Numerical Modeling of Nonuniform Si Thermal Oxidation

A general numerical model, which is suitable to describe nonuniform silicon thermal oxidation, is proposed. The oxidant diffusion through the growing oxide and the change in shape in the total system are modeled at the same time. A new formulation, based on the balance-of-force viewpoint, is accomplished for the description of the oxidation-induced deformation, taking viscoelasticity into account. Thus both compressive/tensile and shear components of stress vectors can be calculated. Utilization of distorted quadrangular grids also contributes to generalization of this model. Application of this model to LOCOS oxidation process simulations demonstrates good agreement in LOCOS shape between calculation results and experimental data and proves the feasibility of using this model in general 2-D oxidation simulations.