3D Finite Element Monte Carlo Simulations of Multigate Nanoscale Transistors

A 3D ensemble Monte Carlo device simulation tool with quantum corrections based on the tetrahedral decomposition of a simulation domain has been developed for the modeling of electron transport in nonplanar nano-MOSFETs. This 3D tool includes a presimulation drift-diffusion transport model which can also be used separately. A discretization by finite element method can accurately describe a 3D device geometry and speed up complex 3D simulations. The quantum corrections are included via a density gradient approach and the interface roughness via Ando\´s model. $I_{{\rm D}}-V_{{\rm G}}$ characteristics of a 25-nm gate length Si silicon-on-insulator (SOI) FinFET, selected as an application example, shows an excellent agreement with experimental data including the subthreshold slope. We show that the device on-current for a $\langle 110\rangle$ channel orientation could be improved by about 15% for a $\langle 100\rangle$ channel orientation. The role of quantization of energy levels affecting the distribution of electron density at sidewalls of the SOI FinFET is found to be different at low (0.05 V) and high (1.0 V) gate biases.