COPPER PRECIPITATION AT THE SILICON SILICON-DIOXIDE INTERFACE - ROLE OF OXYGEN

Copper contamination is often the origin of the lifetime degradation d uring processing of solar cells. Its behaviour during oxidation is inv estigated in this paper. It is shown by analytical transmission electr on microscopy that the thermal oxidation of Czochralski silicon induce s at the silicon-silicon-dioxide interface the precipitation of large copper colonies associated with oxidation-stacking-fault (OSF) Frank p artial dislocations decorated with oxygen. The precipitation process i s different in float-zone silicon where the Frank partial dislocations bounding the OSFs are themselves nucleation sites for copper precipit ates.