Device Design Guideline of 5-nm-Node FinFETs and Nanosheet FETs for Analog/RF Applications

Analog/RF performances of 5-nm node bulk fin-shaped field-effect transistors (FinFETs) and nanosheet FETs (NSFETs) were investigated and compared thoroughly using fully-calibrated TCAD. NSFETs have greater current drivability and gate-to-channel controllability than FinFETs under the same footprint, thus achieving larger intrinsic gain. But the cutoff frequencies (F
_t
) of FinFETs and NSFETs are comparable due to larger gate capacitances (C
_gg
) of NSFETs compensating DC performance improvements. Gate resistances (R
_g
) of NSFETs are larger because of their metal gate (MG) configuration surrounding the channels, longer MG height by the top-most NS spacing region, and the bottom transistor, thus degrading maximum oscillation frequency (F
_max
). Device design guidelines of FinFETs and NSFETs are also studied for better intrinsic gain, F
_t
, and F
_max
. Intrinsic gain is improved by better electrostatics, whereas F
_t
increases by greater current drivability over C
_gg
. For larger F
_max
, careful device design is required to compensate between R
_g
, C
_gg
, output resistance, and F
_t
. Overall, NSFETs outperform FinFETs in terms of intrinsic gain, F
_t
, and F
_max
, thus NSFETs are promising for analog/RF applications.