Strained Silicon–Germanium-On-Insulator n-MOSFET With Embedded Silicon Source-and-Drain Stressors

In this letter, a strained silicon-germanium (SiGe) n-channel field-effect transistor (n-FET) featuring embedded silicon (Si) source-and-drain (S/D) stressors is demonstrated. A novel Ge-condensation technique was employed to form Si_0.75Ge_0.25-on-insulator (SGOI) substrates with excellent surface quality. Transistors with gate length L _G down to 60 nm were fabricated on the SGOI substrates. The strained n-FETs incorporated Si S/D regions, which are lattice-mismatched with respect to the Si_0.75Ge_0.25 channel, to induce uniaxial tensile strain in the Si_0.75Ge_0.25 channel for electron mobility enhancement. This leads to a 36% rise in linear drain-current and a 21% rise in saturation drive current over control SiGe channel devices at a fixed off-state current. Increasing the recess depth in S/D regions prior to the selective epitaxial growth of Si increases the channel stress, thus, a higher saturation drive-current enhancement can be achieved.