Correlation between electron trap density and hydrogen concentration in ultrathin rapidly reoxidized nitrided oxides

Abstract
Ultrathin nitrided oxides (8 nm) were reoxidized for the first time by lamp-heated rapid thermal annealing in dry oxygen at 900–1150 °C for 15–200 s. Extensive measurements of hydrogen concentration [H] using secondary ion mass spectroscopy were performed. Electron trapping was monitored by flatband voltage shift ΔVfb under high-field stress. Both [H] and the ΔVfb decrease monotonically as reoxidation proceeds in the present experimental conditions. We have found for the first time that the ΔVfb is correlated with the [H] by a single proportional relation regardless of the fabrication condition. This fact gives evidence that the electron traps in the (reoxidized) nitrided-oxide system originate from hydrogen-containing species.