Due to the continuous scaling down of equivalent oxide thickness (EOT) requested for inter-poly dielectric (IPD) material, the Oxide-Nitride-Oxide (ONO) stack, which is currently used for this purpose, needs a valid alternative able to guarantee better charge retention properties together with higher physical thicknesses and low leakage currents. The EOT target for the 32-22 nm node is between 4 and 6 nm, while for the leakage currents a value around 1E-14 A/cm2 at low fields is requested. In principle high-k materials with a dielectric constant in the 10÷ 20 range can fulfil these requirements. We have studied nitridated Hf-silicates as possible high-k materials. In the following their chemical, morphological and electrical properties are described. In particular, the attention has been focused on how the thermal stability of these materials is improved when nitrogen is inserted in the film. The Hf-silicates have been …