Room Temperature Nitridation and Oxidation of Si, Ge and Mbe-grown Sige Using Low Energy Ion Beams (0.1–1 Kev).

Abstract

Direct Ion Beam Nitridation (IBN) and Oxidation (IBO) of Si, Ge, and Si_0.8Ge_0.2 were investigated at room temperature as a function of ion energy. The ion energies were selected between 100 eV and 1 keV to establish the role of energy on phase formation and film properties. Si_0.8Ge_0.2 films were grown by MBE on Si (100) and transferred in UHV to the ion beam processing chamber. The modification of composition and chemical binding was measured as a function of ion beam exposure by in situ XPS analysis. The samples were nitridized or oxidized using {ie33-1} or {ie33-2} until the N or O 1s signal reached saturation for ion doses between 5×10¹⁶ to 1×10¹⁷ ions/cm². Combined characterization by XPS, SEM, ellipsometry and cross-section TEM showed that insulating films of stoichiometric SiO₂ and Si-rich Si₃N₄ were formed during IBO and IBN of Si at all energies used. The formation of Ge dielectric thin films by IBO and IBN was found to be strongly energy dependent and insulating layers could be grown only at the lower energies (E ≤ 200 eV). In contrast to pure Ge, insulating SiGe-oxide and SiGe-nitride were successfully formed on Si_0.8Ge0.2_0.2 at all energies studied.