In this work we report on the structural and electrical properties of SiO2/Si3N4/HfO2 memory stacks with emphasis upon the influence of Atomic Layer Deposition chemistry used for forming the HfO2 blocking layer. Two HfO2 precursor chemistries were employed, the tetrakis- (ethylmethylamino)hafnium (TEMAH) and the bis(methylcyclopentadienyl)methoxymethylhafnium (HfD-04). Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by means of TEM and GIXRD. Comparative studies conducted with the use of platinum gated capacitors showed that the samples grown using TEMAH have an increased electron trapping ability in comparison to the HfD-04 ones. While the two structures exhibit similar Write/Erase and retention characteristics, The samples grown from TEMAH can sustain more repeated W/E cycles (> 3×105 in the 10V/-11V, 10 ms regime) compared to the samples grown from HfD-04 (< 104 W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures used with these two precursors and the nature of the interfacial layer they produce between the Si3N4 and the HfO2 layers.