Equivalent Oxide Thickness of Trigate SOI MOSFETs With High- $\kappa$ Insulators

The evolution of traditional metal-oxide-semiconductor field-effect transistors (MOSFETs) from planar single-gate devices into 3-D ones with multiple gates and high-kappa insulators imposes the use of new electrical models that accurately reproduce their behavior. This paper demonstrates that the typical expression of equivalent oxide thickness (EOT) for planar devices with high- kappa gate insulators becomes useless for nonplanar ones such as triple-gate (trigate) silicon-on-insulator MOSFETs. An alternative expression of the EOT for these trigate devices has been developed through a semianalytical approach to the gate-insulator capacitance. The proposed model correctly reproduces the total electron density in a wide range of device dimensions and applied biases.