Impact of Process Fluctuations on RF Small-Signal Parameter of Gate-All-Around Nanosheet Transistor beyond 3 nm Node

In the present work, the variations of RF small-signal model parameters induced by the intrinsic process fluctuations are investigated in gate-all-around (GAA) nanosheet transistor beyond 3 nm node. With the help of nonlinear rational function fitting, the RF small-signal model parameters are first analytically extracted from the non-quasi-static (NQS) equivalent circuit. The impact of work-function variation (WFV), line edge roughness (LER), and gate edge roughness (GER) on small-signal model parameters are evaluated by 3-D TCAD simulation. Results demonstrate that the channel distribution resistance Rgdi and Rgsi are the most sensitive parameters to intrinsic process fluctuations. Furthermore, compared to LER and GER, WFV is found to have the dominated role in the variation of RF small-signal parameters, while LER and GER played a positive promotion role in aggravating the variation. The underlying physical mechanisms are discussed in detail.