Vacancy and oxygen behavior in carbon highly doped silicon

Abstract

ABSTRACTCarbon doping of silicon has gained interest since in high concentrations, carbon can reduce oreven suppress undesirable diffusion of the base dopant boron in silicon-based bipolar transistors. This behavior can only be understood in taking into account the silicon point defects i.e. vacancies and self-interstitials. In this work, we observe the oversaturation of vacancies produced by a high carbon concentration duringannealing. Experiments with a vacancy diffusing dopant, Antimony, are shown and prove this effect: in a carbon rich sample, the antimony diffusion is enhanced about 8 times compared to samples with a much lower carbonconcentration. We also investigate the carbon co-precipitation with oxygen. The carbon precipitation, asSiC, is facilitated with a high oxygen concentration. We explain this affinity by an exchange of point defects and a volume compensation. Finally, we show the precipitation of oxygen in relation to the vacancy oversaturation at 900°C.