Effects of phosphorus doping on boron transient enhanced diffusion in silicon

The effects of phosphorus predoping on transient enhanced diffusion (TED) of boron, ion implanted into silicon, were studied using secondary ion mass spectroscopy (SIMS). Boron ions of 40 keV energy were implanted to a dose of 3×10¹⁴ cm^-2 into Si(100), which had been uniformly predoped with P at atomic concentrations varying between ∼3×10¹⁹ and ∼1×10²⁰ cm^-3. The effective boron diffusivity in the TED distribution and the amount of immobile boron are extracted from SIMS profiles. Our results show that both decrease with increasing P doping level, saturating beyond a P-doping level of ∼6×10¹⁹ cm^-3 after the low temperature anneal. The implications of these results for different models of modified TED behavior of boron are discussed. © 1997 American Institute of Physics.