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