Comparison of the Electrical Properties of Thermal and Ion Beam Oxides

Abstract

A comparison of the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of thermal and low temperature ion beam grown films of silicon oxide was made. The oxides were in the thickness range between 5 nm and 10 nm. The ion beam oxides were grown at room temperature. The bulk resistivities of the thermal oxides were about 10¹⁷ ohm cm and were about 5 orders of magnitude lower for the ion beam oxides. The interface charge densities at the Si-SiO₂ interface were about an order of magnitude higher in the case of the ion beam oxides. The oxide properties were also measured after current stressing at constant voltages. The thermal oxides showed an increase in the interface trap density at the Si-SiO₂ interface after stressing with a distinct trap appearing above mid-gap. The ion beam oxides showed very little increase in the interface trap density after stressing. The higher conductivity of the ion beam oxides may have lead to discharging of the interface traps generated during stressing.