Properties of SiO2 films formed by oxygen implantation into silicon

Oxygen ions with energies of 5–60 keV were implanted into Si at doses of 10¹⁵–10¹⁸ ions cm^?2 to form SiO₂ layers. Annealing was carried out in nitrogen at 500–1000 °C and in hydrogen at 450 °C. By monitoring the IR transmission spectra, the refractive index, the etching behaviour and the electrical characteristics, it was established that stoichiometric SiO₂ layers can be produced with doses of 10¹⁸ ions cm^?2 on annealing at 700–1000 °C. A voltage-dependent capacitance was obtained only for samples implanted with a dose of 10¹⁸ ions cm^?2 and annealed at 1000 °C in nitrogen and at 450 °C in hydrogen. In the interface state spectrum of such samples, maxima at 0.55 eV and at 0.80 eV below the conduction band were found.