gate and storage dielectric systems and methods of their fabrication are presented . a passivated overlayer deposited between a layer of dielectric material and a gate or first storage plate maintains a high k value of the dielectric material . the high k dielectric material forms an improved interface with a substrate or second plate . this improves dielectric system reliability and uniformity and permits greater scalability , dielectric interface compatibility , structural stability , charge control , and stoichiometric reproducibility . furthermore , etch selectivity , low leakage current , uniform dielectric breakdown , and improved high temperature chemical passivity also result .