Modelling the thermal oxidation of silicon

Two-dimensional modeling of the self-limiting oxidation in silicon and tungsten nanowires

https://doi.org/10.1016/j.taml.2016.08.002

The thermal oxidation of silicon is a key principle applied the fabrication of silicon based integrated circuits. In recent years, thermal oxidation is further used to control the size of Silicon Nanowires, SiNWs, which too have applications in microelectronics as well as photovoltaics and other emerging applications. In the study reported in the paper attached here, the self limiting behaviour of silicon oxidation and the formation of an impervious SiO2 layer at Si surfaces is studied on the basis of the Deal Grove model, a model that played a key role in the birth of the integrated circuit industry under the guidance of Bruce Deal and Andrew Grove, at Fairchild Semiconductor during the 1950s.

Fig. 1. (a) Schematic diagram of the two-dimensional cylindrical oxidation of SiNWs. (b) Profiles of the effective activation energy of O2 diffusion in the oxide.

Abstract of the report

Self-limiting oxidation of nanowires has been previously described as a reaction- or diffusion-controlled process. In this letter, the concept of finite reactive region is introduced into a diffusion-controlled model, based upon which a two-dimensional cylindrical kinetics model is developed for the oxidation of silicon nanowires and is extended for tungsten. In the model, diffusivity is affected by the expansive oxidation reaction induced stress. The dependency of the oxidation upon curvature and temperature is modeled. Good agreement between the model predictions and available experimental data is obtained. The developed model serves to quantify the oxidation in two-dimensional nanostructures and is expected to facilitate their fabrication via thermal oxidation techniques.