All-quantum simulation of an ultra-small SOI MOSFET

The all-quantum program for 3D simulation of an ultra-thin body SOI MOSFET is overviewed. It is based on Landauer-Buttiker approach to calculate current. The necessary transmission coefficients are acquired from the self-consistent solution of Schrödinger equation. The latter is stabilized with the help of expanding the wave function over the modes of transversal quantization inside the transistor channel. The program also contains a domain for onedimensional classical ballistics intended for calculation of the initial state for subsequent all-quantum simulation. This is a significant point of our approach as the straightforward procedure of the self-consistent solution of Schrödinger equation from the very beginning is diverging or, at least, extremely time-consuming. The main goal of all-quantum simulation is to clarify the impact of interference on charged impurities and quantum reflection from self-consistent potential on I-V curve reproducibility for different rand omly doped transistors in a circuit. The 10nm technology node tri-gate (wrapped channel) structure with 2nm silicon body was used in simulation. 20 discrete impurities were dispersed by the source and drain contacts to imitate the same doping. The most important feature we demonstrate is a smoothness of I-V curves in spite of beforehand apprehension. The next peculiarity we came across was that the current spanned within 10% for different discrete impurity realizations. These results manifest that the reproducibility of nanotransistors could be fairly good to make ultra-large integrated circuits still feasible. We have also made a comparison with simulations based on drift-diffusion model.