n-MOSFET With Silicon-Carbon Source/Drain for Enhancement of Carrier Transport

A novel strained-silicon (Si) n-MOSFET with 50-nm gate length is reported. The strained n-MOSFET features silicon-carbon (Si 1-y C y ) source and drain (S/D) regions formed by a Si recess etch and a selective epitaxy of Si 1-y C y in the S/D regions. The carbon mole fraction incorporated is 0.013. Lattice mismatch of ~0.56% between Si 0.987 C 0.013 and Si results in lateral tensile strain and vertical compressive strain in the Si channel region, both contributing to substantial electron-mobility enhancement. The conduction-band offset DeltaE c between the Si 0.987 C 0.013 source and the strained Si channel could also contribute to an increased electron injection velocity nu inj from the source. Implementation of the Si 0.987 C 0.013 S/D regions for n-MOSFET provides significant drive current I Dsat enhancement of up to 50% at a gate length of 50 nm