Transient-enhanced diffusion of boron implanted at ultralow energies in silicon: Localization of the source

摘要

We have investigated the location of the defects causing the transient-enhanced diffusion (TED) of boron implanted at very low energies in Si. The localization was done by removing the surface layer of the silicon implanted with boron (1 and 0.5 keV, 1×10~(14)/cm~(-2)) by repeated native-oxide growth and removal. Subsequent annealing revealed the diffusion behavior. The fast and ultrafast processes of TED that where discriminated in an earlier work by Napolitani et al. Appl. Phys. Lett. 75, 1869 (1999) are found to be generated by defects located at different depths. The defects responsible for the fast tail shift are found to be located closer to the surface than the defects leading to the ultrafast tail shift. The nature of the two defect classes is discussed.