Electrical characterization of thin film, thin buried oxide SIMOX SOI substrates produced by low-energy, low-dose implantation
A range of electrical characterization techniques have been applied to thin film, thin buried oxide SIMOX SOI substrate. Some capacitance-voltage results were seen to exhibit frequency dispersion due to high concentrations of surface states but have been analysed to yield buried oxide thickness and doping levels. The ability to deplete from both interfaces of the buried oxide allowed us to determine both the density and the position of the positive charge centroid present in the oxides. The current-voltage characteristics were seen to be ohmic at low voltages (<50 V) but there is evidence that Fowler-Nordheim conduction is the dominant mechanism at higher voltages. Analysis of Fowler-Nordheim data yielded low barrier heights to electron emission in the range of 0.8 to 1.9 eV which were explained as the effect of field intensification at interfacial asperities. The I-V plots also indicated that high levels of electron trapping were occurring in the oxides and this was studied further using constant voltage stressing. The role in the trapping of excess Si and Si islands present in the implanted oxides is discussed at length.