Device Design Guideline of 5-nm-Node FinFETs and Nanosheet FETs for Analog/RF Applications
Jun-Sik Yoon, Rock‐Hyun Baek
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 (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> ) of FinFETs and NSFETs are comparable due to larger gate capacitances (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gg</sub> ) of NSFETs compensating DC performance improvements. Gate resistances (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ). Device design guidelines of FinFETs and NSFETs are also studied for better intrinsic gain, F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> , and F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> . Intrinsic gain is improved by better electrostatics, whereas F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> increases by greater current drivability over C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gg</sub> . For larger F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> , careful device design is required to compensate between R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> , C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gg</sub> , output resistance, and F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> . Overall, NSFETs outperform FinFETs in terms of intrinsic gain, F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</sub> , and F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> , thus NSFETs are promising for analog/RF applications.