Modelling of the Native Oxide Thickness Effect on the Electrical Characteristics of Polycrystalline Emitter Transistors

In this work a transport processes model through polysilicon / oxide / single-crystal silicon structure used in bipolar technologies compatible CMOS has been studied. Several surveys have shown that the tunnel effect was the most dominating phenomenon responsible for the electrical conduction through the oxide. In order to take this effect into account as well as the thermoelectronic effect, a numerical model of calculation based on the ambipolar resolution of quantum drift-diffusion QDD equations (density gradient model) combined with Schrodinger equation has been developed. The obtained results have permitted to study the influence of oxide thickness on the evolution of the transistor electric characteristics, which lead to a technological optimization of the structure