The growth of the semiconductor integrated circuit industry over the last years has been fueled by continued miniaturization of transistors to ever-smaller dimensions. With the reduction of devices to 0.1 micron and less, new physical effects come into play which the standards two-dimensional (2D) simulators do not take in account. In order to de scribe the physical behavior of modern devices in a reliable way, one must improve these simulation too1s and adapt them to take into account these phenomena. As a matter of fact, the typical distance in the third distance is of the same order of magnitude as the one along the gate in a MOSFET, for instance, and lateral effect ought to be considered carefully. The general context of this thesis is inscribed here. The aim is to develop a three-dimensional (3D) simu1ator, suitable for simulating carrier transport in such small devices. During this work, we have developed two separate simulators for studying submicronic devices. Both simulators have been elaborated in a finite element environment, by coupling the Boltzmann transport equation with the Poisson equation in a 3D self-consistent way. All ofthis work was carried out on FLUX3D© (software developed at LEG for the numerical simulation of 3D electromagnetic devices by finite element method). * The first simulator is based on a determinist approach using a drift-diffusion model. * The second simulator is based on a stochastic approach consisting in particular dynamical simulation by the Monte-Carlo method. These tools represent an important contribution to device modeling, and they could even be used out of small devices context. Eventually, they can be coupled into a hybrid simulator in which Monte-Carlo and drift-diffusion models are combined. The innovating aspect of our project is the fact that many previous works using the Monte-Carlo technique are carried out in a 2D by a finite-difference method. Until now, a 3D study using a finite element method has never been employed, as far as we know, in such a simulation approach.
