RF Performance of Stacked Si Nanosheet nFETs
Journal
IEEE Transactions on Electron Devices
Journal Volume
68
Journal Issue
10
Pages
5277-5283
Date Issued
2021
Author(s)
Abstract
Stacked nanosheet nFETs considering a six-stack four-finger transistor array are studied and optimized by validated TCAD simulation. Stacked Si nanosheet (NS) nFETs have lower parasitics than nFinFETs in the same six-fin/stack four-finger transistor array layout. With the same electron mobility, back-end-of-line (BEOL), equivalent oxide thickness (EOT) of 1.4 nm, and gate length of 30 nm, the stacked Si NSs have 1.1× cut-off frequency (240 versus 215 GHz) and 1.15× maximum oscillation frequency (290 versus 251 GHz) when compared to FinFETs due to larger transconductance increase than capacitance increase and output conductance decrease. With the optimized EOT of 0.8 nm and gate length of 18 nm, the stacked Si NSs can achieve cut-off frequency of 340 GHz and maximum oscillation frequency of 370 GHz. Furthermore, considering the higher electron mobility on {100} surfaces of NSs than {110} sidewalls of FinFETs as suggested by the ID-VGS fitting, the cut-off frequency and maximum oscillation frequency of stacked Si NSs can reach 380 and 390 GHz, respectively. ? 2021 IEEE.
Subjects
5G
6G
cut-off frequency
gate-all-around
maximum oscillation frequency
mm-wave
RF
stacked nanosheets (NSs)
Electron mobility
FinFET
Nanosheets
Transconductance
Back end of lines
Equivalent oxide thickness
Gate length
Maximum oscillation frequency
Output conductance
RF performance
TCAD simulation
Transistor arrays
Silicon
Type
journal article