High charge storage density integrated circuit capacitor

An integrated circuit capacitor comprising a high permittivity dielectric and a method of forming the same are disclosed herein. In one embodiment, this capacitor may be used as a DRAM storage cell. For example, a DRAM storage node electrode 22 may be formed of polysilicon. An ultrathin oxynitride passivation layer 25 (e.g. less than 1 nm) is formed on this electrode by exposure of the substrate to NO. A tantalum pentoxide layer 24 is formed over layer 25 , followed by a cell plate 26 . Passivation layer 25 allows electrode 22 to resist oxidation during deposition of layer 25 , thus preventing formation of an interfacial oxide layer. A passivation layer formed by this method may typically be deposited with shorter exposure times and lower temperatures than nitride passivation layers.