Engineering the diffusion behavior of dopants (B, Sb) in silicon by incorporation of carbon

Abstract Carbon doping of silicon is a subject of high interest since at high concentration (> 1×10 18 cm −3 ), carbon can reduce or even suppress the undesirable diffusion of boron in silicon-based bipolar transistors. To understand this macroscopic behavior, processes of point defect interactions (i.e. between dopants, vacancies and self-interstitials) have to be analyzed. The reduction of the boron diffusion by carbon is known to be due to the creation of a self-interstitial undersaturation. In this work we discuss the influence of the oversaturation of vacancies also produced by a high carbon concentration during annealing. Experiments with a vacancy diffusing dopant, antimony, are demonstrated to prove this effect: in a carbon rich sample, the antimony diffusion is enhanced about eight times compared to samples with a much lower carbon concentration. We also investigate the carbon co-precipitation with oxygen. We explain this affinity by an exchange of point defects and a volume compensation.