Metal-oxide-semiconductor characteristics of rapid thermal nitrided thin oxides

Abstract

The electrical properties of thin nitrided oxide (∼100 Å) formed by rapid thermal nitridation (RTN) in pure NH3 have been studied. It is found that the current-voltage characteristic of RTN oxides follows a Fowler–Nordheim tunneling behavior with modifications caused by electron trapping processes at the oxide surface and interface. The trapping density is dependent on the RTN conditions. At the interface, both fixed charge (Nf) and interface state (Dit) densities exhibit turnaround phenomena when the RTN process proceeds. The maximum values of Nf and Dit at the turnaround points are lower for the higher temperature RTN, suggesting a viscous flow related strain relieving mechanism associated with RTN of thin oxides. Films with superior endurance behavior (QBD=20.4 C/cm2 compared with QBD=5.1 C/cm2 of thermal oxide under 10 mA/cm2 constant current stress) have been obtained by RTN at 1000 °C, 10 s.