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

Abstract

In the present work, the variations of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RF</i> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {gdi}}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {gsi}}$ </tex-math></inline-formula> 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.