Direct formation of dielectric thin films on silicon by low energy ion beam bombardment

Dielectric films with thickness of the order of 50 Å are obtained at room temperature by bombarding exposed silicon surfaces with an oxygen-containing ion beam of energy 60 eV. Silicon nitride thin films have also been formed using the same technique. The film thickness is self-limited and largely independent of ion dose. AES and XPS analysis of the produced thin films indicate that the films are not entirely stoichiometric and contain lower oxidation states of silicon. The high electrical quality of the oxide films is demonstrated by the successful fabrication of n-channel MOS transistors with gate dielectrics obtained by ion beam oxidation at room temperature.