3D Drift-Diffusion Simulation with Quantum-Corrections of Tri-Gate MOSFETs

Accurate physical modelling of the carrier transport as well as a correct description of complex 3D geometries of advanced devices are needed in order to predict their behaviour and to optimise design. A parallel 3D drift-diffusion (D-D) simulator with quantum corrections using the density gradient approach designed to work on unstructured tetrahedral elements has been developed for the simulations of nano-MOSFETs. The 3D D-D code is applied to the simulation of a 40 nm gate length tri-gate MOSFET with a HfO₂ gate stack. The simulated I_D-V_G characteristics are in an excellent agreement with experimental data. The results from simulations with the density gradient show a quantum confinement threshold voltage shift, a deterioration of subthreshold slope and lowering of the on-current.