The role of fluorine on reducing TED in boron implanted silicon

Recently, it was shown that fluorine limits the transient enhanced diffusion of the boron in the regrown silicon by a chemical species by implanting BF²⁺ and B⁺ into pre-amorphized silicon. However, it remained unclear from these studies whether the fluorine was interacting with the boron or the excess silicon interstitials from the EOR damage. In order to answer this question, a series of experiments have been performed. Amorphization of a n-type Czochralski wafer was achieved with a 70 keV Si⁺ implantation at a dose of 1×10¹⁵/cm² The Si⁺ implant produced a 1500 Å deep amorphous layer, which was then implanted with 1.12 keV 1×10¹⁵/cm² B⁺ The samples were then implanted with a dose of 2×10¹⁵ /cm²F⁺ at various energies ranging from 2 keV to 36 keV. By varying the F⁺ energy it was possible to change the position and concentration of the fluorine relative to the boron and the end-of-range interstitial source. After annealing at 750°C and 1050°C the wafers were analyzed by secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), and Hall effect. The results suggest the fluorine is reducing the TED of the boron by interacting with the boron more than the excess interstitials