Mesh-based particle simulation of sub-0.1 micron FETs

When the devices in modern integrated circuits shrink to dimensions below 100 nm the discrete nature of the charge of impurities and carriers starts to exert its influence. In this paper we describe a parallel mesh-particle approach to the simulation of sub-100 nm FETs when the impurities and the carriers are treated as individual charges. The mesh-based solution of the Poisson equation has advantages when devices with complex shapes and boundaries have to be simulated, but introduces problems related to the convergence of the parallel solvers and in resolving the short-range interparticle forces. We found that the parallel multigrid solvers have superior convergence properties for discrete charge simulations, uniformly damping the short- and long-range components of the residuals. We developed an economical approach to analytically correct the erroneous short-range component of the interparticle forces derived from the mesh-based solution. The mesh-particle approach is illustrated and verified in the simulation of a dual-gate MESFET with a channel length of 80 nm.