A point defect based twodimensional model of the evolution of dislocation loops in silicon during oxidation

A point defect based mode l is developed in two dimensions for the evolution of a group of dislocation loops induced by high dose ion implantation in silicon. Assuming an asymmetr ic triangular density distribution of periodically oriented circular dislocation loops provides an efficient mode l reflecting the nonun i fo rm morpho logy of the loops as observed in transmission electron microscopy (TEM) experiments. The effective pressure f rom the ensemble of dislocation loops is numerical ly calculated on the basis of the established formulation of pressure f rom a single circular loop. The pressure field f rom the layer of dislocation loops is fundamenta l to the modeling, as it largely affects equil ibrium point defect concentra-tions 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 mode l the loop growth and shrinkage incorporating effectively the statistical processes such as loop coalescence and dissolution during oxidation. The simulation with the mode l shows reduced interstitial supersaturation during the oxida-tion 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. High dose ion implantation is an essential technique for obtaining heavily doped regions in silicon such as th