Präzipitation von SiO₂ in Silizium nach einer Sauerstoff-Hochdosisimplantation

During ion beam synthesis of compounds in Si a specific redistribution process is responsible for the modification of the implant profile towards a uniform buried compound layer. This process is referred to as Ostwald ripening. Implantation of substoichiometric doses of reactive species leads to structures consisting of two precipitate bands. Investigations done by taking SEM-micrographs on beveled samples reveal that the structuring depends on the implantation conditions. Furthermore splitting of the precipitate band located deeper in the substrate was observed and is seen as an effect of self-organisation. The development of the structures with time depends on the strength of the ripening process taking place parallel and perpendicular to the surface of the substrate. Using methods of spatial statistics the changes in the precipitate configuration according to the different ripening directions become obivous. Unfortunately, there exists no analytical model to describe the precipitation process in systems with inhomogeneous material distribution. Therefore, all the information retained from the experiments serve as an input for simulations to be done and will help to understand the contributions of different physical mechanisms. The results obtained in the course of the present study are described in terms of the formation of a buried oxide layer as a typical example of this kind.
(Unfortunately, the thesis itself is written in german.)