Effects of “fast” rapid thermal anneals on sub-keV boron and BF2 ion implants
The effects of “fast” ramp-rates (up to 425°C/s) and spike anneals are investigated for 0.25 keV, 0.5 keV, and 1.0 keV 11B+ and for 1.1 and 2.2 keV BF2 at a dose of 1e 15/cm2. Below an implant energy threshold where no extended defects form, fast ramp-rates become important in minimizing the thermal diffusion component and reducing the junction depth. Above this implant energy threshold, TED minimizes the advantages of these fast ramp-rates. Annealing in a low and controlled O2 ppm in N2 ambient further reduces diffusion by minimizing/eliminating oxygen related enhanced diffusion effects, while simultaneously optimizing anneal reproducibility and across-the-wafer uniformity.