Electrical behavior of ultra-low energy implanted boron in silicon

In this paper an extensive characterization of the electrical activation of ultra-low energy implanted boron in silicon is reported. The Spreading Res istance Profiling technique has been used, in a suitable configuration, for measuring doped layers shallower than 100 nm, in order to extract the carr ier concentration profiles. The dependence on the implant energy, dose, and annealing temperature allowed us to gain more insight into the mechanisms responsible for the electrical activation at implant energies below 1 keV. By measuring the electrical activation as a function of time for several an nealing temperatures, the thermal activation energy for the electrical acti vation of the dopant was achieved. It slightly depends on the implant dose and it is in the range of 2-3 eV. In particular, for an implant dose of 1x1 0(14)/cm(2) it is 2.0 eV, close therefore to the 1.7 eV activation energy f ound [Napolitani , Appl. Phys. Lett. 75, 1869 (1999)] for the enhanced diff usion of ultra-low energy implanted boron. The best conditions to maximize electrical activation, while minimizing diffusion, are identified and junct ion depths of similar to 50 nm with sheet resistance below 500 Omega report ed. These data are reported and their implication for the fabrication of fu ture generation devices is discussed. (C) 2000 American Institute of Physic s. [S0021-8979(00)04215-8].