Experimental study of biaxial and uniaxial strain effects on carrier mobility in bulk and ultrathin-body SOI MOSFETs

Biaxial and uniaxial strained silicon technologies are promising for enhancement of CMOS performance. However, the advantage of uniaxial/biaxial strain over biaxial/uniaxial strain in terms of carrier mobility is not clear, since biaxial and uniaxial strain effects on carrier mobility have not till date been directly compared. Furthermore, the carrier mobility under uniaxial strain has not been fully studied in terms of strain directions. On the other hand, in spite of the importance of ultrathin-body (UTB) SOI MOSFETs to suppress the short channel effects in sub-20-nm regime, strain effects in UTB MOSFETs with SOI thickness, T_SOI, of less than 5nm have not be explored yet. In this report, biaxial and uniaxial strain effects on carrier mobility are systematically studied, for the fist time, utilizing externally applied mechanical stress. The biaxial and uniaxial strain effects in UTB MOSFETs with T_SOI of less than 5nm are also investigated, for the first time.