Ultra-low energy ion implantation of a (001) Si surface was carried out using a mass-separated 11B+ ion beam; with ions having an energy of 30 or 200eV. The effect of implantation conditions upon the electrical properties was investigated. The sheet resistance after B implantation, at an energy of 200eV, decreased with an increase in target temperature because fewer defects, such as interstitials and vacancies, were introduced. The sheet resistance, after implantation at an energy of 30eV, saturated at a value of 6kΩ/square at an ion dose of more than 0.5 x 1016/cm2. The activation ratios of the dopant after implantation at 5.1 x 1015 and 1.03 x 1016/cm2 were 61 and 46%, respectively because, at the higher dose, B ions were introduced into the interstitial sites of Si. The implantation depth of B was 1.2nm. These results showed that ultra-shallow ion doping could be achieved with ultra-low energy ion beams at 30eV.

Ultralow-Energy Boron-Ion Implantation of Silicon. K.Yamamoto, H.Itoh: Japanese Journal of Applied Physics, 2008, 47, 23-5