A POINT-DEFECT BASED 2-DIMENSIONAL MODEL OF THE EVOLUTION OF DISLOCATION LOOPS IN SILICON DURING OXIDATION

A point defect based model is developed in two dimensions for the evolution of a group of dislocation loops induced by high dose ion implantation in silicon. Assuming an asymmetric triangular density distribution of periodically oriented circular dislocation loops provides an efficient model reflecting the nonuniform morphology of the loops as observed in transmission electron microscopy (TEM) experiments. The effective pressure from the ensemble of dislocation loops is numerically calculated on the basis of the established formulation of pressure from a single circular loop. The pressure field from the layer of dislocation loops is fundamental to the modeling, as it largely affects equilibrium point defect concentrations and boundary conditions governing emission and absorption of the point defects. Solving the pressure-dependent point defect diffusion equations in association with the simplified loop distribution and geometry makes it possible to model the loop growth and shrinkage incorporating effectively the statistical processes such as loop coalescence and dissolution during oxidation. The simulation with the model shows reduced interstitial supersaturation during the oxidation and correctly predicts the variation of the number of captured silicon atoms and the radii and densities of the dislocation loops in agreement with the TEM experiments.