A Comprehensive Comparison of Different Wafer/Channel Orientations for Ultra-Scaled Nanosheet FETs

In this article, we evaluate various crystalorientation configurations for silicon ultrascaled nanosheetFETs (NSFETs) to explore the optimum combination ofwafer surface and channel orientations. The increas-ingly prominent physical phenomena, including quantumconfinement and quasi-ballistic transport, are capturedphysically by advanced simulation methodology. The car-rier density profile and transport-related parameters exhibita strong dependence on the crystallographic orientationsof the channel and the wafer directions. The quantumconfinement effects are least pronounced in the n-typeNSFETs with a (100) surface, and the p-type NSFETs witha (110) surface. The < 100 > and < 111 > channel orientationsdemonstrate the largest ballistic injection velocity for elec-trons and holes, respectively. Uniaxial stress technology,as an efficient performance booster, may further improvethe transport properties, but the enhancement may saturateat high stress level. In the ballistic limit, we predict that thehomo-oriented CMOS inverter of (110)/< 111 > configurationhas a more balanced N/P current, and the hetero-orientedCMOS inverter, comprising a 5x10 nm n-type NSFET of(100)/< 100 > and a 5x10 nm p-type NSFET of (110)/< 111 >,will yield a speed enhancement exceeding 20% whencompared with the prevailing industry standard of the(100)/< 110 > configuration