A Two-Dimensional Model for Interface Coupling in Triple-Gate Transistors

The influence of the fin width on substrate-to-gate coupling in long-channel silicon-on-insulator triple-gate transistors is investigated. A complementary analysis, taking into account both the "front coupling" (variation of the front-channel threshold voltage V
_T1
, as a function of the substrate bias V
_G2
) and "back coupling" (variation of the back-channel threshold voltage V
_T2
) as a function of the front-gate bias V
_G1
) characteristics has been carried out. It is shown that the back coupling, as opposed to the front coupling, is highly sensitive to the fin width in narrow-channel devices and can even be used in fin width extraction. Simple analytical 2-D models for the body potential, V
_T1
, and V
_T2
have been developed to clarify the experimental data, showing in particular the gradual control of the back interface potential by the lateral gates in narrow fins. The model stands as a 2-D generalization of the Lim and Fossum's well-known 1-D interface coupling model