Triple crystal diffractometry, x-ray standing wave, and transmission electron microscopy investigation of shallow BF2 implantation in Si

Abstract

Si wafers implanted at 5, 15, and 50 keV with different BF2+ doses and next annealed at 945 °C for 45 s, were studied by means of x-ray triple crystal diffraction, x-ray standing wave, and transmission electron microscopy methods. Due to the implantation energies used, very narrow subsurface regions with a depth ranging from a few tens of nanometers to a few nanometers were damaged. By fitting the diffraction curves and using the information obtained from the photoelectrons emitted by the x-ray standing wave field, it was possible to determine the most appropriate strain and damage profiles versus depth within the disturbed region of the crystal. The above results made it possible to find: (i) the distribution of interstitial ions produced during the implant processes; (ii) the depth of amorphization of the implanted regions at the highest doses; and (iii) the appearance of extended defects (dislocation loops band) at the amorphous/crystal interface during the restoration of the lattice by the annealing process. Transmission electron microscopy investigations and electrochemical capacitance–voltage profiling measurements were made on several annealed samples and the results obtained by the x-ray diffraction and standing wave methods were confirmed.