Charge trapping and dielectric wear-out properties of 8 and 30 nm SiO2 layers nitrided in the N2O gas using a Rapid Thermal System are evaluated injecting charge at either low (by avalanche technique) or high (by Fowler-Nordheim technique) electric fields. In the experimental conditions studied, the results have pointed out that, compared to a standard silicon dioxide layer, a SiO2 film nitrided in the N2O gas exhibits a reduced electron/hole trapping efficiency and, independently of the injection polarity, an improved charge-to-breakdown (Q(BD)) characteristics.