Three-Dimensional FinFET Source/Drain and Contact Design Optimization Study

The optimization of dopant-segregated Schottky (DSS) and raised source/drain (RSD) FinFETs is investigated through a 2-D and 3-D TCAD study. ldquoSilicide gatingrdquo due to fringing fields extending from a flared silicide contact degrades DSS and RSD FinFET performances. Thus, for a multifin DSS device, the individual source/drain fins should have minimal silicide flaring and be strapped with a metal bar. For large fin pitches (FPs), this results in lower intrinsic delay and much lower delay dependence on FP than optimized RSD FinFETs, which have source/drain fins strapped using lateral epitaxial growth and accessed with vias. However, RSD FinFETs achieve lower delay for small FP and fin heights (
H

_fin
) due to low via-to-gate fringing capacitance. Thus, a new structure is proposed, called the recessed strap DSS FinFET, which combines the merits of optimized DSS and RSD FinFETs in a way that provides equivalent or improved performance over all ranges of FP and
H

_fin
.