ANALYSIS AND APPLICATION OF A VISCOELASTIC MODEL FOR SILICON OXIDATION

The numerical modeling of the oxidation of silicon is analyzed from a nonlinear viscoelastic approach. Its mechanical and stress dependent parameters are determined for silicon dioxide and nitride. The study focuses on the theological behavior of the materials. The two dimensional simulations of silicon cylinders oxidation and local oxidation of silicon processing reveal that at 1000 degrees C, a nonlinear viscous modeling is equivalent to the nonlinear viscoelastic one. But, for lower temperatures, the discrepancies between these two models, observed in the stress calculation and final oxide shape, demonstrate the necessity for a complete nonlinear viscoelastic formulation. Finally, the calibrated model is used to study the growth of a recessed isolation structure. The investigations quantify the influence of geometrical parameters of the silicon groove on the shape of the final isolation oxide (e.g., parameters such as the silicon overetch under the pad oxide, the depth of silicon etching, the slope of the silicon sidewall and the silicon concave corner rounding).