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

Abstract

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 (Ft) of FinFETs and NSFETs are comparable due to larger gate capacitances (Cgg) of NSFETs compensating DC performance improvements. Gate resistances (Rg) 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 (Fmax). Device design guidelines of FinFETs and NSFETs are also studied for better intrinsic gain, Ft, and Fmax. Intrinsic gain is improved by better electrostatics, whereas Ft increases by greater current drivability over Cgg. For larger Fmax, careful device design is required to compensate between Rg, Cgg, output resistance, and Ft. Overall, NSFETs outperform FinFETs in terms of intrinsic gain, Ft, and Fmax, thus NSFETs are promising for analog/RF applications.

Keywords

• 5-nm node
• FinFETs
• NSFETs
• nanosheet
• intrinsic gain
• cutoff frequency