Process-variation- and random-dopants-induced threshold voltage fluctuations in nanoscale planar MOSFET and bulk FinFET devices

Impact of the intrinsic fluctuations on device characteristics, such as the threshold voltage (V_th) fluctuation is crucial in determining the behavior of nanoscale semiconductor devices. In this paper, the dependency of process-variation and random-dopant-induced V_th fluctuation on the gate oxide thickness scaling in 16 nm metal-oxide-semiconductor field effect transistors (MOSFETs) is investigated. Fluctuations of the threshold voltage for the studied planar MOSFETs with equivalent oxide thicknesses (EOT) from 1.2 nm to 0.2 nm (e.g., SiO₂ for the 1.2 and 0.8 nm EOTs, Al₂O₃ for the 0.4 nm EOT and HfO₂ for the 0.2 nm EOT) are then for the first time compared with the results of 16 nm bulk fin-typed filed effect transistors (FinFETs), which is one of the promising candidates for next generation semiconductor devices. An experimentally validated simulation is conducted to investigate the fluctuation property. Result of this study confirms the suppression of V_th fluctuations with the gate oxide thickness scaling (using high-κ dielectric). It is found that the immunity of the planar MOSFET against fluctuation suffers from nature of structural limitations. Bulk FinFETs alleviate the challenges of device's scaling and have potential in the nanoelectronics application.