Analytical Model of Contact Resistance in Vertically Stacked Nanosheet FETs for Sub-3-nm Technology Node

Abstract

For the first time, a novel analytical model of contact resistance (R-contact) in vertically stacked nanosheet FETs (NSHFETs) with a silicide/Si (100) contact for a sub-3-nm node is presented. Generally, R-contact consists of the interface resistance(R-interface) and spreading resistance (R-sprea(d)). Herein, a new model of R-interface of silicide/Si (100) contact, which simultaneously considers the source/drain (S/D) doping concentration (N-si), Schottky barrier height (SBH), and SBH lowering, is demonstrated simultaneously. In addition, a new model of R(spread )that divides S/D into multiple resistance components for vertically stacked NSHFETs is suggested. In vertically stacked NSHFET with 3-nm node, for TiSi2/n-Si (100) and NiPtSi2/p-Si (100) contacts, R-spread shows more than similar to 50.0% higher values compared to R-interface. On the other hand, 3-nm node FinFET with TiSi2/n-Si (100) and NiPtSi2/p-Si (100) contacts, R-spread shows more than similar to 53.7% lower values compared to R-contact. The results show that R-spread becomes dominant in R-contact compared to R-interface when using R-s(pread) NSHFETs, in contrast to the conventional FinFETs in which R-interface is dominant in R-contact. The high R-spread of the NSHFET is mainly caused by the low nanosheet thickness and vertical pitch between the nanosheets. This study provides critical insights into the design of the source/drain of NSHFET for sub-3-nm CMOS technology.