Rutherford backscattering analysis of silicon oxides formed by ion implanation.

This project is concerned with the Rutherford back-scattering (RBS) analysis of silicon oxide layers formed by ion implantation. The physical, optical and the electrical properties of these layers were assessed as a function of the implant dose, implant energy and the annealing treatment. To ascertain the quality and possible applications of the "implantation grown" oxides, their properties were compared with thermally grown SiO2. Layers formed by implanting oxygen with doses of 1016 to 3 X 1018 ions cm-2, at energies of 40 to 120 keV, were analysed by RBS to determine: a) the implanted oxygen profile b) the stoichiometry of the layer c) the radiation damage. The oxygen profiles agree with the theory at low doses, but at high doses a uniform layer of thickness approximately twice the projected range is formed. The area under the oxygen profile decreases for doses greater than the saturation dose, although the stoichiometry of the layer is not affected. This decrease was correlated with a reduction in the backscattered silicon signal from the implanted layer. This suggests that the oxide thickness is being reduced by sputtering. Stoichiometric SiO2 was found to be formed for a peak oxygen concentration equivalent to twice the silicon atomic density. Annealing at 1000°C had an insignificant effect on the RBS spectra of the implanted layers, however the disorder area under the interface peak was reduced by 70%. Once a uniform layer was formed this disorder area decreased with increased implanted dose. Infrared transmission, capacitance-voltage, dielectric breakdown field, current-voltage, chemical etch rate and ellipsometry measurements were used as complimentary techniques to supplement the RBS results