Surface Layer Analysis of Sputter-Etched Si Using Secondary Electrons Induced by Fast Ions

Thicknesses of amorphized layers on Si(100), (110), and (111) wafers resulting from 45° sputter cleaning with Ar+in the energy range from 1 to 5 keV have been determined by analyzing secondary electrons induced by 40 MeV O5+under channeling incidence conditions. Thickness is independent of wafer orientation and increases approximately linearly with Ar+energy up to 35±5 Å for 5 keV Ar+. Since in the analysis an ambiguity associated with the surface condition of undamaged crystal is eliminated, this method is extremely useful for investigating nanometer-thick disordered surfaces.