Incoherent Light Annealing of Glow Discharge PF5 - Implanted Silicon: Analysis of Damage Recovery and Electrical Activation

Silicon wafers (100) orientation, were implanted with 3 × 1015 and 1 × 1016 PF5 at 30 keV by glow discharge and subsequently annealed by a commercially available lamp set-up. The annealing temperatures were in the range 620–980°C with irradiation times of 4–7 sec. Sheet resistivity and Hall measurements together with anodic oxidation stripping have been used to determine the mobility and the carrier concentration profiles; the residual damage and the presence of precipitates were investigated by Rutherford Backscattering (RBS) and Transmission Electron Microscopy (TEM). Comparison between the as-implanted dopant depth distribution and the carrier concentration profiles of the annealed samples shows the evolution of the electrically active, substitutional dopant fraction, at increasing annealing temperatures. It is found that the maximum electrical activity is obtained at 720°C; between 720°C and 820°C a process of reverse annealing takes place and the sheet resistivity increases by a factor of about 3. By annealing at temperatures higher than 820°C the substitutional dopant fraction increases again to its maximum value and it is possible to observe the presence of diffusion tails. Finally, RBS, TEM, and Deep Level Transient Spectroscopy (DLTS) were used to investigate the depth location and the evolution of the damage after annealing.