As peaks in Si (100) films fabricated with rapid thermal epitaxy

A new method is presented for incorperating sharp arsenic n(+) peaks in silicon (100) films that are epitaxially grown in the ASMI Epsilon One reactor. For device fabrication, arsenic is an attractive dopant because it combines low thermal diffusivity with high electrical activation. However, during epitaxial growth very high As concentrations will often adsorb or segregate to the surface and high As autodoping levels may result. This As surface coverage can be completely removed at high temperatures but the corresponding high thermal dopant diffusion is often unacceptable. Optimisation of the growth conditions nevertheless has allowed the fabrication of 500 Angstrom wide As peaks with a maximum doping of 10(19) atoms/cm(3) and an autodoping level as low as 7 x 10(16) atoms/cm(3). The latter can moreover be reduced to 3 x 10(16) atoms/cm(3) by using Ge as a surfactant.