Strained ultrahigh performance fully depleted nMOSFETs with ft of 330 GHz and sub-30-nm gate lengths

Ultrahigh performance fully depleted nMOSFETs have been fabricated on ultra-thin silicon-on-insulator (UTSOI) with a body thickness of 18 nm and channel lengths down to 20 nm. Uniaxial tensile stress induced in the channel using stressed contact liners and stress memorization was found to significantly improve ac performance, resulting in cutoff frequencies f_t as high as 330 GHz. This is the highest f_T value reported on fully depleted UTSOI MOSFETs and is among the highest f_T values for any Si-based field-effect transistor. Stress memorization and stressed contact liners were found to have little impact on gate to source capacitance indicating that the enhancement in f_T results primarily from stress-induced enhancements in transconductance.