Radio-frequency variability of GAA Si NS CFETs induced by PVE and IPF simultaneously

• First-ever combined study of radio-frequency and S-parameter fluctuations under both process variation effects (PVE) and intrinsic parameter fluctuations (IPF). • For process variation effects, key geometry including NS thickness, width, and gate length, critically impact the device characteristics through their effect on surface potential and carrier transport. • Work function fluctuations from random metal grains are the dominant IPF source, strongly disturbing the channel surface potential and causing significant variability. Variability in gate-all-around (GAA) silicon nanosheet (Si NS) complementary field-effect transistors (CFETs) stems from two primary sources: process-variation effect ( PVE ) and intrinsic parameter fluctuations ( IPF ). In this work, a systematic TCAD-based variability framework is developed to quantitatively assess the impact of PVE and IPF on the analog and radio frequency (RF) performance of vertically stacked GAA Si NS CFETs. Key geometrical factors—namely NS thickness ( T NS ), width ( W NS ), and gate length ( L G )—play a pivotal role in shaping intrinsic resistance ( r o ), output resistance ( R out ), voltage gain ( A V ), cut-off frequency ( f T ), and 3-dB bandwidth ( f 3 dB ), due to their influence on surface potential profiles and carrier transport behavior. Notably, within IPF , variations are predominantly governed by random nanoscale metal grains, where work function fluctuations ( WKF ) strongly perturb the channel surface potential, thereby inducing significant variability in A V , f T , f 3 dB , other radio RF parameters. A statistically significant ensemble of calibrated device simulations is employed to decouple and quantify the individual and combined contributions of PVE and IPF . Furthermore, small-signal s-parameter analysis is performed to extract RF figures of merit under realistic loading conditions, providing practical design insights for variability-aware CFET optimizations.