A MODEL OF ION SYNTHESIS OF BURIED DIELECTRIC LAYERS IN SILICON

An analytical model is developed to describe heterogeneous ion synthesis of chemical phases when annealing silicon bombarded by substoichiometric ion doses. The phase grow due to segregation of impurities from the target matrix at the surface of the nuclei emerging as a result of the implantation. The growing phase centres are localized in a target layer which is thin compared to the typical width of the initial concentration profile of the implanted ions. In the region of maximal supersaturation by the impurity, phase formation at the initial stage of annealing is governed by the segregation intensity, while later it is governed by diffusion of the reagent toward the surface of the growing inclusions. The theoretical results are compared with experimental data on the synthesis of a buried Si3N4 layer with different annealing times.