n-MOSFET with silicon-carbon source/drain for enhancement of carrier transport

Abstract

A novel strained-silicon (Si) n-MOSFET with 50-nm gate length is reported. The strained n-MOSFET features silicon-carbon Si1-y Cy source and drain (S/D) regions formed by a Si recess etch and a selective epitaxy of Si1-yCy in the S/D regions. The carbon mole fraction incorporated is 0.013. Lattice mismatch of ∼0.56% between Si0.987C0.013 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 ΔEc between the Si0.987C0.013source and the strained Si channel could also contribute to an increased electron injection velocity vinj from the source. Implementation of the Si0.987 C0.013 S/D regions for n-MOSFET provides significant drive current IDsat enhancement of up to 50% at a gate length of 50 nm. © 2007 IEEE.