Abstract
Silicon oxynitride (SiON) has emerged as a better gate dielectric material to replace ultra-thin gate SiO/sub 2/ in scaled down metal-oxide-semiconductor (MOS) devices. The present study investigates the leakage current in SiON grown by a plasma-based process. Thin films of SiON (6 nm) were grown on Si substrates by nitriding rapid thermally grown SiO/sub 2/ layers in a low-energy, microwave excited nitrogen plasma and by subsequent re-oxidation; and the resulting films were characterized in Al/SiON/p-Si MOS structures under atmospheric, vacuum and low temperature conditions. The analysis of the current-voltage (I-V) characteristics obtained under atmospheric conditions shows an enhanced leakage current in the pre-Fowler-Nordheim region of 4/spl sim/8 MV/cm oxide field range. However, I-V characterization in vacuum showed the complete removal of this additional current component. This current was found to be not due to a charging/capacitive effect. It is speculated that this additional mid-ox ide-field leakage current could possibly be due to a conducting pathway given rise to by interaction of atmospheric gases/water molecules with the plasma induced defects on the oxynitride film.